Systematic Detection of Clustered Seismicity Beneath the Southwestern Alps
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Beauce_2019_main_text_PREPRINT.pdf
Description
Accepted version
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3.6 MB
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Checksum (MD5)
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Author(s)
Beaucé, Eric
Frank, William B.
Paul, Anne
Campillo, Michel
Campillo, Michel Henri Paul
Hilst, Robert D.
van der Hilst, Robert D
Date Issued
November 2019
Journal
Journal of Geophysical Research: Solid Earth
Publisher
American Geophysical Union (AGU)
Citation
Beaucé, Eric et al. "Systematic Detection of Clustered Seismicity Beneath the Southwestern Alps." Journal of Geophysical Research: Solid Earth 124, 11 (November 2011): 11531-11548 © 2019 American Geophysical Union
Version
Author's final manuscript
Abstract
We present a new automated earthquake detection and location method based on beamforming (or back projection) and template matching and apply it to study the seismicity of the Southwestern Alps. We use beamforming with prior knowledge of the 3-D variations of seismic velocities as a first detection run to search for earthquakes that are used as templates in a subsequent matched-filter search. Template matching allows us to detect low signal-to-noise ratio events and thus to obtain a high spatiotemporal resolution of the seismicity in the Southwestern Alps. We describe how we address the problem of false positives in energy-based earthquake detection with supervised machine learning and how to best leverage template matching to iteratively refine the templates and the detection. We detected 18,754 earthquakes over 1 year (our catalog is available online) and observed temporal clustering of the earthquake occurrence in several regions. This statistical study of the collective behavior of earthquakes provides insights into the mechanisms of earthquake occurrence. Based on our observations, we infer the mechanisms responsible for the seismic activity in three regions of interest: the Ubaye valley, the Briançonnais, and the Dora Maira massif. Our conclusions point to the importance of fault interactions to explain the earthquake occurrence in the Briançonnais and the Dora Maira massif, whereas fluids seem to be the major driving mechanism in the Ubaye valley.
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
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Creative Commons Attribution-Noncommercial-Share Alike
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DOI of Published Version
https://doi.org/10.1029/2019jb018110
