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Pushing the limit of earthquake detection with distributed acoustic sensing and template matching: a case study at the Brady geothermal field

Li, Zefeng and Zhan, Zhongwen (2018) Pushing the limit of earthquake detection with distributed acoustic sensing and template matching: a case study at the Brady geothermal field. Geophysical Journal International, 215 (3). pp. 1583-1593. ISSN 0956-540X. doi:10.1093/gji/ggy359.

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Template matching has been widely applied in the detection of earthquakes and other seismic events due to its power in detecting weak signals. Recent studies using synthetics have shown that application of template matching to large-N arrays can potentially detect earthquakes substantially below the noise level. Here we apply template matching to the distributed acoustic sensing (DAS) data recorded in the Brady Hot Springs geothermal field, Nevada. Using 5 catalogued events, we detect 116 events and find 68 of them well below the noise level. We confirm 112 events are true earthquakes by examining the patterns of their sensor-to-sensor cross-correlation sections. This demonstrates that the combination of DAS and template matching has capability to detect microseismicity below the noise level, which is unusual for conventional seismic arrays and methods. With the updated catalogue, we observe a surge of earthquakes during the shutdown of a geothermal power plant nearby. In addition, the rapid increases in the downhole pressure record coincide with intense swarms of earthquakes. These observations show a strong correlation between the seismicity frequencies and the downhole pressure changes. Finally, we investigate several factors that may affect the detection performance and compare different strategies for spatial down-sampling, in order to provide helpful insights for future large-N design and data processing.

Item Type:Article
Related URLs:
URLURL TypeDescription
Li, Zefeng0000-0003-4405-8872
Zhan, Zhongwen0000-0002-5586-2607
Additional Information:© The Author(s) 2018. Published by Oxford University Press on behalf of The Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model ( Accepted 2018 August 30. Received 2018 August 22; in original form 2018 April 24. Published: 03 September 2018. We are grateful to the Editor Jörg Renner, Nate Lindsey and the other anonymous reviewer for their helpful comments. We thank Kurt L. Feigl and the PoroTomo Team for making the DAS data and the downhole pressure record publically available. They can be accessed on the Geothermal Data Repository (, keyword: PoroTomo, last accessed on 2018 June 20). We thank Xiangfang Zeng for helpful discussions on data processing. This work is partially supported by the Nation Science Foundation Grant 1722879 and the Caltech Discovery Fund, and the President's and Director's Fund. The PoroTomo experiment in 2016 is supported by award DE-EE0006760 from the Geothermal Technologies Office of the U.S. Department of Energy.
Group:Center for Geomechanics and Mitigation of Geohazards (GMG), Division of Geological and Planetary Sciences, Seismological Laboratory
Funding AgencyGrant Number
Caltech Discovery FundUNSPECIFIED
Caltech President's and Director's FundUNSPECIFIED
Department of Energy (DOE)DE-EE0006760
Subject Keywords:Earthquake source observations, Induced seismicity, Seismic instruments
Issue or Number:3
Record Number:CaltechAUTHORS:20180924-090109015
Persistent URL:
Official Citation:Zefeng Li, Zhongwen Zhan; Pushing the limit of earthquake detection with distributed acoustic sensing and template matching: a case study at the Brady geothermal field, Geophysical Journal International, Volume 215, Issue 3, 1 December 2018, Pages 1583–1593,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:89887
Deposited By: Tony Diaz
Deposited On:24 Sep 2018 23:06
Last Modified:15 Nov 2022 21:41

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