Python tool for seismic waveform cross-correlation
PyWCC version 0.1.1 is a tool to compute seismic waveform cross-correlation on single- or multiple-component seismic data across a network of seismic sensors. PyWCC correlates waveform data templates with continuous seismic data, associates the resulting detections, identifies the template with the highest cross-correlation coefficient, and outputs a catalog of detections above a user-defined absolute cross-correlation threshold value. A note on the correlation: PyWCC computes cross-correlations in the frequency-domain for increased computational speed.
PyWCC runs on Python 2.7 and currently has the following major package dependencies: numpy, obspy, python, scipy
These dependencies can be easily installed via Anaconda. PyWCC 0.1.1 has been tested using numpy 1.11.1, obspy 1.0.2, and scipy 0.17.1.
Once dependencies are installed and PyWCC is downloaded, PyWCC can be run from the command line via:
/anaconda/bin/python /PATH/TO/FILE/waveform_cc.py /PATH/TO/FILE/InputFile
or from a Matlab prompt via:
[status, out] = system(‘/anaconda/bin/python /PATH/TO/FILE/waveform_cc.py /PATH/TO/FILE/InputFile’)
where a zero value of the status variable indicates the successful completion of the command and the out variable contains any status messages printed to screen.
Format of InputFile:
- pre_ot Seconds prior to template zero-time (origin-time) to include in template
- post_ot Seconds following template zero-time (origin-time) to include in template
- bp_low Bandpass filter low corner
- bp_high Bandpass filter high corner
- dec Decimation factor for sample rate. Must be integer value.
- cc_thr Absolute cross-Correlation threshold
- sta_l List of stations to include in analysis, separated by a space
- comp_l List of components to include in analysis, separated by a space
- data_dir Path to continuous seismic data directory. Default=‘./ContinuousData’
- out_dir Path to output directory. Default=‘./OutputFiles’
- temp_dir Template catalog file, inclusive of PATH. Default=‘./TemplateCatalog’
- templ_file Path to template data directory. Default=‘./TemplateData’
- verbose Verbose option True/[False]. If True will output raw data file as well as final data file and will also print status messages to screen.
Template catalog file has form: TEMPLATE_NAME YYYY/MM/DD HH:MM:SS.MMM LAT LON DEPTH
- YYYY year
- MM month
- DD day
- HH hour
- MM minute
- SS seconds
- MMM decimal seconds
- LAT latitude of template event
- LON longitude of template event
- DEPTH depth of template event
PyWCC output catalog file has form: YYYY/MM/DD HH:MM:SS.MMMMMM LAT LON DEPTH 2 DET:CC
- LAT latitude of the template DET, taken from the Template Catalog
- LON longitude of the template DET, taken from the Template Catalog
- DEPTH depth of the template DET, taken from the Template Catalog
- "2" PyWCC detection catalog flag
- DET template with the highest correlation.
- CC cross-correlation coefficient between the template DET and the new detection
Raw template waveform data should include data before and after the template start and end times to accommodate possible filter effects. The template waveform data should have accurate header information: network, station, location, and channel codes. These trace identifiers should be exactly the same as those in the continuous data headers.
An example test using seismic data from the Bradys Hot Springs geothermal field is included in the directory ./example. Waveform data, metadata, or data products for this study were accessed through the Induced Seismicity Data Website at the Lawrence Berkeley National Laboratory which is supported by the U.S. DOE Office of Geothermal Technology.
This work was supported by the U.S. Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy (EERE), Geothermal Technologies Office (GTO). This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.