Separation of intrinsic and scattering Q by envelope inversion

Qopen is a script in seismology that estimates shear wave scattering and intrinsic attenuation parameters by inversion of seismogram envelopes.

How it works

The method is described in the following publication:

Tom Eulenfeld and Ulrich Wegler (2016), Measurement of intrinsic and scattering attenuation of shear waves in two sedimentary basins and comparison to crystalline sites in Germany, Geophysical Journal International, 205(2), 744-757, doi:10.1093/gji/ggw035. [pdf]

Alternatively, have a look at our poster presented at the 2015 Annual Meeting of the DGG.

How to use it

Installation

Since version 2, Qopen runs on Python3 only. If you want to use Qopen with Python2 use version 1.x.

Dependencies of Qopen are:

• ObsPy>=1.0
• NumPy, SciPy and matplotlib (itself dependencies of ObsPy)
• statsmodels

Installation with conda :: It's probably best to install ObsPy first and then let pip take care of the rest. Install Qopen and its dependencies with

conda --add channels conda-forge
conda create -n qenv matplotlib numpy scipy obspy statsmodels
conda activate qenv
pip install qopen

Qopen provides the scripts qopen, qopen-rt and qopen-runtests. The installation can be tested with:

qopen-runtests

Tutorial

The code is run by the installed command line script qopen. A tutorial can be created with the appropriate flag:

qopen --tutorial

This command copies an example configuration file in JSON format and the corresponding data files into the current directory. The configuration file is heavily commented and should be rather self-explanatory. Now you can perform the inversion by simply running

qopen

which will calculate the results and create different plots.

Use your own data

To use the script with your own data you need 1. an inventory (StationXML or other ObsPy readable format) of your stations, 2. the earthquake catalog (QuakeML or other ObsPy readable format) preferable with P and S picks and 3. the waveforms. Waveforms may exist in data files of various formats or can be fetched from a webservice. A custom solution for waveform retrieval is also possible (e.g. mixing of data files and web requests). An example configuration file can be created with

qopen --create-config

This file has to be adapted to your needs (time window selection, etc.). The inversion is started by simply running qopen again.

Use Qopen in Python scripts

To call Qopen from Python do e.g.

from qopen import run
run(conf='conf.json')

All configuration options in conf.json can be overwritten by keyword arguments passed to run().

Please also consult the API documentation.

Get help and discuss

The seistools mailing list can be used to contact other users and developers.

A somewhat advanced example using the Qopen package: USAttenuation.