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Published August 28, 2018 | Supplemental Material + Published
Journal Article Open

Microseismicity Simulated on Asperity-Like Fault Patches: On Scaling of Seismic Moment With Duration and Seismological Estimates of Stress Drops


Observations show that microseismic events from the same location can have similar source durations but different seismic moments, violating the commonly assumed scaling. We use numerical simulations of earthquake sequences to demonstrate that strength variations over seismogenic patches provide an explanation of such behavior, with the event duration controlled by the patch size and event magnitude determined by how much of the patch area is ruptured. We find that stress drops estimated by typical seismological analyses for the simulated sources significantly increase with the event magnitude, ranging from 0.006 to 8 MPa. However, the actual stress drops determined from the on‐fault stress changes are magnitude‐independent and ~3 MPa. Our findings suggest that fault heterogeneity results in local deviations in the moment‐duration scaling and earthquake sources with complex shapes of the ruptured area, for some of which stress drops may be significantly (~100–1,000 times) underestimated by the typical seismological methods.

Additional Information

© 2018 American Geophysical Union. Received 10 MAY 2018; Accepted 19 JUL 2018; Accepted article online 25 JUL 2018; Published online 17 AUG 2018. This study was supported by the National Science Foundation (grants EAR‐1520907 and 1724686), United States Geological Survey (grant G16AP00117), Southern California Earthquake Center (SCEC, funded by NSF Cooperative Agreement EAR1033462 and USGS Cooperative Agreement G12AC20038), and the Postdoctoral Research Abroad Program 105‐2917‐I‐564‐015 of the Ministry of Science and Technology in Taiwan. This is SCEC contribution 8066. We thank Emily E. Brodsky, Egill Hauksson, Junle Jiang, Hiroo Kanamori, Yoshihiro Kaneko, Valère R. Lambert, Zachary E. Ross, and Natalie Schaal for helpful discussions. We also thank the Associate Editor and two anonymous reviewers for insightful comments that helped us improve the manuscript. The data used are listed in the references, tables, and supporting information.

Attached Files

Published - Lin_et_al-2018-Geophysical_Research_Letters.pdf

Supplemental Material - grl57812-sup-0001-supporting-information_20180801-source.docx


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August 19, 2023
October 18, 2023