flixha / rtm

A Python package for locating infrasound sources using reverse time migration

rtm

rtm is a Python package for locating infrasound sources using reverse time migration (RTM). Infrasound (or seismic) waveform data are back-projected over a grid of trial source locations. This implementation and some examples are detailed in Fee et al. (2021), and we ask that if you use this code you cite that paper. The code is based upon previous work by Sanderson et al. (2020) and Walker et al. (2010) and is applicable to a wide variety of network geometries and sizes. Realistic travel times can be incorporated from numerical modeling or atmospheric specifications.

References

Fee, D., Toney, L., Kim, K., Sanderson, R. W., Iezzi, A. M., Matoza, R. S., De Angelis, S., Jolly, A. D., Lyons, J. J., & Haney, M. M. (2021). Local Explosion Detection and Infrasound Localization by Reverse Time Migration Using 3-D Finite-Difference Wave Propagation. Frontiers in Earth Science, 9. https://doi.org/10.3389/feart.2021.620813

Sanderson, R. W., Matoza, R. S., Fee, D., Haney, M. M., & Lyons, J. J. (2020). Remote detection and location of explosive volcanism in Alaska with the EarthScope Transportable Array. Journal of Geophysical Research: Solid Earth, 125, e2019JB018347. https://doi.org/10.1029/2019JB018347

Walker, K. T., Hedlin, M. A. H., de Groot‐Hedlin, C., Vergoz, J., Le Pichon, A., & Drob, D. P. (2010). Source location of the 19 February 2008 Oregon bolide using seismic networks and infrasound arrays. Journal of Geophysical Research: Solid Earth, 115, B12329. https://doi.org/10.1029/2010JB007863

Installation

We recommend you install this package into a new conda environment. (Please install Anaconda or Miniconda before proceeding.) The environment must contain all of the packages listed in the Dependencies section. For ease of installation, we've provided an environment.yml file which specifies all of these dependencies as well as instructions for installing rtm itself. To install rtm in this manner, execute the following commands:

git clone https://github.com/uafgeotools/rtm.git
cd rtm
conda env create

This creates a new conda environment named rtm and installs rtm and all of its dependencies there.

The final command above installs rtm in "editable" mode, which means that you can update it with a simple git pull in your local repository. We recommend you do this often, since this code is still under rapid development.

Dependencies

uafgeotools repositories:

• waveform_collection

Python packages:

• cartopy
• GDAL
• ObsPy
• utm
• xarray

...and their dependencies, which you don't really have to be concerned about if you're using conda!

Optional (for automatic DEM downloading):

• GMT 6 (install by following the official GMT install instructions)

Usage

Documentation is available online here.

To use rtm, you must always first activate the rtm environment with:

conda activate rtm

Then, you may access the package's functions from the Python interpreter with (for example)

from waveform_collection import gather_waveforms
from rtm import define_grid

and so on. For usage examples, see the two notebooks example_local.ipynb and example_regional.ipynb.

Authors

(Alphabetical order by last name.)

David Fee
Liam Toney