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

Hauksson, Egill and Andrews, Jennifer and Plesch, Andreas and Shaw, John H. and Shelly, David R. (2016) The 2015 Fillmore Earthquake Swarm and Possible Crustal Deformation Mechanisms near the Bottom of the Eastern Ventura Basin, California. Seismological Research Letters, 87 (4). pp. 807-815. ISSN 0895-0695. http://resolver.caltech.edu/CaltechAUTHORS:20160708-101017446

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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.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1785/0220160020DOIArticle
http://srl.geoscienceworld.org/content/87/4/807PublisherArticle
http://www.seismosoc.org/Publications/SRL/SRL_87/srl_87-4_hauksson_et_al-esupp/PublisherSupplemental Materials
ORCID:
AuthorORCID
Hauksson, Egill0000-0002-6834-5051
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.
Group:Seismological Laboratory
Funders:
Funding AgencyGrant Number
USGSG15AP00095
Southern California Earthquake Center (SCEC)UNSPECIFIED
NSFEAR-1033462
USGSG12AC20038
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Southern California Earthquake Center (SCEC)6208
Record Number:CaltechAUTHORS:20160708-101017446
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20160708-101017446
Official Citation:The 2015 Fillmore Earthquake Swarm and Possible Crustal Deformation Mechanisms near the Bottom of the Eastern Ventura Basin, California Egill Hauksson, Jennifer Andrews, Andreas Plesch, John H. Shaw, David R. Shelly Seismological Research Letters Jul 2016, 87 (4) 807-815; DOI: 10.1785/0220160020
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:68917
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:08 Jul 2016 23:51
Last Modified:08 Jul 2016 23:51

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