A geophysical tour of mid-ocean ridges

Instructor: Leonardo Uieda

Mid-ocean ridges are the places where the oceanic crust and lithosphere are born. They are large mountain ranges in the deep ocean, stretching all around the globe and with heights rivalling that of the tallest mountains on land. Ridges are also a key part of plate tectonics, a major component of the biogeochemical cycle of the oceans, and the home of unique biological communities.

In this tutorial, we'll study the mid-ocean ridges through the lens of geophysics. We'll use open geophysical data (gravity, bathymetry, lithospheric age) and open-source Python tools to try to answer questions like: How do ridges stay so tall? Are they in isostatic equilibrium? Why do ocean basins get deeper as they age? Along the way, we'll also learn how to translate into code the physical models of the cooling of the lithosphere so that we can compare their predictions with our data.

	Info
What	Tutorial for Transform2022
When	Wednesday 27 April 2022 08:00-10:00 UTC
Slack (Q&A)	Software Underground channel #t22-wed-mor-geophysics
Live stream	https://www.youtube.com/watch?v=NzJmRlJCNbQ
Level requirement	Intermediate Python coding experience: Learner has an understanding of variables, loops, and functions as well as the basics of the Scipy stack (numpy and matplotlib).
Conda environment	t22-wed-mor-geophysics
Notebook	mid-ocean-ridge-geophysics.ipynb
Notebook (empty version)	mid-ocean-ridge-geophysics-empty.ipynb
Run online

🧑🏿‍💻 How to take part

Transform is an fully online event. You can participate either synchronously (live) or asynchronously (any time in the future).

Synchronous:

1. ⚠️ Before the tutorial ⚠️:
   1. Setup your computer (see below).
   2. Sign up for the Software Underground Slack.
2. Connect to the YouTube livestream at the tutorial time and hop on to the #t22-wed-mor-geophysics channel on Slack as well.
3. Follow along with the tutorial on your computer (I'll write the code live). I'd recommend having your Jupyter notebook and the livestream side-by-side.
4. If you have any questions, post them on the Slack and we'll get to them.

Asynchronous:

1. Setup your computer (see below).
2. Open the YouTube recording.
3. Follow along with the tutorial on your computer (I'll write the code live). I'd recommend having your Jupyter notebook and the livestream side-by-side.
4. If you have any questions, post them on the Software Underground Slack (make sure you mention which tutorial you're asking about).

🚶🏿‍♀️ How to follow along

I will be explaining things and typing out code live in a Jupyter notebook. To follow along with the tutorial, you have 2 options:

1. Type out the code with me as I go along.
   • Pros: Keeps you from getting distracted, builds muscle memory, and ensures you follow my reasoning.
   • Cons: It can be difficult to listen and type at the same time, particularly if you encounter an error.
   • How to do it: Download the "empty" version of the notebook (links above) that has most of the code removed. Open this and type along with me.
2. Run the code that is already written along with me.
   • Pros: You don't have to match my typing so it's one less thing to worry about.
   • Cons: Can get distracted or not fully understand how things are built up.
   • How to do it: Download the "full" version of the notebook (links above) that has the full code for the tutorial. Read the code as I type along and run the code cells when I do.

There is no right way to do it so you'll have to try what works best for you.

My personal recommendation: Download both notebooks and start by trying to type along with me in the empty version. If you miss anything or have trouble keeping up, either copy it from the full notebook or switch to that one entirely. With the video being on YouTube, you can always pause or slow it down so I highly encourage trying to type things out for yourself.

👩‍🎓 Learner profile

This tutorial is designed with learners of the following profile.

This does not mean that you need to fit this profile in order to take part. It is meant only to communicate what is our starting point for building out the content of the tutorial.

• Undergraduate later in their studies or postgraduate in Earth Sciences.
• Has takes advanced level mathematics (summations, exponentials, trigonometric functions) and has had some exposure to calculus (differential equations).
• Is able to write Python code to analyze data, make figures, etc but not necessarily studied software development.
• Knows the basics of plate tectonic theory and global geology and geophysics, including the concept of isostatic equilibrium.

💻 Computer setup

For this tutorial, you'll need to have a specific Python environment setup. The particular software that is required is listed in the environment.yml file. Follow the instructions below to get set up.

Step 1: Download a Python distribution

You'll need either one of:

• Miniforge (preferred for Linux/Mac users)
• Miniconda (preferred for Windows users)
• Anaconda

If you have any of these installed already, you don't need to reinstall or switch.

Step 2: Create the tutorial environment

This step installs all of the extra things we need for the tutorial. It does so in a separate conda environment to avoid messing with your Python installations.

1. Download the environment.yml file to your computer.
2. Open a terminal (Linux/Mac) or Anaconda Prompt (Windows).
3. The following steps should be done in the terminal/prompt:
   1. Navigate to the folder that has the downloaded environment.yml file (if you don't know how to do this, take a moment to read the Software Carpentry lesson on the Unix shell).
   2. Type out the command conda env create --file environment.yml and hit Enter to create the conda environment (this will download and install all of the packages used in the tutorial so it could take a while).

If everything went smoothly, you should now have a conda enviroment called t22-wed-mor-geophysics which has all our software installed!

Step 3: Activate the environment and launch Jupyter

Now that everything has been installed, we can finally start Jupyter and get to work!

This is the only step that needs to be repeated whenever you stop working on the tutorial and come back. The previous steps only need to be done once.

In your terminal or Anaconda Prompt, run the following (type it out and hit Enter):

1. cd (return to your home folder)
2. conda activate t22-wed-mor-geophysics (activate the conda environment)
3. jupyter lab (start Jupyter Lab)

This should open your browser and load Jupyter Lab.

Note for Windows users: If Internet Explorer opens and you only get a blank page, this is because Jupyter Lab does not work with Internet Explorer. To get around this, install Firefox, Chrome, or any other browser and make it your default browser. Close your terminal/prompt and repeat the steps above.

🧑‍🏫 For instructors

The tutorial is designed to be taught as a 2 hour session with live-coding. To do so, create a copy of the notebook and delete all or most of the code cells (it's OK to leave some in to allow more time in the tutorial).

Type in the code as you explain what you're doing. This will help you control your pacing and avoid going too fast. It also opens up the opportunity for you to make mistakes and teach students how to identify and solve them.

Ideally, have students follow along on their own computers, typing in the code with you. Make sure you also share a copy of the pre-filled notebook with students so that they can choose to not type and listen at the same time.

⚖️ License

The original material for this tutorial can be found at leouieda/transform2022. Comments, corrections, and additions are welcome.

All source code is made available under the BSD 3-clause license. You can freely use and modify the code, without warranty, so long as you provide attribution to the authors.

Unless otherwise specified, all figures and Jupyter notebooks are available under the Creative Commons Attribution 4.0 License (CC-BY).

The full text of these licenses is provided in the LICENSE.txt file.