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Published August 28, 2017 | Published + Supplemental Material
Journal Article Open

Aftershocks driven by afterslip and fluid pressure sweeping through a fault-fracture mesh


A variety of physical mechanisms are thought to be responsible for the triggering and spatiotemporal evolution of aftershocks. Here we analyze a vigorous aftershock sequence and postseismic geodetic strain that occurred in the Yuha Desert following the 2010 M_w 7.2 El Mayor-Cucapah earthquake. About 155,000 detected aftershocks occurred in a network of orthogonal faults and exhibit features of two distinct mechanisms for aftershock triggering. The earliest aftershocks were likely driven by afterslip that spread away from the main shock with the logarithm of time. A later pulse of aftershocks swept again across the Yuha Desert with square root time dependence and swarm-like behavior; together with local geological evidence for hydrothermalism, these features suggest that the events were driven by fluid diffusion. The observations illustrate how multiple driving mechanisms and the underlying fault structure jointly control the evolution of an aftershock sequence.

Additional Information

© 2017 American Geophysical Union. Received 17 JUN 2017; Accepted 2 AUG 2017; Accepted article online 7 AUG 2017; Published online 19 AUG 2017. We thank the field teams from UC Riverside and UC Santa Barbara who installed the temporary stations in the Yuha Desert. The paper benefitted from constructive comments by two anonymous reviewers and Shiqing Xu. All waveform data used are available at the Southern California Earthquake Data Center (scedc.caltech.edu), and all GPS data used are available at SOPAC (sopac.ucsd.edu). The earthquake catalog produced is available in supporting information as Data Set S1. This research was supported by USGS/NEHRP grant G16AP00147; NSF awards: EAR-1550704 and EAR-1551411; and by the Southern California Earthquake Center, which is funded by NSF Cooperative Agreement EAR-1033462 and USGS Cooperative Agreement G12 AC20038.

Attached Files

Published - Ross_et_al-2017-Geophysical_Research_Letters.pdf

Supplemental Material - grl56277-sup-0001-2017GL074634_ms01.mp4

Supplemental Material - grl56277-sup-0002-2017GL074634_ms02.mp4

Supplemental Material - grl56277-sup-0003-2017GL074634_ds01.txt

Supplemental Material - grl56277-sup-0004-2017GL074634_SI.pdf

Supplemental Material - grl56277-sup-0005-2017GL074634_SI.pdf

Supplemental Material - grl56277-sup-0006-2017GL074634_SI.pdf

Supplemental Material - grl56277-sup-0007-2017GL074634_SI.pdf


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August 19, 2023
October 26, 2023