core.match_filter.detection

Functions for network matched-filter detection of seismic data.

Designed to cross-correlate templates generated by template_gen function with data and output the detections.

copyright:EQcorrscan developers. license:GNU Lesser General Public License, Version 3 (https://www.gnu.org/copyleft/lesser.html)

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class eqcorrscan.core.match_filter.detection.Detection(template_name, detect_time, no_chans, detect_val, threshold, typeofdet, threshold_type, threshold_input, chans=None, event=None, id=None)

Bases: object

Single detection from detection routines in eqcorrscan. Information required for a full detection based on cross-channel correlation sums.

Parameters:

• template_name (str) – The name of the template for which this detection was made.
• detect_time (obspy.core.utcdatetime.UTCDateTime) – Time of detection as an obspy UTCDateTime object
• no_chans (int) – The number of channels for which the cross-channel correlation sum was calculated over.
• detect_val (float) – The raw value of the cross-channel correlation sum for this detection.
• threshold (float) – The value of the threshold used for this detection, will be the raw threshold value related to the cccsum.
• typeofdet (str) – Type of detection, STA, corr, bright
• threshold_type (str) – Type of threshold used for detection
• threshold_input (float) – Threshold set for detection, relates to threshold according to the threshold_type.
• chans (list) – List of stations for the detection
• event (obspy.core.event.event.Event) – Obspy Event object for this detection, note that this is lost when writing to a Detection objects to csv files using eqcorrscan.core.match_filter.Detection.write()
• id (str) – Identification for detection (should be unique).

Methods

copy()	Returns a copy of the detection.
extract_stream(stream, length, prepick)	Extract a cut stream of a given length around the detection.
write(fname[, append])	Write detection to csv formatted file.

__init__(template_name, detect_time, no_chans, detect_val, threshold, typeofdet, threshold_type, threshold_input, chans=None, event=None, id=None)

Main class of Detection.

copy()

Returns a copy of the detection.

Returns:Copy of detection

extract_stream(stream, length, prepick)

Extract a cut stream of a given length around the detection.

Parameters:

• stream (obspy.core.stream.Stream) – Stream of data to cut from
• length (float) – Length of data to extract in seconds.
• prepick (float) – Length before the expected pick on each channel to start the cut stream in seconds.

Return type:

obspy.core.stream.Stream

write(fname, append=True)

Write detection to csv formatted file.

Will append if append==True and file exists

Parameters:

• fname (str) – Full path to file to open and write to.
• append (bool) – Set to true to append to an existing file, if True and file doesn’t exist, will create new file and warn. If False will overwrite old files.

Functions

eqcorrscan.core.match_filter.detection.read_detections(fname, encoding='UTF8')

Read detections from a file to a list of Detection objects.

Parameters:

• fname (str) – File to read from, must be a file written to by Detection.write.
• encoding (str) – Encoding used for detection file.

Returns:

list of eqcorrscan.core.match_filter.Detection

Return type:

list

Note

eqcorrscan.core.match_filter.detection.Detection’s returned do not contain Detection.event

eqcorrscan.core.match_filter.detection.write_catalog(detections, fname, format='QUAKEML')

Write events contained within detections to a catalog file.

Parameters:

• detections (list) – list of eqcorrscan.core.match_filter.Detection
• fname (str) – Name of the file to write to
• format (str) – File format to use, see obspy.core.event.Catalog.write for supported formats.

eqcorrscan.core.match_filter.detection.get_catalog(detections)

Generate an obspy.core.event.Catalog from list of Detection’s.

Parameters:detections (list) – list of eqcorrscan.core.match_filter.Detection Returns:Catalog of detected events. Return type:obspy.core.event.Catalog

Warning

Will only work if the detections have an event associated with them. This will not be the case if detections have been written to csv format using eqcorrscan.core.match_filter.Detection.write() and read back in.