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Published October 2015 | Supplemental Material + Published
Journal Article Open

An objective method for the assessment of fluid injection-induced seismicity and application to tectonically active regions in central California


Changes in seismicity rates, whether of tectonic or of induced origin, can readily be identified in regions where background rates are low but are difficult to detect in seismically active regions. We present a novel method to identify likely induced seismicity in tectonically active regions based on short-range spatiotemporal correlations between changes in fluid injection and seismicity rates. The method searches through the entire parameter space of injection rate thresholds and determines the statistical significance of correlated changes in injection and seismicity rates. Applying our method to Kern County, central California, we find that most earthquakes within the region are tectonic; however, fluid injection contributes to seismicity in four different cases. Three of these are connected to earthquake sequences with events above M4. Each of these sequences followed an abrupt increase in monthly injection rates of at least 15,000 m^3. The probability that the seismicity sequences and the abrupt changes in injection rates in Kern County coincide by chance is only 4%. The identified earthquake sequences display low Gutenberg-Richter b values of ∼0.6–0.7 and at times systematic migration patterns characteristic for a diffusive process. Our results show that injection-induced pressure perturbations can influence seismic activity at distances of 10 km or more. Triggering of earthquakes at these large distances may be facilitated by complex local geology and faults in tectonically active regions. Our study provides the first comprehensive, statistically robust assessment of likely injection-induced seismicity within a large, tectonically active region.

Additional Information

© 2015 American Geophysical Union. Received 16 JAN 2015; Accepted 7 SEP 2015; Accepted article online 29 SEP 2015; Published online 21 OCT 2015. We thank Frederic Cappa, Jason Saleeby, Emily Brodsky, Tayeb Tafti and the members of the Induced Seismicity Consortium at USC for helpful discussions. We thank the statistical seismology community for the Community Online Resources for Statistical Seismicity Analysis (corssa.org) and Jeremy Zechar for providing his declustering code. This research was supported by NEHRP/USGS grants G13AP00047 and G14AP00075, and by the Southern California Earthquake Center (SCEC) under contribution number 12017. SCEC is funded by NSF Cooperative Agreement EAR-0529922 and USGS Cooperative Agreement 07HQAG0008. The utilized seismicity catalog and injection data of likely earthquake-inducing wells is available in the supporting information. The computer program for running the OISC algorithm was developed using the open-source python programming language and is available from the first author upon request.

Attached Files

Published - Goebel_et_al-2015-Journal_of_Geophysical_Research__Solid_Earth.pdf

Supplemental Material - jgrb51322-sup-0001-supinfo.txt

Supplemental Material - jgrb51322-sup-0002-supinfo.txt

Supplemental Material - jgrb51322-sup-0003-supinfo.txt

Supplemental Material - jgrb51322-sup-0004-supinfo.txt

Supplemental Material - jgrb51322-sup-0005-supinfo.txt

Supplemental Material - jgrb51322-sup-0006-supinfo.txt

Supplemental Material - jgrb51322-sup-0007-supinfo.txt

Supplemental Material - jgrb51322-sup-0008-supinfo.txt

Supplemental Material - jgrb51322-sup-0009-supinfo.pdf


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August 20, 2023
October 17, 2023