Skip to Main Content
Skip Nav Destination
GEOREF RECORD

Sensitivity of full moment tensors to data preprocessing and inversion parameters; a case study from the Salton Sea geothermal field

Stephan Bentz, Patricia Martinez-Garzon, Grzegorz Kwiatek, Marco Bohnhoff and Joerg Renner
Sensitivity of full moment tensors to data preprocessing and inversion parameters; a case study from the Salton Sea geothermal field
Bulletin of the Seismological Society of America (April 2018) 108 (2): 588-603

Abstract

We investigate the source mechanisms of 80 earthquakes at the Salton Sea geothermal field in southern California with local magnitudes ranging from 2.2 to 3.8, combining data from a local network of shallow short-period borehole geophones and regional broadband seismometers. The performance of two moment tensor inversion techniques based on P-wave first-motion amplitudes and full waveforms is compared. The inversion using full waveforms is unable to reproduce the observed seismograms to a detail sufficient for successful moment tensor estimation, most likely due to small-scale heterogeneities in the crust beneath the geothermal field. Only a combination of P-wave amplitude inversion and moment tensor refinement techniques enables a robust determination of the source types. We find that most shallow earthquakes display statistically significant non-double-couple components, indicating that the ruptures involve processes other than simple shear. The largest volumetric components are inferred for events located near active injection and production wells and primarily correspond to a normal-faulting regime. In contrast, strike-slip events are dominated by shear motion, and their locations extend well beyond the reservoir. Our observations suggest that both short-term effective stress reduction and long-term reservoir depletion influence the source characteristics of the occurring seismicity. Furthermore, we highlight the necessity for a careful evaluation of the optimum moment tensor inversion technique as a prerequisite for reservoir characterization based on source properties of seismicity related to fluid injection.


ISSN: 0037-1106
EISSN: 1943-3573
Coden: BSSAAP
Serial Title: Bulletin of the Seismological Society of America
Serial Volume: 108
Serial Issue: 2
Title: Sensitivity of full moment tensors to data preprocessing and inversion parameters; a case study from the Salton Sea geothermal field
Affiliation: German Research Centre for Geosciences, Potsdam, Germany
Pages: 588-603
Published: 201804
Text Language: English
Publisher: Seismological Society of America, Berkeley, CA, United States
References: 84
Accession Number: 2018-053928
Categories: Seismology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sketch map
N32°34'60" - N33°25'00", W116°10'00" - W114°25'00"
Secondary Affiliation: Ruhr-Universitaet Bochum, DEU, Germany
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute. Abstract, Copyright, Seismological Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201813
Close Modal

or Create an Account

Close Modal
Close Modal