Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published July 2016 | Published + Supplemental Material
Journal Article Open

The 2015 Fillmore Earthquake Swarm and Possible Crustal Deformation Mechanisms near the Bottom of the Eastern Ventura Basin, California

Abstract

The 2015 Fillmore swarm occurred about 6 km west of the city of Fillmore in Ventura, California, and was located beneath the eastern part of the actively subsiding Ventura basin at depths from 11.8 to 13.8 km, similar to two previous swarms in the area. Template‐matching event detection showed that it started on 5 July 2015 at 2:21 UTC with an M ∼1.0 earthquake. The swarm exhibited unusual episodic spatial and temporal migrations and unusual diversity in the nodal planes of the focal mechanisms as compared to the simple hypocenter‐defined plane. It was also noteworthy because it consisted of >1400 events of M ≥ 0.0, with M 2.8 being the largest event. We suggest that fluids released by metamorphic dehydration processes, migration of fluids along a detachment zone, and cascading asperity failures caused this prolific earthquake swarm, but other mechanisms (such as simple mainshock–aftershock stress triggering or a regional aseismic creep event) are less likely. Dilatant strengthening may be a mechanism that causes the temporal decay of the swarm as pore‐pressure drop increased the effective normal stress, and counteracted the instability driving the swarm.

Additional Information

© 2016 Seismological Society of America. Published Online 18 May 2016. We thank W. Thatcher for a comprehensive review and Thom Davis for helpful discussions. This research was supported by U.S. Geological Survey (USGS)/National Earthquake Hazards Reduction Program (NEHRP) Grant G15AP00095 and by the Southern California Earthquake Center (SCEC), which is funded by National Science Foundation Cooperative Agreement EAR‐1033462 and USGS Cooperative Agreement G12AC20038. This article is SCEC Contribution Number 6208. Google Earth imagery is used in the background of Figure 5.

Attached Files

Published - 807.full.pdf

Supplemental Material - SRL-2016020_esupp_Movie_S1.mp4

Supplemental Material - SRL-2016020_esupp_Table_S1.txt

Supplemental Material - SRL-2016020_esupp_Table_S2.txt

Supplemental Material - SRL-2016020_esupp_Table_S3.txt

Files

SRL-2016020_esupp_Table_S2.txt
Files (9.0 MB)
Name Size Download all
md5:501a09f0da2aa9648d3af4abf61e92b3
8.1 MB Download
md5:f6ac0fbd3928f8aafd4660525422de05
141.3 kB Preview Download
md5:48430bf7cd041f46e3606bf98351bb75
6.2 kB Preview Download
md5:ab9afea3c18a6b4f2f509b10ab80c35f
765.2 kB Preview Download
md5:fd1d295ac3eaddeb14a94f438580552d
25.3 kB Preview Download

Additional details

Created:
August 20, 2023
Modified:
October 20, 2023