index.json

[{"authors":["admin"],"categories":null,"content":"My research group study the dynamics and impacts of the Earth’s crustal processes due to natural forces and human activities from societal to geological timescales. These phenomena include microseismicity, large earthquakes, landslides, tsunamis, faulting, uplift/subsidence in diverse environments such as geothermal fields, crustal faults, and subduction zones.\nWe address various geoscience problems using geodetic imaging (e.g., Global Navigation Satellite Systems \u0026amp; Interferometric Synthetic Aperture Radar; GNSS/InSAR), seismological observations (e.g., seismicity \u0026amp; structure), and laboratory-based computational modeling, with particular interests in multiscale inference and uncertainty quantification in geophysics. Through these multi-/inter-disciplinary efforts, we aim to better understand and assess geohazards and to improve safe, sustainable subsurface exploration.\nI always welcome motivated students and postdocs to join the group; please see Opportunities.\n","date":-62135596800,"expirydate":-62135596800,"kind":"section","lang":"en","lastmod":-62135596800,"objectID":"598b63dd58b43bce02403646f240cd3c","permalink":"https://jjle.github.io/authors/admin/","publishdate":"0001-01-01T00:00:00Z","relpermalink":"/authors/admin/","section":"author","summary":"My research group study the dynamics and impacts of the Earth’s crustal processes due to natural forces and human activities from societal to geological timescales. These phenomena include microseismicity, large earthquakes, landslides, tsunamis, faulting, uplift/subsidence in diverse environments such as geothermal fields, crustal faults, and subduction zones.\nWe address various geoscience problems using geodetic imaging (e.g., Global Navigation Satellite Systems \u0026amp; Interferometric Synthetic Aperture Radar; GNSS/InSAR), seismological observations (e.g., seismicity \u0026amp; structure), and laboratory-based computational modeling, with particular interests in multiscale inference and uncertainty quantification in geophysics.","tags":null,"title":"Junle Jiang","type":"author"},{"authors":null,"categories":null,"content":"","date":-62135596800,"expirydate":-62135596800,"kind":"section","lang":"en","lastmod":-62135596800,"objectID":"8639c2048cb98c49025b6d70450bfe45","permalink":"https://jjle.github.io/author/al-hashemi/","publishdate":"0001-01-01T00:00:00Z","relpermalink":"/author/al-hashemi/","section":"author","summary":"","tags":null,"title":"Dawoud Al Hashemi","type":"author"},{"authors":null,"categories":null,"content":"","date":-62135596800,"expirydate":-62135596800,"kind":"section","lang":"en","lastmod":-62135596800,"objectID":"dd328ea5a0142e612f00d7a7a8e0f710","permalink":"https://jjle.github.io/author/al-maamari/","publishdate":"0001-01-01T00:00:00Z","relpermalink":"/author/al-maamari/","section":"author","summary":"","tags":null,"title":"Abrar Al Maamari","type":"author"},{"authors":null,"categories":null,"content":"","date":-62135596800,"expirydate":-62135596800,"kind":"section","lang":"en","lastmod":-62135596800,"objectID":"fdeefc1c52d223b737c66a82be0964e3","permalink":"https://jjle.github.io/author/al-muzahmi/","publishdate":"0001-01-01T00:00:00Z","relpermalink":"/author/al-muzahmi/","section":"author","summary":"","tags":null,"title":"Said Al Muzahmi","type":"author"},{"authors":null,"categories":null,"content":"","date":-62135596800,"expirydate":-62135596800,"kind":"section","lang":"en","lastmod":-62135596800,"objectID":"71b414ee6a6003800f6a76176c2e26f4","permalink":"https://jjle.github.io/author/bodunde/","publishdate":"0001-01-01T00:00:00Z","relpermalink":"/author/bodunde/","section":"author","summary":"","tags":null,"title":"Segun Steven Bodunde","type":"author"},{"authors":null,"categories":null,"content":"","date":-62135596800,"expirydate":-62135596800,"kind":"section","lang":"en","lastmod":-62135596800,"objectID":"f1608f0aad14b58f1004e5b2f2809b55","permalink":"https://jjle.github.io/author/kang/","publishdate":"0001-01-01T00:00:00Z","relpermalink":"/author/kang/","section":"author","summary":"","tags":null,"title":"Zhenyu Kang","type":"author"},{"authors":null,"categories":null,"content":"","date":-62135596800,"expirydate":-62135596800,"kind":"section","lang":"en","lastmod":-62135596800,"objectID":"7e702aa083e52b899b7c9662ed9aa5ba","permalink":"https://jjle.github.io/author/li/","publishdate":"0001-01-01T00:00:00Z","relpermalink":"/author/li/","section":"author","summary":"","tags":null,"title":"Haoyu Li","type":"author"},{"authors":null,"categories":null,"content":"","date":-62135596800,"expirydate":-62135596800,"kind":"section","lang":"en","lastmod":-62135596800,"objectID":"0902dcf8a4abdcd4abb5c8a1eb29d18f","permalink":"https://jjle.github.io/author/oyugi/","publishdate":"0001-01-01T00:00:00Z","relpermalink":"/author/oyugi/","section":"author","summary":"","tags":null,"title":"Maurine Oyugi","type":"author"},{"authors":null,"categories":null,"content":"","date":-62135596800,"expirydate":-62135596800,"kind":"section","lang":"en","lastmod":-62135596800,"objectID":"afc12ec59e6af58c049743257b96a07c","permalink":"https://jjle.github.io/author/rutkauskas/","publishdate":"0001-01-01T00:00:00Z","relpermalink":"/author/rutkauskas/","section":"author","summary":"","tags":null,"title":"Calvin Rutkauskas","type":"author"},{"authors":null,"categories":null,"content":"","date":-62135596800,"expirydate":-62135596800,"kind":"section","lang":"en","lastmod":-62135596800,"objectID":"ffb741b66a6a64439eb733ef39737b66","permalink":"https://jjle.github.io/author/shodunke/","publishdate":"0001-01-01T00:00:00Z","relpermalink":"/author/shodunke/","section":"author","summary":"","tags":null,"title":"Ganiyat Shodunke","type":"author"},{"authors":null,"categories":null,"content":"","date":-62135596800,"expirydate":-62135596800,"kind":"section","lang":"en","lastmod":-62135596800,"objectID":"aad57010c0497e16c01fcdac35726907","permalink":"https://jjle.github.io/author/silva/","publishdate":"0001-01-01T00:00:00Z","relpermalink":"/author/silva/","section":"author","summary":"","tags":null,"title":"Jacqueline Silva","type":"author"},{"authors":null,"categories":null,"content":"","date":-62135596800,"expirydate":-62135596800,"kind":"section","lang":"en","lastmod":-62135596800,"objectID":"e03df347416295c3be68529e12094bcc","permalink":"https://jjle.github.io/author/thapa/","publishdate":"0001-01-01T00:00:00Z","relpermalink":"/author/thapa/","section":"author","summary":"","tags":null,"title":"Manoj Thapa","type":"author"},{"authors":null,"categories":null,"content":"","date":-62135596800,"expirydate":-62135596800,"kind":"section","lang":"en","lastmod":-62135596800,"objectID":"c2a60e27a646bad86e295cfc5c5c8547","permalink":"https://jjle.github.io/author/vera-arroyo/","publishdate":"0001-01-01T00:00:00Z","relpermalink":"/author/vera-arroyo/","section":"author","summary":"","tags":null,"title":"Alexandro Vera Arroyo","type":"author"},{"authors":null,"categories":null,"content":"","date":-62135596800,"expirydate":-62135596800,"kind":"section","lang":"en","lastmod":-62135596800,"objectID":"6cf23c484b70cb936115b00069d8acef","permalink":"https://jjle.github.io/author/viteri/","publishdate":"0001-01-01T00:00:00Z","relpermalink":"/author/viteri/","section":"author","summary":"","tags":null,"title":"Jose Viteri Lopez","type":"author"},{"authors":null,"categories":null,"content":"Graduate / Upper Undergraduate Level CoursesGPHY5020 Computational Geophysics \u0026ndash; 3 credits (2021S, 2023S, 2025S) Fundamental concepts of numerical modeling in solid Earth geophysics, including the mathematical formulation of finite difference (FDM) and finite element (FEM) methods and their applications in a range of geophysical problems such as the heat and fluid flow, deformation, and wave propagation. Students learn MATLAB/Python programming for these methods and review topics on computational methods in seismology, geomechanics, and geodynamics.\nGPHY5970 Remote Sensing \u0026amp; Space Geodesy \u0026ndash; 3 credits (2021F, 2023F) This course introduces fundamentals of remote sensing and geodetic techniques, including optical, radar, GNSS, InSAR, and related observations from current and upcoming satellite missions. Through case studies, the course covers basic geospatial analysis and parameter estimation approaches to characterize the properties and processes of land surface changes, geohazards, and resource exploration.\nGPHY4553 Introduction to Seismology \u0026ndash; 3 credits (2022S) This course presents an overview of seismology to introduce students to the fundamentals of seismic wave, quantitative data analyses, and the utilization of seismic wave for the study of earthquakes and the Earth\u0026rsquo;s interior structure. Students will gain hand-on experiences with real data analysis.\nGPHY5413 Global Geophysics \u0026ndash; 3 credits (2022F, 2023F, 2024F) Introduces students to geophysical methods, the structure and physical properties of earth\u0026rsquo;s interior, active processes on earth, and the use of geophysical methods to study structure and processes.\nGPHY3440 Mentored Research Experience \u0026ndash; 1\u0026ndash;3 credits (2021S, 2022Su, 2023F, 2024Su, 2024F) For the inquisitive student to apply the scholarly processes of the discipline to a research or creative project under the mentorship of a faculty member.\nGPHY6970 Machine Learning in Geosciences Seminar \u0026ndash; 1 credit (2021F; Co-Instructor) To introduce Geoscience students to the basic methods of machine learning in a seminar setting, with discussion and brainstorming of ideas.\nGPHY5970 Geophysical Journal Seminar \u0026ndash; 1 credit (2022S, 2022F, 2023F, 2024F) Review and discuss recent literature in the broad areas of solid Earth and exploration geophysics\n Lower Undergraduate Level CoursesGEOL1114 Physical Geology for Scientists and Engineers \u0026ndash; 3 credits (2020F, 2022S, 2024F) Plate tectonics, the makeup of continents and mountain building. Heat flow, magnetism, gravity, rock deformation, earthquakes and the earth\u0026rsquo;s interior. Surface processes including weathering, erosion, transport and deposition. Landforms, rivers, groundwater, glaciers, ocean processes, and volcanoes. Minerals and rocks. Application of geology to land-use, groundwater, mineral and fossil fuel exploration. Laboratory included.\nGPHY3013 – Data Analysis in Geoscience \u0026ndash; 3 credits (2023S) This course introduces theories and techniques in quantitative data analysis, including data visualization, probability theory, linear models, periodicity detection, filtering, correlation, interpolation, approximations, and hypothesis testing. These concepts and methods are applied to several datasets in the study of the atmosphere, streams, groundwater, seafloor, earthquakes, etc. Examples are demonstrated in MATLAB programming environment.\nGPHY2013 Frontiers of Geophysics \u0026ndash; 1 credit (2023S; Co-Instructor) Introduction to the basic theories, methods, and modern applications of geophysics. This sampler course will address topics such as, but not limited to: Electrical resistivity imaging, seismology, deep earth geophysics, remote sensing, reflection seismology, computational geophysics, and machine learning.\n","date":1710392400,"expirydate":-62135596800,"kind":"section","lang":"en","lastmod":1710392400,"objectID":"6b0512eeb5f23dcb50d5dbe994643b40","permalink":"https://jjle.github.io/teaching/","publishdate":"2024-03-14T00:00:00-05:00","relpermalink":"/teaching/","section":"teaching","summary":"Graduate / Upper Undergraduate Level CoursesGPHY5020 Computational Geophysics \u0026ndash; 3 credits (2021S, 2023S, 2025S) Fundamental concepts of numerical modeling in solid Earth geophysics, including the mathematical formulation of finite difference (FDM) and finite element (FEM) methods and their applications in a range of geophysical problems such as the heat and fluid flow, deformation, and wave propagation. Students learn MATLAB/Python programming for these methods and review topics on computational methods in seismology, geomechanics, and geodynamics.","tags":null,"title":"Courses","type":"docs"},{"authors":null,"categories":null,"content":"Data Repositories for Recent Publications Jiang, J., Erickson, B. et al. (2021). Simulation Data for \u0026ldquo;Community-Driven Code Comparisons for Three-Dimensional Dynamic Modeling of Sequences of Earthquakes and Aseismic Slip (SEAS)\u0026rdquo; [Data set]. In Journal of Geophysical Research. Zenodo. doi:10.5281/zenodo.6299674.\nMaterna, K., Barbour, A., Jiang, J., and Eneva (2022), Geodetic displacement data near North Brawley Geothermal Field, 2009-2019. Zenodo. doi:10.5281/zenodo.5949377.\nJiang, J., Bock, Y., and Klein, E. (2021). Data for \u0026ldquo;Coevolving early afterslip and aftershock signatures of a San Andreas fault rupture\u0026rdquo; [Data set]. In Science Advances. Zenodo. doi:10.5281/zenodo.4278477.\nJiang, J., and Lohman, R. (2020). Data for \u0026ldquo;Coherence-guided InSAR deformation analysis in the presence of ongoing land surface change in the Imperial Valley, California\u0026rdquo; [Data set]. In Remote Sensing of Environment. Zenodo. doi:10.5281/zenodo.3911193.\nJiang, J. and Simons, M. (2016). Data and Models for “Probabilistic imaging of tsunamigenic seafloor deformation during the 2011 Tohoku-oki Earthquake” [Data set]. In J. Geophys. Res. Solid Earth. Zenodo. doi:10.5281/zenodo.6896262.\n","date":1710392400,"expirydate":-62135596800,"kind":"section","lang":"en","lastmod":1710392400,"objectID":"77c2d2ba0979ac9954ceb502de85c1ce","permalink":"https://jjle.github.io/data/","publishdate":"2024-03-14T00:00:00-05:00","relpermalink":"/data/","section":"data","summary":"Data Repositories for Recent Publications Jiang, J., Erickson, B. et al. (2021). Simulation Data for \u0026ldquo;Community-Driven Code Comparisons for Three-Dimensional Dynamic Modeling of Sequences of Earthquakes and Aseismic Slip (SEAS)\u0026rdquo; [Data set]. In Journal of Geophysical Research. Zenodo. doi:10.5281/zenodo.6299674.\nMaterna, K., Barbour, A., Jiang, J., and Eneva (2022), Geodetic displacement data near North Brawley Geothermal Field, 2009-2019. Zenodo. doi:10.5281/zenodo.5949377.\nJiang, J., Bock, Y., and Klein, E. (2021). Data for \u0026ldquo;Coevolving early afterslip and aftershock signatures of a San Andreas fault rupture\u0026rdquo; [Data set].","tags":null,"title":"Datasets","type":"docs"},{"authors":null,"categories":null,"content":"Graduate / Upper Undergraduate Level CoursesGPHY5020 Computational Geophysics \u0026ndash; 3 credits (2021S, 2023S) Fundamental concepts of numerical modeling in solid Earth geophysics, including the mathematical formulation of finite difference (FDM) and finite element (FEM) methods and their applications in a range of geophysical problems such as the heat and fluid flow, deformation, and wave propagation. Students learn MATLAB/Python programming for these methods and review topics on computational methods in seismology, geomechanics, and geodynamics.\nGPHY5970 Remote Sensing \u0026amp; Space Geodesy \u0026ndash; 3 credits (2021F, 2023F) This course introduces fundamentals of remote sensing and geodetic techniques, including optical, radar, GNSS, InSAR, and related observations from current and upcoming satellite missions. Through case studies, the course covers basic geospatial analysis and parameter estimation approaches to characterize the properties and processes of land surface changes, geohazards, and resource exploration.\nGPHY4553 Introduction to Seismology \u0026ndash; 3 credits (2022S) This course presents an overview of seismology to introduce students to the fundamentals of seismic wave, quantitative data analyses, and the utilization of seismic wave for the study of earthquakes and the Earth\u0026rsquo;s interior structure. Students will gain hand-on experiences with real data analysis.\nGPHY5413 Global Geophysics \u0026ndash; 3 credits (2022F, 2023F, 2024F) Introduces students to geophysical methods, the structure and physical properties of earth\u0026rsquo;s interior, active processes on earth, and the use of geophysical methods to study structure and processes.\nGPHY3440 Mentored Research Experience \u0026ndash; 1\u0026ndash;3 credits (2021S, 2022Su) For the inquisitive student to apply the scholarly processes of the discipline to a research or creative project under the mentorship of a faculty member.\nGPHY6970 Machine Learning in Geosciences Seminar \u0026ndash; 1 credit (2021F; Co-Instructor) To introduce Geoscience students to the basic methods of machine learning in a seminar setting, with discussion and brainstorming of ideas.\nGPHY5970 Geophysical Journal Seminar \u0026ndash; 1 credit (2022S, 2022F, 2023F, 2024F) Review and discuss recent literature in the broad areas of solid Earth and exploration geophysics\n Lower Undergraduate Level CoursesGEOL1114 Physical Geology for Scientists and Engineers \u0026ndash; 3 credits (2020F, 2022S, 2024F) Plate tectonics, the makeup of continents and mountain building. Heat flow, magnetism, gravity, rock deformation, earthquakes and the earth\u0026rsquo;s interior. Surface processes including weathering, erosion, transport and deposition. Landforms, rivers, groundwater, glaciers, ocean processes, and volcanoes. Minerals and rocks. Application of geology to land-use, groundwater, mineral and fossil fuel exploration. Laboratory included.\nGPHY3013 – Data Analysis in Geoscience \u0026ndash; 3 credits (2023S) This course introduces theories and techniques in quantitative data analysis, including data visualization, probability theory, linear models, periodicity detection, filtering, correlation, interpolation, approximations, and hypothesis testing. These concepts and methods are applied to several datasets in the study of the atmosphere, streams, groundwater, seafloor, earthquakes, etc. Examples are demonstrated in MATLAB programming environment.\nGPHY2013 Frontiers of Geophysics \u0026ndash; 1 credit (2023S; Co-Instructor) Introduction to the basic theories, methods, and modern applications of geophysics. This sampler course will address topics such as, but not limited to: Electrical resistivity imaging, seismology, deep earth geophysics, remote sensing, reflection seismology, computational geophysics, and machine learning.\n","date":1710392400,"expirydate":-62135596800,"kind":"section","lang":"en","lastmod":1710392400,"objectID":"edf3b9c4659d6114be79d56b83e83467","permalink":"https://jjle.github.io/team/","publishdate":"2024-03-14T00:00:00-05:00","relpermalink":"/team/","section":"team","summary":"Graduate / Upper Undergraduate Level CoursesGPHY5020 Computational Geophysics \u0026ndash; 3 credits (2021S, 2023S) Fundamental concepts of numerical modeling in solid Earth geophysics, including the mathematical formulation of finite difference (FDM) and finite element (FEM) methods and their applications in a range of geophysical problems such as the heat and fluid flow, deformation, and wave propagation. Students learn MATLAB/Python programming for these methods and review topics on computational methods in seismology, geomechanics, and geodynamics.","tags":null,"title":"People","type":"docs"},{"authors":null,"categories":null,"content":"University of Oklahoma 2022\u0026ndash; Faculty Liaison, American Geophysical Union (AGU) Bridge Program\n2021\u0026ndash; Member, MCEE Diversity, Equity, and Inclusion (DEI) Council\n2021\u0026ndash; Member, OU Data Institute for Societal Challenges (DISC)\n2021\u0026ndash; Member, Honors \u0026amp; Awards Committee\n2020\u0026ndash; Member, Computer Lab Committee\n2020\u0026ndash; Member, Graduate Admission \u0026amp; Affairs Committee\n2023\u0026ndash;2024 Member, Energy Transition Geophysics Search Committee\n2020\u0026ndash;2021 Member and DEI Advocate, Environmental Geophysics Search Committee\n2020\u0026ndash;2021 Member, Petroleum Geosciences Vision Committee\nBroader Communities2023\u0026ndash; Member, SZ4D Modeling Collaboratory for Subduction (MCS) Integrative Group\n2017\u0026ndash;2023 Co-Leader (w/ B. Erickson \u0026amp; V. Lambert), Community Code Verification SEAS Group\n2022\u0026ndash;2023 Faculty Mentor, Asian Americans \u0026amp; Pacific Islanders in Geosciences (AAPIiG)\n2022\u0026ndash; Institutional Representative, Statewide California Earthquake Center (SCEC)\n2022\u0026ndash; Institutional Representative, Computational Infrastructure for Geodynamics (CIG)\n2021\u0026ndash; Institutional Representative, Western North America InSAR (WInSAR) Consortium\n2022\u0026ndash;2023 Institutional Representative, EarthScope Consortium\nReviewer for ProposalsNational Science Foundation (NSF), National Aeronautics and Space Administration (NASA), United States Geological Survey (USGS), American Chemical Society Petroleum Research Fund (ACS PRF), Dutch Research Council (NWO), German Research Foundation (DFG)\nReviewer for JournalsScience, Science Advances, Geophysical Research Letters, Journal of Geophysical Research - Solid Earth, Geophysical Journal International, Earth and Planetary Science Letters, Scientific Reports, Bulletin of the Seismological Society of America, Seismological Research Letters, Earth Planets and Space, Earth and Space Science, Pure and Applied Geophysics, Tectonophysics, Remote Sensing, Geosciences, Energies, Sensors, Earthquake Science, etc.\n","date":1710392400,"expirydate":-62135596800,"kind":"section","lang":"en","lastmod":1710392400,"objectID":"2c778b35ac809d331bccf991419ec2ed","permalink":"https://jjle.github.io/service/","publishdate":"2024-03-14T00:00:00-05:00","relpermalink":"/service/","section":"service","summary":"University of Oklahoma 2022\u0026ndash; Faculty Liaison, American Geophysical Union (AGU) Bridge Program\n2021\u0026ndash; Member, MCEE Diversity, Equity, and Inclusion (DEI) Council\n2021\u0026ndash; Member, OU Data Institute for Societal Challenges (DISC)\n2021\u0026ndash; Member, Honors \u0026amp; Awards Committee\n2020\u0026ndash; Member, Computer Lab Committee\n2020\u0026ndash; Member, Graduate Admission \u0026amp; Affairs Committee\n2023\u0026ndash;2024 Member, Energy Transition Geophysics Search Committee\n2020\u0026ndash;2021 Member and DEI Advocate, Environmental Geophysics Search Committee\n2020\u0026ndash;2021 Member, Petroleum Geosciences Vision Committee","tags":null,"title":"Professional Service","type":"docs"},{"authors":null,"categories":null,"content":"2025 Fall Admission Our group may recruit one MS/PhD graduate student in either research area below:\n  Geodetic Imaging and Modeling: Processing, modeling, and interpration of satellite-based InSAR/GNSS observations to characterize natural/anthropogenic near-surface/crustal processes and hazards. Funding Sources: NASA/NSF/OU.\n  Computational Geomechanics/Seismology: Developing and applying computational models of earthquake rupture, deformation, and fluid flow to understand natural and anthropogenic seismicity. Funding Sources: NSF/OU.\n  General Information All of our graduate students are fully supported by Graduate Teaching/Research Assistantship (GTA/GRA). Students receive stipends, tuition waiver, and healthcare benefits, with fees often covered by additional departmental scholarships.\nPlease read the general expecations below and contact me if interested. Please include a statement of your interest/motivation, CV/resume, and transcript(s) (for students) in the email.\nFor prospective MS/PhD students, you can find more details about our graduate program.\n  Undergraduate Students:\nOU students: We are always happy to discuss courses and potential research topics.\nNon-OU students: We generally host virtual/on-site undergrad summer interns.\n  MS Students: You should mention your research interests, desired knowledge and skillsets, and plans for professional work or PhD-level research in future.\n  PhD Students: You are expected to describe the broad scientific/engineering problem that you would like to pursue with my mentorship, and explain how your research interests and career plan fit in well with OU Geophysics Program and our research group.\n  Postdoctoral Researchers: Please propose or inquire about research project(s) of our mutual interests, and envision how the diverse expertise/resources of OU Geosciences program and our group can help you advance your career.\n  ","date":1710392400,"expirydate":-62135596800,"kind":"section","lang":"en","lastmod":1710392400,"objectID":"922e3daacb1f9bde274c6723f20e9679","permalink":"https://jjle.github.io/opportunities/","publishdate":"2024-03-14T00:00:00-05:00","relpermalink":"/opportunities/","section":"opportunities","summary":"2025 Fall Admission Our group may recruit one MS/PhD graduate student in either research area below:\n  Geodetic Imaging and Modeling: Processing, modeling, and interpration of satellite-based InSAR/GNSS observations to characterize natural/anthropogenic near-surface/crustal processes and hazards. Funding Sources: NASA/NSF/OU.\n  Computational Geomechanics/Seismology: Developing and applying computational models of earthquake rupture, deformation, and fluid flow to understand natural and anthropogenic seismicity. Funding Sources: NSF/OU.\n  General Information All of our graduate students are fully supported by Graduate Teaching/Research Assistantship (GTA/GRA).","tags":null,"title":"Research Opportunities","type":"docs"},{"authors":[],"categories":null,"content":"Click on the Slides button above to view the built-in slides feature.\nSlides can be added in a few ways:\n Create slides using Academic\u0026rsquo;s Slides feature and link using url_slides parameter in the front matter of the talk file Upload an existing slide deck to static/ and link using url_slides parameter in the front matter of the talk file Embed your slides (e.g. Google Slides) or presentation video on this page using shortcodes.  Further talk details can easily be added to this page using Markdown and $\\rm \\LaTeX$ math code.\n","date":1906567200,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1906567200,"objectID":"96344c08df50a1b693cc40432115cbe3","permalink":"https://jjle.github.io/talk/example/","publishdate":"2017-01-01T00:00:00-06:00","relpermalink":"/talk/example/","section":"talk","summary":"An example talk using Academic's Markdown slides feature.","tags":[],"title":"Example Talk","type":"talk"},{"authors":["Brittany A. Erickson","**Junle Jiang**","Valère Lambert","Sylvain D. Barbot","Mohamed Abdelmeguid","Martin Almquist","Jean-Paul Ampuero","Ryosuke Ando","Camilla Cattania","Alexandre Chen","Luca Dal Zilio","Shuai Deng","Eric M. Dunham","Ahmed E. Elbanna","Alice-Agnes Gabriel","Tobias W. Harvey","Yihe Huang","Yoshihiro Kaneko","Jeremy E. Kozdon","Nadia Lapusta","Duo Li","Meng Li","Chao Liang","Yajing Liu","So Ozawa","Andrea Perez-Silva","Casper Pranger","Paul Segall","Yudong Sun","Prithvi Thakur","Carsten Uphoff","Ylona van Dinther","Yuyun Yang"],"categories":null,"content":"","date":1673308800,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1673308800,"objectID":"6d292c822e763d7a9d0dd7d9823ca80a","permalink":"https://jjle.github.io/publication/erickson-2023/","publishdate":"2023-01-10T00:00:00Z","relpermalink":"/publication/erickson-2023/","section":"publication","summary":"Numerical modeling of earthquake dynamics and derived insight for seismic hazard relies on credible, reproducible model results. The sequences of earthquakes and aseismic slip (SEAS) initiative has set out to facilitate community code comparisons, and verify and advance the next generation of physics‐based earthquake models that reproduce all phases of the seismic cycle. With the goal of advancing SEAS models to robustly incorporate physical and geometrical complexities, here we present code comparison results from two new benchmark problems: BP1‐FD considers full elastodynamic effects, and BP3‐QD considers dipping fault geometries. Seven and eight modeling groups participated in BP1‐FD and BP3‐QD, respectively, allowing us to explore these physical ingredients across multiple codes and better understand associated numerical considerations. With new comparison metrics, we find that numerical resolution and computational domain size are critical parameters to obtain matching results. Codes for BP1‐FD implement different criteria for switching between quasi‐static and dynamic solvers, which require tuning to obtain matching results. In BP3‐QD, proper remote boundary conditions consistent with specified rigid body translation are required to obtain matching surface displacements. With these numerical and mathematical issues resolved, we obtain excellent quantitative agreements among codes in earthquake interevent times, event moments, and coseismic slip, with reasonable agreements made in peak slip rates and rupture arrival time. We find that including full inertial effects generates events with larger slip rates and rupture speeds compared to the quasi‐dynamic counterpart. For BP3‐QD, both dip angle and sense of motion (thrust versus normal faulting) alter ground motion on the hanging and foot walls, and influence event patterns, with some sequences exhibiting similar‐size characteristic earthquakes, and others exhibiting different‐size events. These findings underscore the importance of considering full elastodynamics and nonvertical dip angles in SEAS models, as both influence short‐ and long‐term earthquake behavior and are relevant to seismic hazard.","tags":null,"title":"Incorporating Full Elastodynamic Effects and Dipping Fault Geometries in Community Code Verification Exercises for Simulations of Earthquake Sequences and Aseismic Slip (SEAS)","type":"publication"},{"authors":["Kathryn Materna","Andrew Barbour","**Junle Jiang**","Mariana Eneva"],"categories":null,"content":"","date":1648776107,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1648776107,"objectID":"a55185a878f6d2211ff744e7b6bf6487","permalink":"https://jjle.github.io/publication/materna-2022/","publishdate":"2022-04-01T01:21:47.646765Z","relpermalink":"/publication/materna-2022/","section":"publication","summary":"The North Brawley Geothermal Field, located within the Brawley Seismic Zone of Southern California, presents a case study for understanding seismic hazards linked to fluid injection and geothermal energy extraction. An earthquake swarm near the geothermal field in 2012 included two earthquakes with magnitudes greater than 5 and was potentially preceded by a years-long aseismic slip transient. To better understand ground deformation around the geothermal field, including its evolution with time and its physical mechanisms, we analyze deformation before, during, and after the swarm using ground- and satellite-based geodetic techniques between 2009 and 2019. We integrate observations from GNSS, Sentinel-1, TerraSAR-X, UAVSAR, and leveling surveys into a single deformation history. Modeling of this new collection of observations at the North Brawley Geothermal Field provides evidence for 80% more pre-swarm aseismic slip than previously recognized from 2009-2012. During the 2012 Brawley swarm, our geodetic slip inversions closely match the results of seismic waveform inversions from the swarm events. After the 2012 swarm, surface deformation is dominated by poroelastic deformation of a shallow fluid reservoir at ","tags":null,"title":"Detection of aseismic slip and poroelastic reservoir deformation at the North Brawley Geothermal Field from 2009-2019","type":"publication"},{"authors":["**Junle Jiang**","Brittany Erickson","Valere Lambert","Jean-Paul Ampuero","Ryosuke Ando","Sylvain Barbot","Camilla Cattania","Luca Dal Zilio","Benchun Duan","Eric M. Dunham","Alice-Agnes Gabriel","Nadia Lapusta","Duo Li","Meng Li","Dunyu Liu","Yajing Liu","So Ozawa","Casper Pranger","Ylona van Dinther"],"categories":null,"content":"","date":1646184107,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1646184107,"objectID":"d0f945d8ec5383666e69d6c566248e58","permalink":"https://jjle.github.io/publication/jiang-2022/","publishdate":"2022-03-02T01:21:47.646765Z","relpermalink":"/publication/jiang-2022/","section":"publication","summary":"Dynamic modeling of sequences of earthquakes and aseismic slip (SEAS) provides a self-consistent, physics-based framework to connect, interpret, and predict diverse geophysical observations across spatial and temporal scales. Amid growing applications of SEAS models, numerical code verification is essential to ensure reliable simulation results but is often infeasible due to the lack of analytical solutions. Here, we develop two benchmarks for three-dimensional (3D) SEAS problems to compare and verify numerical codes based on boundary-element, finite-element, and finite-difference methods, in a community initiative. Our benchmarks consider a planar vertical strike-slip fault obeying a rate- and state-dependent friction law, in a 3D homogeneous, linear elastic whole-space or half-space, where spontaneous earthquakes and slow slip arise due to tectonic-like loading. We use a suite of quasi-dynamic simulations from 10 modeling groups to assess the agreement during all phases of multiple seismic cycles. We find excellent quantitative agreement among simulated outputs for sufficiently large model domains and small grid spacings. However, discrepancies in rupture fronts of the initial event are influenced by the free surface and various computational factors. The recurrence intervals and nucleation phase of later earthquakes are particularly sensitive to numerical resolution and domain-size-dependent loading. Despite such variability, key properties of individual earthquakes, including rupture style, duration, total slip, peak slip rate, and stress drop, are comparable among even marginally resolved simulations. Our benchmark efforts offer a community-based example to improve numerical simulations and reveal sensitivities of model observables, which are important for advancing SEAS models to better understand earthquake system dynamics.","tags":null,"title":"Community-Driven Code Comparisons for Three-Dimensional Dynamic Modeling of Sequences of Earthquakes and Aseismic Slip (SEAS)","type":"publication"},{"authors":null,"categories":null,"content":"In this tutorial, I\u0026rsquo;ll share my top 10 tips for getting started with Academic:\nTip 1 I started as an Assistant Professor of Geophysics in the School of Geosciences at the University of Oklahoma in Fall 2020. I am open to recruiting MS/PhD students and a postdoc to join the team. Please contact me for research opportunities if you are interested! \u0026hellip;\nTip 2 \u0026hellip;\n","date":1636783200,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1636783200,"objectID":"827ef54312d99403e9dba3ef93fb69df","permalink":"https://jjle.github.io/opportunities/career/","publishdate":"2021-11-13T00:00:00-06:00","relpermalink":"/opportunities/career/","section":"opportunities","summary":"In this tutorial, I\u0026rsquo;ll share my top 10 tips for getting started with Academic:\nTip 1 I started as an Assistant Professor of Geophysics in the School of Geosciences at the University of Oklahoma in Fall 2020. I am open to recruiting MS/PhD students and a postdoc to join the team. Please contact me for research opportunities if you are interested! \u0026hellip;\nTip 2 \u0026hellip;","tags":null,"title":"Career Page","type":"docs"},{"authors":null,"categories":null,"content":"In this tutorial, I\u0026rsquo;ll share my top 10 tips for getting started with Academic:\nTip 1 I started as an Assistant Professor of Geophysics in the School of Geosciences at the University of Oklahoma in Fall 2020. I am open to recruiting MS/PhD students and a postdoc to join the team. Please contact me for research opportunities if you are interested! \u0026hellip;\nTip 2 \u0026hellip;\n","date":1636783200,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1636783200,"objectID":"88025ddd00c766d385d736b1217bdf24","permalink":"https://jjle.github.io/teaching/career/","publishdate":"2021-11-13T00:00:00-06:00","relpermalink":"/teaching/career/","section":"teaching","summary":"In this tutorial, I\u0026rsquo;ll share my top 10 tips for getting started with Academic:\nTip 1 I started as an Assistant Professor of Geophysics in the School of Geosciences at the University of Oklahoma in Fall 2020. I am open to recruiting MS/PhD students and a postdoc to join the team. Please contact me for research opportunities if you are interested! \u0026hellip;\nTip 2 \u0026hellip;","tags":null,"title":"Career Page","type":"docs"},{"authors":null,"categories":null,"content":"In this tutorial, I\u0026rsquo;ll share my top 10 tips for getting started with Academic:\nTip 1 I started as an Assistant Professor of Geophysics in the School of Geosciences at the University of Oklahoma in Fall 2020. I am open to recruiting MS/PhD students and a postdoc to join the team. Please contact me for research opportunities if you are interested! \u0026hellip;\nTip 2 \u0026hellip;\n","date":1636783200,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1636783200,"objectID":"b0d5889ede6db329b11e7e1e6d3000d8","permalink":"https://jjle.github.io/team/career/","publishdate":"2021-11-13T00:00:00-06:00","relpermalink":"/team/career/","section":"team","summary":"In this tutorial, I\u0026rsquo;ll share my top 10 tips for getting started with Academic:\nTip 1 I started as an Assistant Professor of Geophysics in the School of Geosciences at the University of Oklahoma in Fall 2020. I am open to recruiting MS/PhD students and a postdoc to join the team. Please contact me for research opportunities if you are interested! \u0026hellip;\nTip 2 \u0026hellip;","tags":null,"title":"Career Page","type":"docs"},{"authors":null,"categories":null,"content":"In this tutorial, I\u0026rsquo;ll share my top 10 tips for getting started with Academic:\nTip 1 \u0026hellip;\n","date":1636783200,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1636783200,"objectID":"23c22979e41671c5e00b2a8627bb8899","permalink":"https://jjle.github.io/opportunities/grad/","publishdate":"2021-11-13T00:00:00-06:00","relpermalink":"/opportunities/grad/","section":"opportunities","summary":"In this tutorial, I\u0026rsquo;ll share my top 10 tips for getting started with Academic:\nTip 1 \u0026hellip;","tags":null,"title":"Grad Page","type":"docs"},{"authors":null,"categories":null,"content":"In this tutorial, I\u0026rsquo;ll share my top 10 tips for getting started with Academic:\nTip 1 \u0026hellip;\n","date":1636783200,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1636783200,"objectID":"47fd12ac85ee733f3bfd902ef34971a6","permalink":"https://jjle.github.io/teaching/grad/","publishdate":"2021-11-13T00:00:00-06:00","relpermalink":"/teaching/grad/","section":"teaching","summary":"In this tutorial, I\u0026rsquo;ll share my top 10 tips for getting started with Academic:\nTip 1 \u0026hellip;","tags":null,"title":"Grad Page","type":"docs"},{"authors":null,"categories":null,"content":"In this tutorial, I\u0026rsquo;ll share my top 10 tips for getting started with Academic:\nTip 1 \u0026hellip;\n","date":1636783200,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1636783200,"objectID":"85ddbf1c1ffbd05fbd52d1c8a81ba865","permalink":"https://jjle.github.io/team/grad/","publishdate":"2021-11-13T00:00:00-06:00","relpermalink":"/team/grad/","section":"team","summary":"In this tutorial, I\u0026rsquo;ll share my top 10 tips for getting started with Academic:\nTip 1 \u0026hellip;","tags":null,"title":"Grad Page","type":"docs"},{"authors":null,"categories":null,"content":"In this tutorial, I\u0026rsquo;ll share my top 10 tips for getting started with Academic:\nTip 1 \u0026hellip;\n","date":1636783200,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1636783200,"objectID":"4e83eb64a577a1838e3a9a70ca905693","permalink":"https://jjle.github.io/opportunities/mentor/","publishdate":"2021-11-13T00:00:00-06:00","relpermalink":"/opportunities/mentor/","section":"opportunities","summary":"In this tutorial, I\u0026rsquo;ll share my top 10 tips for getting started with Academic:\nTip 1 \u0026hellip;","tags":null,"title":"Mentoring Philosophy","type":"docs"},{"authors":null,"categories":null,"content":"In this tutorial, I\u0026rsquo;ll share my top 10 tips for getting started with Academic:\nTip 1 \u0026hellip;\n","date":1636783200,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1636783200,"objectID":"13f14e294af0ac1a9b16688e640e2502","permalink":"https://jjle.github.io/teaching/mentor/","publishdate":"2021-11-13T00:00:00-06:00","relpermalink":"/teaching/mentor/","section":"teaching","summary":"In this tutorial, I\u0026rsquo;ll share my top 10 tips for getting started with Academic:\nTip 1 \u0026hellip;","tags":null,"title":"Mentoring Philosophy","type":"docs"},{"authors":null,"categories":null,"content":"In this tutorial, I\u0026rsquo;ll share my top 10 tips for getting started with Academic:\nTip 1 \u0026hellip;\n","date":1636783200,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1636783200,"objectID":"8e2de92841a937c063ad3c85a4cdcbda","permalink":"https://jjle.github.io/team/mentor/","publishdate":"2021-11-13T00:00:00-06:00","relpermalink":"/team/mentor/","section":"team","summary":"In this tutorial, I\u0026rsquo;ll share my top 10 tips for getting started with Academic:\nTip 1 \u0026hellip;","tags":null,"title":"Mentoring Philosophy","type":"docs"},{"authors":["**Junle Jiang**","Yehuda Bock","Emilie Klein"],"categories":null,"content":"","date":1617235200,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1617235200,"objectID":"31581916be743e7c3d94e7db244a7692","permalink":"https://jjle.github.io/publication/jiang-2021/","publishdate":"2021-04-09T18:25:12.6959Z","relpermalink":"/publication/jiang-2021/","section":"publication","summary":"Large earthquakes often lead to transient deformation and enhanced seismic activity, with their fastest evolution occurring at the early, ephemeral post-rupture period. Here, we investigate this elusive phase using geophysical observations from the 2004 moment magnitude 6.0 Parkfield, California, earthquake. We image continuously evolving afterslip, along with aftershocks, on the San Andreas fault over a minutes-to-days postseismic time span. Our results reveal a multistage scenario, including immediate onset of afterslip following tens-of-seconds-long coseismic shaking, short-lived slip reversals within minutes, expanding afterslip within hours, and slip migration between subparallel fault strands within days. The early afterslip and associated stress changes appear synchronized with local aftershock rates, with increasing afterslip often preceding larger aftershocks, suggesting the control of afterslip on fine-scale aftershock behavior. We interpret complex shallow processes as dynamic signatures of a three-dimensional fault-zone structure. These findings highlight important roles of aseismic source processes and structural factors in seismicity evolution, offering potential prospects for improving aftershock forecasts.","tags":null,"title":"Coevolving Early Afterslip and Aftershock Signatures of a San Andreas Fault Rupture","type":"publication"},{"authors":["**Junle Jiang**","Rowena B. Lohman"],"categories":null,"content":"","date":1604188800,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1604188800,"objectID":"0602fe8dde41c45a5ded5fd9a2d96130","permalink":"https://jjle.github.io/publication/jiang-2020/","publishdate":"2020-11-01T00:00:00Z","relpermalink":"/publication/jiang-2020/","section":"publication","summary":"While the quality and availability of Interferometric Synthetic Aperture Radar (InSAR) data has dramatically improved in recent years, InSAR analysis and interpretation remain challenging in actively deforming regions with extensive agricultural activities, where vegetation changes and soil moisture variability can degrade data quality or introduce confounding signals. Here we use Sentinel-1 satellite imagery for the Imperial Valley, California, over the period of 2015– 2019 to explore how factors specific to land surface changes may impact InSAR time series and to resolve time-varying deformation due to tectonic processes and geothermal energy production. We examine the temporal variability of data quality, via interferometric phase coherence, at high spatial resolution, taking into account the observation that some agricultural fields lie fallow for long time intervals punctuated by periods of cultivation. This strategy allows us to better distinguish signals and noise associated with agricultural activities, shoreline changes, or surface soil conditions. A series of masking, interpolation, and filtering steps facilitate phase unwrapping, and the unwrapped, unfiltered product is then recovered, reducing artifacts from spatial filtering. We adopt model-based tropospheric corrections to improve time series results, particularly in regions with high topographic relief, along with the use of distributed reference points to render a more uniform error structure. We validate InSAR observations with continuous GPS where available and find that the estimates of average line-of-sight (LOS) velocity over the valley from InSAR and GPS agree to ~ 3 mm/yr in areas with good data coverage. Discrepancies between the two estimates often exist in areas with lower InSAR data quality; in better-constrained areas, they appear to reveal signals attributable to surficial processes occurring in the uppermost soil layers. We observe a diverse suite of natural signals over multiple spatial scales, including steady interseismic deformation, seasonal lake-level-modulated signals at the southeastern Salton Sea shore, and transient slow slip on the Superstition Hills fault. In addition, we observe complex deformation at four geothermal fields within the valley. Extensive subsidence at the Salton Sea geothermal field suggests spatial overlap of anthropogenic and tectonic deformation, interspersed with potential surficial signals. Geothermal sites at East Mesa, North Brawley, and Heber exhibit smaller-amplitude, more localized deformation, often with nonlinear temporal trends. Our analysis demonstrates the need to assess whether InSAR signals result from surficial changes or deeper sources, and produces robust ground deformation data in support of efforts to study subsurface processes, manage geothermal operations, and improve hazard assessments.","tags":["Anthropogenic activity","Fault creep","Geodetic imaging","Geothermal operation","GPS","Ground deformation","InSAR","Lake level change","Land use","Regional tectonics","Soil moisture","Tropospheric noise","Uncertainty quantification"],"title":"Coherence-Guided InSAR Deformation Analysis in the Presence of Ongoing Land Surface Changes in the Imperial Valley, California","type":"publication"},{"authors":["Brittany A. Erickson","**Junle Jiang**","Michael Barall","Nadia Lapusta","Eric M. Dunham","Ruth Harris","Lauren S. Abrahams","Kali L. Allison","Jean-Paul Ampuero","Sylvain Barbot","Camilla Cattania","Ahmed Elbanna","Yuri Fialko","Benjamin Idini","Jeremy E. Kozdon","Valère Lambert","Yajing Liu","Yingdi Luo","Xiao Ma","Maricela Best McKay","Paul Segall","Pengcheng Shi","Martijn van den Ende","Meng Wei"],"categories":null,"content":"","date":1583020800,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1583020800,"objectID":"1bd706c39363c914fc3f615dc03bc165","permalink":"https://jjle.github.io/publication/erickson-2020/","publishdate":"2020-03-01T00:00:00Z","relpermalink":"/publication/erickson-2020/","section":"publication","summary":"Numerical simulations of sequences of earthquakes and aseismic slip (SEAS) have made great progress over past decades to address important questions in earthquake physics. However, significant challenges in SEAS modeling remain in resolving multiscale interactions between earthquake nucleation, dynamic rupture, and aseismic slip, and understanding physical factors controlling observables such as seismicity and ground deformation. The increasing complexity of SEAS modeling calls for extensive efforts to verify codes and advance these simulations with rigor, reproducibility, and broadened impact. In 2018, we initiated a community code-verification exercise for SEAS simulations, supported by the Southern California Earthquake Center. Here, we report the findings from our first two benchmark problems (BP1 and BP2), designed to verify different computational methods in solving a mathematically well-defined, basic faulting problem. We consider a 2D antiplane problem, with a 1D planar vertical strike-slip fault obeying rate-and-state friction, embedded in a 2D homogeneous, linear elastic half-space. Sequences of quasi-dynamic earthquakes with periodic occurrences (BP1) or bimodal sizes (BP2) and their interactions with aseismic slip are simulated. The comparison of results from 11 groups using different numerical methods show excellent agreements in long-term and coseismic fault behavior. In BP1, we found that truncated domain boundaries influence interseismic stressing, earthquake recurrence, and coseismic rupture, and that model agreement is only achieved with sufficiently large domain sizes. In BP2, we found that complexity of fault behavior depends on how well physical length scales related to spontaneous nucleation and rupture propagation are resolved. Poor numerical resolution can result in artificial complexity, impacting simulation results that are of potential interest for characterizing seismic hazard such as earthquake size distributions, moment release, and recurrence times. These results inform the development of more advanced SEAS models, contributing to our further understanding of earthquake system dynamics.","tags":null,"title":"The Community Code Verification Exercise for Simulating Sequences of Earthquakes and Aseismic Slip (SEAS)","type":"publication"},{"authors":null,"categories":null,"content":"We study surface changes, ground deformation, and seismicity in various settings. We primarily use remote-sensing techniques, e.g., multi-temporal Interferometric Synthetic Aperture Radar (InSAR) and GPS, and other auxiliary datasets to characterize robust ground deformation history in regions under the influences of tectonics (e.g., fault-zone deformation), surficial processes (e.g., soil moisture), and/or anthropogenic activities (e.g., agriculture and energy production).\nOur focus is on the connections between surface observations and subsurface processes, including the existence or absence of seismicity. The overarching goal is to improve our understanding of earthquake triggering and the state and heterogeneity of stress in the shallow crust. Our research areas include Central and Southern California, Oklahoma, and Southern Kansas.\n","date":1577858403,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1577858403,"objectID":"0ddeea3ae7806574202e66070c1c510c","permalink":"https://jjle.github.io/project/deformation/","publishdate":"2020-01-01T00:00:03-06:00","relpermalink":"/project/deformation/","section":"project","summary":"Characterizing near-surface and subsurface processes in tectonic and industrial settings","tags":["anthropogenic","geodesy","deformation","seismicity","surface change"],"title":"Land Surface Changes, Ground Deformation, and Seismicity","type":"project"},{"authors":null,"categories":null,"content":"My interests under this broad topic include dynamic earthquake ruptures, interactions between seismic and aseismic processes, observations from geodesy, seismology, and geology, laboratory-based constitutive laws.\n","date":1577858402,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1577858402,"objectID":"d327f6102228963fcce065ae8756c018","permalink":"https://jjle.github.io/project/earthquake/","publishdate":"2020-01-01T00:00:02-06:00","relpermalink":"/project/earthquake/","section":"project","summary":"Deciphering interactions of transient and long-term processes and their physical mechanisms","tags":["faults","seismicity","geodesy","deformation","rock mechanics","megathrust"],"title":"Fault Zone Mechanics and Earthquake Physics","type":"project"},{"authors":null,"categories":null,"content":"Extracting important and relevant physics from data and developing models with predictive power will be a significant task in the future of Earth sciences. Many of my observation-oriented projects share the theme of utilizing a Bayesian probabilistic inference framework (analytical and numerical sampling approaches) with an emphasis on uncertainty quantification of observations and physical modeling, along with its impact on our predictions.\nThe second, complementary part of my research involves developing cross-scale computational models with detailed physics and predictive powers to understand earthquakes, tsunamis, or slow slip. We are also interested in the verification and validation of these complex models. I take a special interest in the synergy of developing inverse and forward modeling in geophysical problems to eventually improve observation-drive, physics-based inference about the future behavior of our Earth.\n","date":1577858400,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1577858400,"objectID":"e7ac455074e502ee7d97387b36f39ae3","permalink":"https://jjle.github.io/project/computation/","publishdate":"2020-01-01T00:00:00-06:00","relpermalink":"/project/computation/","section":"project","summary":"Developing novel quantitative methods for geophysical inference and predictive modeling","tags":["computation","seismicity","fault","seismology"],"title":"Computational Geophysics","type":"project"},{"authors":["Ekaterina Tymofyeyeva","Yuri Fialko","**Junle Jiang**","Xiaohua Xu","David Sandwell","Roger Bilham","Thomas K. Rockwell","Chelsea Blanton","Faith Burkett","Allen Gontz","Shahram Moafipoor"],"categories":null,"content":"","date":1564617600,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1564617600,"objectID":"9bac6f4c3fcafca8a33608bc6eb03d64","permalink":"https://jjle.github.io/publication/tymofyeyeva-2019/","publishdate":"2019-08-01T00:00:00Z","relpermalink":"/publication/tymofyeyeva-2019/","section":"publication","summary":"Abstract Observations of shallow fault creep reveal increasingly complex time-dependent slip histories that include quasi-steady creep and triggered as well as spontaneous accelerated slip events. Here we report a recent slow slip event on the southern San Andreas fault (SSAF) triggered by the 2017 Mw8.2 Chiapas (Mexico) earthquake that occurred 3000 km away. Geodetic and geologic observations indicate that surface slip on the order of 10 mm occurred on a 40-km-long section of the SSAF between the Mecca Hills and Bombay Beach, starting minutes after the Chiapas earthquake and continuing for more than a year. Both the magnitude and the depth extent of creep vary along strike. We derive a high-resolution map of surface displacements by combining Sentinel-1 Interferometric Synthetic Aperture Radar (InSAR) acquisitions from different lines of sight. InSAR-derived displacements are in good agreement with the creepmeter data and field mapping of surface offsets. Inversions of surface displacement data using dislocation models indicate that the highest amplitudes of surface slip are associated with shallow ($","tags":null,"title":"Slow Slip Event on the Southern San Andreas Fault Triggered by the 2017 Mw8.2 Chiapas (Mexico) Earthquake","type":"publication"},{"authors":["Junle Jiang"],"categories":[],"content":"from IPython.core.display import Image Image(\u0026#39;https://www.python.org/static/community_logos/python-logo-master-v3-TM-flattened.png\u0026#39;) print(\u0026#34;Welcome to Academic!\u0026#34;) Welcome to Academic!  Install Python and Jupyter Install Anaconda which includes Python 3 and Jupyter notebook.\nOtherwise, for advanced users, install Jupyter notebook with pip3 install jupyter.\nCreate a new blog post as usual Run the following commands in your Terminal, substituting \u0026lt;MY_WEBSITE_FOLDER\u0026gt; and my-post with the file path to your Academic website folder and a name for your blog post (without spaces), respectively:\ncd \u0026lt;MY_WEBSITE_FOLDER\u0026gt; hugo new --kind post post/my-post cd \u0026lt;MY_WEBSITE_FOLDER\u0026gt;/content/post/my-post/ Create or upload a Jupyter notebook Run the following command to start Jupyter within your new blog post folder. Then create a new Jupyter notebook (New \u0026gt; Python Notebook) or upload a notebook.\njupyter notebook Convert notebook to Markdown jupyter nbconvert Untitled.ipynb --to markdown --NbConvertApp.output_files_dir=. # Copy the contents of Untitled.md and append it to index.md: cat Untitled.md | tee -a index.md # Remove the temporary file: rm Untitled.md Edit your post metadata Open index.md in your text editor and edit the title etc. in the front matter according to your preference.\nTo set a featured image, place an image named featured into your post\u0026rsquo;s folder.\nFor other tips, such as using math, see the guide on writing content with Academic.\n","date":1549324800,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1549324800,"objectID":"6e929dc84ed3ef80467b02e64cd2ed64","permalink":"https://jjle.github.io/post/jupyter/","publishdate":"2019-02-05T00:00:00Z","relpermalink":"/post/jupyter/","section":"post","summary":"Learn how to blog in Academic using Jupyter notebooks","tags":[],"title":"Display Jupyter Notebooks with Academic","type":"post"},{"authors":["Baptiste Gombert","Zacharie Duputel","Romain Jolivet","Mark Simons","**Junle Jiang**","Cunren Liang","Eric J Fielding","Luis Rivera"],"categories":null,"content":"","date":1514764800,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1514764800,"objectID":"d2e9faf81ed50a0ac82fa0948f78ecd1","permalink":"https://jjle.github.io/publication/gombert-2018/","publishdate":"2018-01-01T00:00:00Z","relpermalink":"/publication/gombert-2018/","section":"publication","summary":"The 2016 Pedernales earthquake (MW=7.8) ruptured a portion of the Colombia–Ecuador subduction interface where several large historical earthquakes have been documented since the great 1906 earthquake (M=8.6). Considering all significant ruptures that occurred in the region, it has been suggested that the cumulative moment generated co-seismically along this part of the subduction over the last century exceeds the moment deficit accumulated inter-seismically since 1906. Such an excess challenges simple models with earthquakes resetting the elastic strain accumulated inter-seismically in locked asperities. These inferences are however associated with large uncertainties that are generally unknown. The impact of spatial smoothing constraints on co-seismic and inter-seismic models also prevents any robust assessment of the strain budget. We propose a Bayesian kinematic slip model of the 2016 Pedernales earthquake using the most comprehensive dataset to date including InSAR and GPS offsets, tsunami waveforms, and kinematic records from high-rate GPS and strong-motions. In addition, we use inter-seismic geodetic velocities to produce a probabilistic inter-seismic coupling model of the subduction interface. Our stochastic co-seismic and inter-seismic solutions include the ensemble of all plausible models consistent with our prior information and that fit the observations within uncertainties. The analysis of these model ensembles indicates that an excess of co-seismic moment during the 1906–2016 period is likely in Central Ecuador only if we assume that 1942 and 2016 earthquakes are colocated. If this assumption is relaxed, we show that this conclusion no longer holds given uncertainties in co- and inter-seismic processes. The comparison of 1942 and 2016 teleseismic records reveals large uncertainties in the location of the 1942 event, hampering our ability to draw strong conclusions on the unbalanced moment budget in the region. Our results also show a heterogeneous coupling of the subduction interface that coincides with two slip asperities in our co-seismic model for the 2016 Pedernales earthquake and with the location of historical ruptures in 1958, 1979 and 1998. The spatial variability in coupling and complexity in earthquake history suggest strong heterogeneities in frictional properties of the subduction megathrust.","tags":["bayesian inversion","Ecuador–Colombia subduction zone","geodetic coupling model","kinematic source model","strain budget"],"title":"Strain Budget of the Ecuador–Colombia Subduction Zone: A Stochastic View","type":"publication"},{"authors":["Xiaohua Xu","Lauren A Ward","**Junle Jiang**","Bridget Smith-Konter","Ekaterina Tymofyeyeva","Eric O Lindsey","Arthur G Sylvester","David T Sandwell"],"categories":null,"content":"","date":1514764800,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1514764800,"objectID":"f3e2cd6e7542d6bdc53defef399689d9","permalink":"https://jjle.github.io/publication/xu-2018/","publishdate":"2018-01-01T00:00:00Z","relpermalink":"/publication/xu-2018/","section":"publication","summary":"Abstract A major challenge for understanding the physics of shallow fault creep has been to observe and model the long-term effect of stress changes on creep rate. Here we investigate the surface creep along the southern San Andreas fault (SSAF) using data from interferometric synthetic aperture radar spanning over 25 years (ERS 1992?1999, ENVISAT 2003?2010, and Sentinel-1 2014?present). The main result of this analysis is that the average surface creep rate increased after the Landers event and then decreased by a factor of 2?7 over the past few decades. We consider quasi-static and dynamic Coulomb stress changes on the SSAF due to these three major events. From our analysis, the elevated creep rates after the Landers can only be explained by static stress changes, indicating that even in the presence of dynamically triggered creep, static stress changes may have a long-lasting effect on SSAF creep rates.","tags":["coulomb stress change","shallow fault creep","temporal change","time scale‐dependent complexity"],"title":"Surface Creep Rate of the Southern San Andreas Fault Modulated by Stress Perturbations from Nearby Large Events","type":"publication"},{"authors":["**Junle Jiang**","Nadia Lapusta"],"categories":null,"content":"","date":1483228800,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1483228800,"objectID":"4f943f9d0bbaee7e64e52c5e9c6deeab","permalink":"https://jjle.github.io/publication/jiang-2017/","publishdate":"2017-01-01T00:00:00Z","relpermalink":"/publication/jiang-2017/","section":"publication","summary":"Thickness of the seismogenic zone is commonly determined based on the depth of microseismicity or the fault locking depth inferred from geodetic observations. The relation between the two estimates and their connection to the depth limit of large earthquakes remain elusive. Here we explore the seismic and geodetic observables in models of faults governed by laboratory-based friction laws that combine quasi-static rate-and-state friction and enhanced dynamic weakening. Our models suggest that the transition between the locked and fully creeping regions can occur over a broad depth range. The effective locking depth, D elock , associated with concentrated loading and promoting microseismicity, is located at the top of this transition zone; the geodetic locking depth, D glock , inverted from surface geodetic observations, corresponds to the depth of fault creeping with approximately half of the long-term rate. Following large earthquakes, D elock either stays unchanged or becomes shallower due to creep penetrating into the shallower locked areas, whereas D glock deepens as the slip deficit region expands, compensating for the afterslip. As the result, the two locking depths diverge in the late interseismic period, consistent with available seismic and geodetic observations from several major fault segments in Southern California. We find that D glock provides a bound on the depth limit of large earthquakes in our models. However, the assumed layered distribution of fault friction and simple depth estimates are insufficient to characterize more heterogeneous faults, e.g., ones with significant along-strike variations. Improved observations and models are needed to illuminate physical properties and seismic potential of fault zones.","tags":["dynamic weakening","fault mechanics","geodetic locking","large earthquakes","microseismicity","rate-and-state friction"],"title":"Connecting Depth Limits of Interseismic Locking, Microseismicity, and Large Earthquakes in Models of Long-Term Fault Slip","type":"publication"},{"authors":["Han Yue","Mark Simons","Zacharie Duputel","**Junle Jiang**","Eric Fielding","Cunren Liang","Susan Owen","Angelyn Moore","Bryan Riel","Jean Paul Ampuero","Sergey V Samsonov"],"categories":null,"content":"","date":1483228800,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1483228800,"objectID":"eb145d5309ae05177257d92a407d324b","permalink":"https://jjle.github.io/publication/yue-2017/","publishdate":"2017-01-01T00:00:00Z","relpermalink":"/publication/yue-2017/","section":"publication","summary":"On April 25th 2015, the Mw 7.8 Gorkha (Nepal) earthquake ruptured a portion of the Main Himalayan Thrust underlying Kathmandu and surrounding regions. We develop kinematic slip models of the Gorkha earthquake using both a regularized multi-time-window (MTW) approach and an unsmoothed Bayesian formulation, constrained by static and high rate GPS observations, synthetic aperture radar (SAR) offset images, interferometric SAR (InSAR), and teleseismic body wave records. These models indicate that Kathmandu is located near the updip limit of fault slip and approximately 20km south of the centroid of fault slip. Fault slip propagated unilaterally along-strike in an ESE direction for approximately 140km with a 60km cross-strike extent. The deeper portions of the fault are characterized by a larger ratio of high frequency (0.03–0.2Hz) to low frequency slip than the shallower portions. From both the MTW and Bayesian results, we can resolve depth variations in slip characteristics, with higher slip roughness, higher rupture velocity, longer rise time and higher complexity of subfault source time functions in the deeper extents of the rupture. The depth varying nature of rupture characteristics suggests that the up-dip portions are characterized by relatively continuous rupture, while the down-dip portions may be better characterized by a cascaded rupture. The rupture behavior and the tectonic setting indicate that the earthquake may have ruptured both fully seismically locked and a deeper transitional portions of the collision interface, analogous to what has been seen in major subduction zone earthquakes.","tags":["Bayesian inversion","Gorkha earthquake","Joint inversion","Kinematic rupture process inversion"],"title":"Depth Varying Rupture Properties during the 2015 Mw 7.8 Gorkha (Nepal) Earthquake","type":"publication"},{"authors":["Sylvain Michel","Jean-Philippe Avouac","Nadia Lapusta","**Junle Jiang**"],"categories":null,"content":"","date":1483228800,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1483228800,"objectID":"372aa26d9afa294f1abc4b27829bba0f","permalink":"https://jjle.github.io/publication/michel-2017/","publishdate":"2017-01-01T00:00:00Z","relpermalink":"/publication/michel-2017/","section":"publication","summary":"Megathrust earthquakes tend to be confined to fault areas locked in the interseismic period and often rupture them only partially. For example, during the 2015 M7.8 Gorkha earthquake, Nepal, a slip pulse propagating along strike unzipped the bottom edge of the locked portion of the Main Himalayan Thrust (MHT). The lower edge of the rupture produced dominant high-frequency ($$1 Hz) radiation of seismic waves. We show that similar partial ruptures occur spontaneously in a simple dynamic model of earthquake sequences. The fault is governed by standard laboratory-based rate-and-state friction with the aging law and contains one homogenous velocity-weakening (VW) region embedded in a velocity-strengthening (VS) area. Our simulations incorporate inertial wave-mediated effects during seismic ruptures (they are thus fully dynamic) and account for all phases of the seismic cycle in a self-consistent way. Earthquakes nucleate at the edge of the VW area and partial ruptures tend to stay confined within this zone of higher prestress, producing pulse-like ruptures that propagate along strike. The amplitude of the high-frequency sources is enhanced in the zone of higher, heterogeneous stress at the edge of the VW area.","tags":["Gorkha earthquake","High Frequency Radiation","Main Himalayan Thrust","Megathrusts","Partial Ruptures","Pulse"],"title":"Pulse-like Partial Ruptures and High-Frequency Radiation at Creeping-Locked Transition during Megathrust Earthquakes","type":"publication"},{"authors":["Wenyuan Fan","Dan Bassett","**Junle Jiang**","Peter M Shearer","Chen Ji"],"categories":null,"content":"","date":1483228800,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1483228800,"objectID":"21f8b8d9b149bbc967e57d173c1a11dc","permalink":"https://jjle.github.io/publication/fan-2017/","publishdate":"2017-01-01T00:00:00Z","relpermalink":"/publication/fan-2017/","section":"publication","summary":"The 2006 Mw 7.8 Java earthquake was a tsunami earthquake, exhibiting frequency-dependent seismic radiation along strike. High-frequency global back-projection results suggest two distinct rupture stages. The first stage lasted $∼$65s with a rupture speed of $∼$1.2km/s, while the second stage lasted from $∼$65 to 150s with a rupture speed of $∼$2.7km/s. High-frequency radiators resolved with back-projection during the second stage spatially correlate with splay fault traces mapped from residual free-air gravity anomalies. These splay faults also colocate with a major tsunami source associated with the earthquake inferred from tsunami first-crest back-propagation simulation. These correlations suggest that the splay faults may have been reactivated during the Java earthquake, as has been proposed for other tsunamigenic earthquakes, such as the 1944 Mw 8.1 Tonankai earthquake in the Nankai Trough.","tags":["Back-projection","Earthquake","Java","Seismology","Splay faults","Tsunami"],"title":"Rupture Evolution of the 2006 Java Tsunami Earthquake and the Possible Role of Splay Faults","type":"publication"},{"authors":["**Junle Jiang**","Nadia Lapusta"],"categories":null,"content":"","date":1475280000,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1475280000,"objectID":"1ed35c5afa24cd6fbcf172fc70f75d4e","permalink":"https://jjle.github.io/publication/jiang-2016/","publishdate":"2016-10-01T00:00:00Z","relpermalink":"/publication/jiang-2016/","section":"publication","summary":"Why many major strike-slip faults known to have had large earthquakes are silent in the interseismic period is a long-standing enigma. One would expect small earthquakes to occur at least at the bottom of the seismogenic zone, where deeper aseismic deformation concentrates loading. We suggest that the absence of such concentrated microseismicity indicates deep rupture past the seismogenic zone in previous large earthquakes. We support this conclusion with numerical simulations of fault behavior and observations of recent major events. Our modeling implies that the 1857 Fort Tejon earthquake on the San Andreas Fault in Southern California penetrated below the seismogenic zone by at least 3 to 5 kilometers. Our findings suggest that such deeper ruptures may occur on other major fault segments, potentially increasing the associated seismic hazard.","tags":null,"title":"Deeper Penetration of Large Earthquakes on Seismically Quiescent Faults","type":"publication"},{"authors":null,"categories":null,"content":"I am interested in understanding earthquake and tsunami hazards in major subduction zones around the world, e.g., East Japan, Nankai Trough, Chile, Peru, Cascadia, Alaska, Sumatra, New Zealand, etc. One of the significant questions I hope to address is the tsunamigenic processes of shallow megathrust and outer wedge of the forearc, and the associated tsunami propagation and coastal inundation processes. I am also interested in the rheology and heterogeneity of deeper megathrusts and their implications for seismic behavior and coastal shaking.\n","date":1461733200,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1461733200,"objectID":"f0a59ed7f569c6fa920e2822888adb73","permalink":"https://jjle.github.io/backup-material/subduction/","publishdate":"2016-04-27T00:00:00-05:00","relpermalink":"/backup-material/subduction/","section":"backup-material","summary":"Understanding seismic and tsunami hazards in subduction zones","tags":["subduction-zones"],"title":"Subduction Zone and Tsunami Processes","type":"backup-material"},{"authors":["Junle Jiang"],"categories":null,"content":"Academic makes it easy to create a beautiful website for free using Markdown. Customize anything on your site with widgets, themes, and language packs.\nFollow our easy step by step guide to learn how to build your own free website with Academic. Check out the personal demo or the business demo of what you\u0026rsquo;ll get in less than 10 minutes.\n View the documentation Ask a question Request a feature or report a bug Updating? View the Update Guide and Release Notes Support development of Academic:  Donate a coffee Become a backer on Patreon Decorate your laptop or journal with an Academic sticker Wear the T-shirt    \nKey features:\n Easily manage various content including homepage, blog posts, publications, talks, and projects Extensible via color themes and widgets/plugins Write in Markdown for easy formatting and code highlighting, with LaTeX for mathematical expressions Social/academic network linking, Google Analytics, and Disqus comments Responsive and mobile friendly Simple and refreshing one page design Multilingual and easy to customize  Color Themes Academic is available in different color themes and font themes.\n         Ecosystem  Academic Admin: An admin tool to import publications from BibTeX or import assets for an offline site Academic Scripts: Scripts to help migrate content to new versions of Academic  Install You can choose from one of the following four methods to install:\n one-click install using your web browser (recommended) install on your computer using Git with the Command Prompt/Terminal app install on your computer by downloading the ZIP files install on your computer with RStudio  Quick install using your web browser  Install Academic with Netlify  Netlify will provide you with a customizable URL to access your new site   On GitHub, go to your newly created academic-kickstart repository and edit config.toml to personalize your site. Shortly after saving the file, your site will automatically update Read the Quick Start Guide to learn how to add Markdown content. For inspiration, refer to the Markdown content which powers the Demo  Install with Git Prerequisites:\n Download and install Git Download and install Hugo    Fork the Academic Kickstart repository and clone your fork with Git:\n git clone https://github.com/sourcethemes/academic-kickstart.git My_Website  Note that if you forked Academic Kickstart, the above command should be edited to clone your fork, i.e. replace sourcethemes with your GitHub username.\n  Initialize the theme:\n cd My_Website git submodule update --init --recursive    Install with ZIP  Download and extract Academic Kickstart Download and extract the Academic theme to the themes/academic/ folder from the above step  Install with RStudio View the guide to installing Academic with RStudio\nQuick start   If you installed on your computer, view your new website by running the following command:\n hugo server  Now visit localhost:1313 and your new Academic powered website will appear. Otherwise, if using Netlify, they will provide you with your URL.\n  Read the Quick Start Guide to learn how to add Markdown content, customize your site, and deploy it. For inspiration, refer to the Markdown content which powers the Demo\n  Build your site by running the hugo command. Then host it for free using Github Pages or Netlify (refer to the first installation method). Alternatively, copy the generated public/ directory (by FTP, Rsync, etc.) to your production web server (such as a university\u0026rsquo;s hosting service).\n  Updating Feel free to star the project on Github to help keep track of updates and check out the release notes prior to updating your site.\nBefore updating the framework, it is recommended to make a backup of your entire website directory (or at least your themes/academic directory) and record your current version number.\nBy default, Academic is installed as a Git submodule which can be updated by running the following command:\ngit submodule update --remote --merge Check out the update guide for full instructions and alternative methods.\nFeedback \u0026amp; Contributing Please use the issue tracker to let me know about any bugs or feature requests, or alternatively make a pull request.\nFor support, head over to the Hugo discussion forum.\nLicense Copyright 2016-present George Cushen.\nReleased under the MIT license.\n","date":1461128400,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1515823200,"objectID":"279b9966ca9cf3121ce924dca452bb1c","permalink":"https://jjle.github.io/post/getting-started/","publishdate":"2016-04-20T00:00:00-05:00","relpermalink":"/post/getting-started/","section":"post","summary":"Create a beautifully simple website or blog in under 10 minutes.","tags":["Academic"],"title":"Academic: the website designer for Hugo","type":"post"},{"authors":["Quentin Bletery","Anthony Sladen","**Junle Jiang**","Mark Simons"],"categories":null,"content":"","date":1451606400,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1451606400,"objectID":"8f9c765153719384719552599f29e70d","permalink":"https://jjle.github.io/publication/bletery-2016/","publishdate":"2016-01-01T00:00:00Z","relpermalink":"/publication/bletery-2016/","section":"publication","summary":"The 2004 Mw 9.1?9.3 Sumatra-Andaman earthquake is one of the largest earthquakes of the modern instrumental era. Despite considerable efforts to analyze this event, the different available observations have proven difficult to reconcile in a single finite-fault slip model. In particular, the critical near-field geodetic records contain variable and significant postseismic signal (between 2 weeks' and 2 months' worth), while the satellite altimetry records of the associated tsunami are affected by various sources of uncertainties (e.g., source rupture velocity and mesoscale oceanic currents). In this study, we investigate the quasi-static slip distribution of the Sumatra-Andaman earthquake by carefully accounting for the different sources of uncertainties in the joint inversion of available geodetic and tsunami data. To this end, we use nondiagonal covariance matrices reflecting both observational and modeling uncertainties in a fully Bayesian inversion framework. Modeling errors can be particularly large for great earthquakes. Here we consider a layered spherical Earth for the static displacement field, nonhydrostatic equations for the tsunami, and a 3-D megathrust interface geometry to alleviate some of the potential epistemic uncertainties. The Bayesian framework then enables us to derive families of possible models compatible with the unevenly distributed and sometimes ambiguous measurements. We infer two regions of high fault slip at 3°N?4°N and 7°N?8°N with amplitudes that likely reach values as large as 40 m and possibly larger. These values are a factor of 2 larger than typically found in previous studies?potentially an outcome of commonly assumed forms of regularization. Finally, we find that fault rupture very likely involved shallow slip. Within the resolution provided by the existing data, we cannot rule out the possibility that fault rupture reached the trench.","tags":["Bayesian","earthquake","inverse theory","slip model","Sumatra-Andaman","tsunami"],"title":"A Bayesian Source Model for the 2004 Great Sumatra-Andaman Earthquake","type":"publication"},{"authors":["**Junle Jiang**"],"categories":null,"content":"","date":1451606400,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1451606400,"objectID":"e623db3d3f6d15ab7d6a0295a0c25ee0","permalink":"https://jjle.github.io/publication/jiang-2016-a/","publishdate":"2016-01-01T00:00:00Z","relpermalink":"/publication/jiang-2016-a/","section":"publication","summary":"","tags":null,"title":"Probabilistic Imaging and Dynamic Modeling of Earthquake Source Processes","type":"publication"},{"authors":["**Junle Jiang**","Mark Simons"],"categories":null,"content":"","date":1451606400,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1451606400,"objectID":"2b26670ffad2b83ce1586fbac16b8c83","permalink":"https://jjle.github.io/publication/jiang-2016-b/","publishdate":"2016-01-01T00:00:00Z","relpermalink":"/publication/jiang-2016-b/","section":"publication","summary":"Diverse observations from the 2011 Mw 9.0 Tohoku-oki earthquake pointed to large coseismic fault slip proximal to the Japan Trench. This seismic failure prompted a reevaluation of the conventional view that the outer fore-arc is generally aseismic. However, the nature of near-trench fault slip during this event remains debated, without consensus on whether slip peaked at the trench or at greater depths. Here we develop a probabilistic approach to image the spatiotemporal evolution of coseismic seafloor displacement from near-field tsunami observations. In a Bayesian framework, we sample ensembles of nonlinear models parameterized to focus on near-trench features, incorporating the uncertainty in modeling dispersive tsunami waves in addition to nominal observational errors. Our models indicate that seafloor in the region of the earthquake was broadly uplifted and tilted seaward approaching the deep-ocean trench. Over length scales of 40 km, seafloor uplift peaks at 5 $pm$ 0.6 m near the inner-outer fore-arc transition and decreases to 2 m at the trench axis over a distance of 50 km, corresponding to a seafloor tilt of 0.06 $pm$ 0.02 m/km. Over length scales of 20 km, peak uplift reaches 7 $pm$ 2 m at the similar location, but uplift at the trench is less constrained. Elastic modeling that reproduces the observed tilt requires a coseismic slip deficit at the trench. Such a deficit is effectively consistent with a metastable frictional model for the shallowest megathrust. While large shallow earthquakes in the region cannot be completely ruled out, aseismic deformation is the most likely mode for satisfying the long-term slip budget.","tags":["Bayesian inversion","seafloor deformation","subduction zone megathrust","Tohoku-oki earthquake","tsunami","uncertainty characterization"],"title":"Probabilistic Imaging of Tsunamigenic Seafloor Deformation during the 2011 Tohoku-Oki Earthquake","type":"publication"},{"authors":["**Junle Jiang**","Yuri Fialko"],"categories":null,"content":"","date":1451606400,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1451606400,"objectID":"fefec0073038153444182266c7e52a0c","permalink":"https://jjle.github.io/publication/jiang-2016-c/","publishdate":"2016-01-01T00:00:00Z","relpermalink":"/publication/jiang-2016-c/","section":"publication","summary":"Observations from the Anza section of the San Jacinto Fault in Southern California reveal that microseismicity extends to depths of 15?18?km, while the geodetically determined locking depth is less than 10?km. This contrasts with observations from other major faults in the region and also with predictions of fault models assuming a simple layered distribution of frictional properties with depth. We suggest that an anomalously shallow geodetic fault locking may result from a transition zone at the bottom of seismogenic layer with spatially heterogeneous frictional properties. Numerical models of faults that incorporate stochastic heterogeneity at transitional depths successfully reproduce the observed depth relation between seismicity and geodetic locking, as well as complex spatiotemporal patterns of microseismicity with relatively scarce repeating earthquakes. Our models predict propagation of large earthquakes to the bottom of the transition zone, and ubiquitous aseismic transients below the locked zone, potentially observable using high-precision geodetic techniques.","tags":["aseismic transients","earthquake rupture","fault mechanics","geodetic locking","rate-and-state friction","seismicity"],"title":"Reconciling Seismicity and Geodetic Locking Depths on the Anza Section of the San Jacinto Fault","type":"publication"},{"authors":null,"categories":null,"content":"I am particularly interested in exploring the wide spetrum of dynamic Earth processes by intergrating seismological and geodetic observations. These efforts include imaging space-time patterns of fault slip during and after earthquakes (strong motion, GPS, tide gauges, and tsunami waveforms), inferring frequency-dependent signals during the potential activation of splay faulting (seismic records and tsunami waveforms), and, more recently, imaging the continuous transition from earthquake arrest to postseismic fault slip (strong motion records, high-rate GPS, and daily GPS).\nRecent Conference Presentation\nJ Jiang, Y Bock, and E Klein, Imaging slip evolution on the San Andreas fault due to the 2004 Parkfield earthquake, AGU Fall Meeting Abstracts, 2018\n","date":1430110800,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1430110800,"objectID":"2a4f3740ef1e633a4ba6b94c07905d00","permalink":"https://jjle.github.io/backup-material/data/","publishdate":"2015-04-27T00:00:00-05:00","relpermalink":"/backup-material/data/","section":"backup-material","summary":"Utilizing diverse datasets to probe multiscale dynamic processes","tags":["seismology","geodesy","data-inference"],"title":"Integration of Seismic-Geodetic Observations","type":"backup-material"},{"authors":["Zacharie Duputel","**Junle Jiang**","Romain Jolivet","Mark Simons","Luis Rivera","Jean-Paul Ampuero","Bryan Riel","Susan E Owen","Angelyn W Moore","Sergey V Samsonov","Francisco Ortega Culaciati","Susan E Minson"],"categories":null,"content":"","date":1420070400,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1420070400,"objectID":"fdc61f96e6b8df0b3466a9983c59f3c6","permalink":"https://jjle.github.io/publication/duputel-2015/","publishdate":"2015-01-01T00:00:00Z","relpermalink":"/publication/duputel-2015/","section":"publication","summary":"The subduction zone in northern Chile is a well-identified seismic gap that last ruptured in 1877. On 1 April 2014, this region was struck by a large earthquake following a two week long series of foreshocks. This study combines a wide range of observations, including geodetic, tsunami, and seismic data, to produce a reliable kinematic slip model of the Mw=8.1 main shock and a static slip model of the Mw=7.7 aftershock. We use a novel Bayesian modeling approach that accounts for uncertainty in the Green's functions, both static and dynamic, while avoiding nonphysical regularization. The results reveal a sharp slip zone, more compact than previously thought, located downdip of the foreshock sequence and updip of high-frequency sources inferred by back-projection analysis. Both the main shock and the Mw=7.7 aftershock did not rupture to the trench and left most of the seismic gap unbroken, leaving the possibility of a future large earthquake in the region.","tags":null,"title":"The Iquique Earthquake Sequence of April 2014: Bayesian Modeling Accounting for Prediction Uncertainty","type":"publication"},{"authors":["Sarah E Minson","Mark Simons","James L Beck","Francisco Ortega","**Junle Jiang**","Susan E Owen","Angelyn W Moore","Asaf Inbal","Anthony Sladen"],"categories":null,"content":"","date":1406869200,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1406869200,"objectID":"a0e2ef98a420ad07a35aa62362cb1503","permalink":"https://jjle.github.io/publication/minson-2014/","publishdate":"2014-08-01T00:00:00-05:00","relpermalink":"/publication/minson-2014/","section":"publication","summary":"We present a fully Bayesian inversion of kinematic rupture parameters for the 2011 Mw9 Tohoku-oki, Japan earthquake. Albeit computationally expensive, this approach to kinematic source modelling has the advantage of producing an ensemble of slip models that are consistent with physical a priori constraints, realistic data uncertainties, and realistic but simplistic uncertainties in the physics of the kinematic forward model, all without being biased by non-physical regularization constraints. Combining 1 Hz kinematic GPS, static GPS offsets, seafloor geodesy and near-field and far-field tsunami data into a massively parallel Monte Carlo simulation, we construct an ensemble of samples of the posterior probability density function describing the evolution of fault rupture. We find that most of the slip is concentrated in a depth range of 10--20 km from the trench, and that slip decreases towards the trench with significant displacements at the toe of wedge occurring in just a small region. Estimates of static stress drop and rupture velocity are ambiguous. Due to the spatial compactness of the fault rupture, the duration of the entire rupture was less than approximately 150 s.","tags":["Computational seismology; Earthquake source observations; Inverse theory; Probability distributions"],"title":"Bayesian inversion for finite fault earthquake source models -- II: the 2011 great Tohoku-oki, Japan earthquake","type":"publication"},{"authors":null,"categories":null,"content":"Numerical simulations of Sequences of Earthquakes and Aseismic Slip (SEAS) have made great progress over the past decades to address important questions in earthquake physics and fault mechanics. Significant challenges in SEAS modeling remain in resolving multiscale interactions between aseismic fault slip, earthquake nucleation, and dynamic rupture; and understanding physical factors controlling observables such as seismicity and ground deformation. The increasing capability and complexity of SEAS modeling calls for extensive efforts to verify and advance these simulations with rigor, reproducibility, and broadened impact. Over the past year, we have initiated a community code-verification exercise for SEAS simulations, supported by SCEC (the Southern California Earthquake Center). Through this exercise, we aim to develop best practices, and code-verification and simulation tools for SEAS modeling that would benefit a larger community.\nWe have completed our first two benchmarks, designed to test the capabilities of different computational methods in correctly solving a mathematically well-defined, basic problem in crustal faulting. These benchmarks are based on a 2D antiplane problem, with a 1D planar vertical strike-slip fault obeying rate-and-state friction, embedded in a 2D homogeneous, linear elastic half-space. The fault has a shallow seismogenic region with velocity-weakening friction and a deeper velocity-strengthening region, below which a relative plate motion rate is imposed. A periodic sequence of spontaneous, quasi-dynamic earthquakes and slow slip are simulated in the model. We have established an online platform for modelers to upload and compare simulation results. The comparison of ~20 models from 11 groups using different numerical methods (FDM/FEM/BEM) show excellent general agreements. We found that domain truncation and boundary conditions strongly influence interseismic fault stressing, earthquake recurrence, and coseismic rupture speed, and that agreement between models is only achieved with sufficiently large domain sizes. Building on this initial success, we are working toward more complex scenarios involving variable event sizes, a dipping fault, and a 3D problem in our upcoming benchmarks.\nOnline benchmark platform\nhttp://scecdata.usc.edu/cvws/seas/\nOur SCEC Workshop in April, 2018\nhttps://www.scec.org/workshops/2018/cvws-seas\nOur SCEC Workshop in November, 2018\nhttps://www.scec.org/workshops/2018/seas\nOur presentations at 2018 SCEC/AGU\nJiang, J., \u0026amp; Erickson, B. A. (2018, 08). Advancing Simulations of Sequences of Earthquakes and Aseismic Slip [SEAS]. Oral Presentation at 2018 SCEC Annual Meeting. SCEC Contribution 8325\\\nErickson, B. A., Jiang, J., Barall, M., Lapusta, N., Dunham, E. M., Harris, R. A., Abrahams, L., Allison, K. L., Ampuero, J., Barbot, S. D., Cattania, C., Elbanna, A. E., Fialko, Y., Idini Zabala, B., Kozdon, J. E., Lambert, V. R., Liu, Y., Luo, Y., Ma, X., Segall, P., Shi, P., \u0026amp; Wei, M. (2018, 07). The Community Code Verification Exercise for Simulating Sequences of Earthquakes and Aseismic Slip (SEAS): Initial Benchmarks and Future Directions. Poster Presentation at 2018 SCEC Annual Meeting. SCEC Contribution 8214\\\nErickson, B. A., Jiang, J., Barall, M., Lapusta, N., Dunham, E. M., Harris, R. A., Abrahams, L., Allison, K. L., Ampuero, J., Barbot, S. D., Cattania, C., Elbanna, A. E., Fialko, Y., Idini Zabala, B., Kozdon, J. E., Lambert, V. R., Liu, Y., Luo, Y., Ma, X., Segall, P., Shi, P., \u0026amp; Wei, M. (2018, 07). The Community Code Verification Exercise for Simulating Sequences of Earthquakes and Aseismic Slip (SEAS): Initial Benchmarks and Future Directions. AGU Fall Meeting Abstracts, 2018\\\n","date":1398574800,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1398574800,"objectID":"5ce5636a630e51a74fded2becf2c197a","permalink":"https://jjle.github.io/backup-material/seas/","publishdate":"2014-04-27T00:00:00-05:00","relpermalink":"/backup-material/seas/","section":"backup-material","summary":"Advancing geophysical modeling with rigor, reproducibility, and broadened impact","tags":["SEAS","numerical-simulation","community-work"],"title":"Community Modeling Initiative - SEAS","type":"backup-material"},{"authors":["Quentin Bletery","Anthony Sladen","Bertrand Delouis","Martin Vallée","Jean Mathieu Nocquet","Lucie Rolland","**Junle Jiang**"],"categories":null,"content":"","date":1388534400,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1388534400,"objectID":"1607ce56e16507d19475d6caf6bfb8f0","permalink":"https://jjle.github.io/publication/bletery-2014/","publishdate":"2020-11-26T03:12:45.072516Z","relpermalink":"/publication/bletery-2014/","section":"publication","summary":"The 11 March 2011 Mw9.0 Tohoku-Oki earthquake was recorded by an exceptionally large amount of diverse data offering a unique opportunity to investigate the details of this major megathrust rupture. Many studies have taken advantage of the very dense Japanese onland strong motion, broadband, and continuous GPS networks in this sense. But resolution tests and the variability in the proposed solutions have highlighted the difficulty to uniquely resolve the slip distribution from these networks, relatively distant from the source region, and with limited azimuthal coverage. In this context, we present a finite fault slip joint inversion including an extended amount of complementary data (teleseismic, strong motion, high-rate GPS, static GPS, seafloor geodesy, and tsunami records) in an attempt to reconcile them into a single better resolved model. The inversion reveals a patchy slip distribution with large slip (up to 64 m) mostly located updip of the hypocenter and near the trench. We observe that most slip is imaged in a region where almost no earthquake was recorded before the main shock and around which intense interplate seismicity is observed afterward. At a smaller scale, the largest slip pattern is imaged just updip of an important normal fault coseismically activated. This normal fault has been shown to be the mark of very low dynamic friction allowing extremely large slip to propagate up to the free surface. The spatial relationship between this normal fault and our slip distribution strengthens its key role in the rupture process of the Tohoku-Oki earthquake.","tags":null,"title":"A Detailed Source Model for the Mw9.0 Tohoku-Oki Earthquake Reconciling Geodesy, Seismology, and Tsunami Records","type":"publication"},{"authors":["Shengji Wei","Robert Graves","Don Helmberger","Jean-Philippe Avouac","**Junle Jiang**"],"categories":null,"content":"","date":1325376000,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1325376000,"objectID":"767db1f567b186d50522ead05c317a21","permalink":"https://jjle.github.io/publication/wei-2012/","publishdate":"2012-01-01T00:00:00Z","relpermalink":"/publication/wei-2012/","section":"publication","summary":"Modeling strong ground motions from great subduction zone earthquakes is one of the great challenges of computational seismology. To separate the rupture characteristics from complexities caused by 3D sub-surface geology requires an extraordinary data set such as provided by the recent Mw9.0 Tohoku-Oki earthquake. Here we combine deterministic inversion and dynamically guided forward simulation methods to model over one thousand high-rate GPS and strong motion observations from 0 to 0.25Hz across the entire Honshu Island. Our results display distinct styles of rupture with a deeper generic interplate event ($∼$Mw8.5) transitioning to a shallow tsunamigenic earthquake ($∼$Mw9.0) at about 25km depth in a process driven by a strong dynamic weakening mechanism, possibly thermal pressurization. This source model predicts many important features of the broad set of seismic, geodetic and seafloor observations providing a major advance in our understanding of such great natural hazards.","tags":["Finite fault","High-rate GPS","Strong motion","Tohoku-Oki earthquake","Tsunami"],"title":"Sources of Shaking and Flooding during the Tohoku-Oki Earthquake: A Mixture of Rupture Styles","type":"publication"},{"authors":["Mark Simons","Sarah E Minson","Anthony Sladen","Francisco Ortega","**Junle Jiang**","Susan E Owen","Lingsen Meng","Jean-Paul Ampuero","Shengji Wei","Risheng Chu","Donald V Helmberger","Hiroo Kanamori","Eric Hetland","Angelyn W Moore","Frank H Webb"],"categories":null,"content":"","date":1293840000,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1293840000,"objectID":"412aac9c607a2e77e3448e05e53d5b2a","permalink":"https://jjle.github.io/publication/simons-2011/","publishdate":"2011-01-01T00:00:00Z","relpermalink":"/publication/simons-2011/","section":"publication","summary":"Geophysical observations from the 2011 moment magnitude (M(w)) 9.0 Tohoku-Oki, Japan earthquake allow exploration of a rare large event along a subduction megathrust. Models for this event indicate that the distribution of coseismic fault slip exceeded 50 meters in places. Sources of high-frequency seismic waves delineate the edges of the deepest portions of coseismic slip and do not simply correlate with the locations of peak slip. Relative to the M(w) 8.8 2010 Maule, Chile earthquake, the Tohoku-Oki earthquake was deficient in high-frequency seismic radiation–a difference that we attribute to its relatively shallow depth. Estimates of total fault slip and surface secular strain accumulation on millennial time scales suggest the need to consider the potential for a future large earthquake just south of this event.","tags":null,"title":"The 2011 Magnitude 9.0 Tohoku-Oki Earthquake: Mosaicking the Megathrust from Seconds to Centuries","type":"publication"},{"authors":null,"categories":null,"content":"Welcome to Slides Academic\n Features  Efficiently write slides in Markdown 3-in-1: Create, Present, and Publish your slides Supports speaker notes Mobile friendly slides   Controls  Next: Right Arrow or Space Previous: Left Arrow Start: Home Finish: End Overview: Esc Speaker notes: S Fullscreen: F Zoom: Alt + Click PDF Export: E   Code Highlighting Inline code: variable\nCode block:\nporridge = \u0026#34;blueberry\u0026#34; if porridge == \u0026#34;blueberry\u0026#34;: print(\u0026#34;Eating...\u0026#34;)  Math In-line math: $x + y = z$\nBlock math:\n$$ f\\left( x \\right) = ;\\frac{{2\\left( {x + 4} \\right)\\left( {x - 4} \\right)}}{{\\left( {x + 4} \\right)\\left( {x + 1} \\right)}} $$\n Fragments Make content appear incrementally\n{{% fragment %}} One {{% /fragment %}} {{% fragment %}} **Two** {{% /fragment %}} {{% fragment %}} Three {{% /fragment %}} Press Space to play!\nOne Two Three  A fragment can accept two optional parameters:\n class: use a custom style (requires definition in custom CSS) weight: sets the order in which a fragment appears   Speaker Notes Add speaker notes to your presentation\n{{% speaker_note %}} - Only the speaker can read these notes - Press `S` key to view {{% /speaker_note %}} Press the S key to view the speaker notes!\n Only the speaker can read these notes Press S key to view    Themes  black: Black background, white text, blue links (default) white: White background, black text, blue links league: Gray background, white text, blue links beige: Beige background, dark text, brown links sky: Blue background, thin dark text, blue links    night: Black background, thick white text, orange links serif: Cappuccino background, gray text, brown links simple: White background, black text, blue links solarized: Cream-colored background, dark green text, blue links   Custom Slide Customize the slide style and background\n{{\u0026lt; slide background-image=\u0026#34;/img/boards.jpg\u0026#34; \u0026gt;}} {{\u0026lt; slide background-color=\u0026#34;#0000FF\u0026#34; \u0026gt;}} {{\u0026lt; slide class=\u0026#34;my-style\u0026#34; \u0026gt;}}  Custom CSS Example Let\u0026rsquo;s make headers navy colored.\nCreate assets/css/reveal_custom.css with:\n.reveal section h1, .reveal section h2, .reveal section h3 { color: navy; }  Questions? 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