summary | prerequisites | setup | resources | license

Transform 2021: Inversion for Geologists

	Info
When	Tuesday, April 20 • 20:00 - 22:00 UTC
Slack	Software Underground channel t21-tue-inversion-for-geologists
YouTube	https://youtu.be/5MiaebDwWUQ
conda environment	t21-tue-simpeg
Slides	SimPEG Transform presentation

Team

• Seogi Kang (Instructor)
• Lindsey Heagy
• Doug Oldenburg
• Dom Fournier
• Joe Capriotti
• Dieter Werthmüller
• and the SimPEG contributors

Before the tutorial

Make sure you've done these things before the tutorial on Tuesday:

1. Sign-up for the Software Underground Slack
2. Join the channel t21-tue-inversion-for-geologists. This is where all communication will happen.
3. Set up your computer (instructions below). We will not have time to solve many computer issues during the tutorial so make sure you do this ahead of time. If you need any help, ask at the t21-tue-inversion-for-geologists channel on Slack.
4. If you have some data you'd like to process, please have it ready and make sure you can load it with pandas or numpy. You'll have some time at the end of the tutorial to work on your own data.

Summary

This repo contains the notebooks and tutorial resources for the Transform 2021 tutorial on Inversion for Geologists. In this tutorial, we will provide fundamental concepts about the inversion framework. As a motivating example, we will use the magnetic data acquired at Raglan deposits in Northern Quebec, Candada. About 20 years ago, this magnetic data set was inverted in 3D (sort of the first time), and resulting susceptiblity model played an imporant role for spotting a drill hole, which found mineralized zones.

Starting from field data in a text file we will learn how to

• load those data into SimPEG
• construct a survey object that contains the geometry of the sources and receivers
• set up and run a forward simulation
• define the inverse problem consisting of a data misfit and regularization
• run an inversion and discuss inversion strategies

Then, we will work with a synthetic example to

• demonstrate how to explore aspects of the physics with SimPEG
• explore the role and influence of parameters used in an inversion

Prerequisites

Software

• Some knowledge of Python is assumed.
• All coding will be done in Jupyter notebooks. I'll explain how they work briefly but it will help if you've used them before.
• We'll use numpy, matplotlib, and ipywidgets You don't need to be an expert in these tools but some familiarity will help.

Geophysical Inversions

• This tutorial will focus on providing fundamental concepts of the geophysical inversion. I do not assume an extensive background in inversions, but it will help if you have been introduced to some concepts. The Inversion Module provides a nice overview.
• As a motivating example, I will use magnetic mehod. I'll explain the basic principles, but if these are new to you, then I would recommend taking a read through the Magnetics.

Usage

There are a few things you'll need to follow the tutorial:

1. A working Python installation (Anaconda or Miniconda)
2. The SimPEG conda environment installed
3. A web browser that works with Jupyter (basically anything except Internet Explorer)

To get things setup, please do the following.

If you have any trouble, please ask for help in the t21-tue-inversion-for-geologists channel on the Software Underground slack.

Windows users: When you see "terminal" in the instructions, this means the "Anaconda Prompt" program for you.

Step 1: Python

Follow the general instructions for Transform2021: https://www.youtube.com/playlist?list=PLgLft9vxdduAW-jmhYqXvtfGYJS6v2FjM

This will get you a working Python 3 installation with the conda package manager. If you already have one, you can skip this step.

Step 2: Download the SimPEG tutorials

To access the notebooks, there are 3 options (in order of preference):

1. Use git to clone this repository
2. From GitHub, you can use the download option to download this repository as a zip file (follow all instructions below, replacing the git clone step with download and unzip the zip file with the repository contents.
3. You can run the notebooks online with binder through: https://mybinder.org/v2/gh/simpeg/transform-2021-simpeg/master

To clone this repository, open up a terminal and navigate to where you want this repository stored on your computer.

Then run

git clone https://github.com/simpeg/transform-2021-simpeg.git

to clone the repository, and cd into the transform-2021-simpeg directory

cd transform-2021-simpeg

Step 3: Create the SimPEG tutorial conda environment

From inside of the transform-2021-simpeg repository, create the t21-tue-simpeg conda environment

conda env create -f environment.yml

and activate the environment

conda activate t21-tue-simpeg

Step 4: Launching the notebooks

Once you have activated the conda environment, you can launch the notebooks

jupyter notebook

Jupyter will then launch in your web-browser.

If you are able to open any one of the notebooks and run the first cell, then you should be good to go! If you run into issues, please post in the #t21-tue-simpeg slack channel.

Resources

Resources on Geophysics and Inversions

• Geophysics for Practicing Geoscientists
• Inversion Module
• SimPEG

Resources on SimPEG

• Docs
• Discourse
• Slack
• This Tutorial

License

All code and text in this repository is free software: you can redistribute it and/or modify it under the terms of the MIT License. A copy of this license is provided in LICENSE.