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Seismicity within Arizona during the deployment of the EarthScope USArray transportable array

Jeffrey S. Lockridge, Matthew J. Fouch and J. Ramon Arrowsmith
Seismicity within Arizona during the deployment of the EarthScope USArray transportable array
Bulletin of the Seismological Society of America (August 2012) 102 (4): 1850-1863


A detailed record of earthquake frequency and distribution is essential to understanding regional tectonic strain and seismic hazard, particularly in regions of low, but significant, seismicity levels. Comprehensive analyses of seismicity within Arizona have not been previously possible due to a lack of seismic stations in many regions, contributing to the perception that earthquakes within Arizona are rare and generally limited to the north-central and northwestern portions of the state. The EarthScope USArray Transportable Array (TA) was deployed within Arizona from April 2006 to March 2009 and provided the opportunity to examine seismicity on a statewide scale. In this study, we developed a streamlined workflow for producing a comprehensive earthquake catalog using TA data. We combined our new catalog with historical earthquake catalogs from several sources to produce the first comprehensive historical earthquake catalog for the state of Arizona. The TA-derived catalog is complete to local magnitude (M (sub L) ) approximately 1.2, contains crustal events as small as M (sub L) 0.0, and includes events located within several previously unidentified areas of seismic activity in Arizona. We also identified 16 earthquake clusters, many of which have swarmlike behavior. These earthquake clusters account for 42% of the events identified during the study period, and they occur in all physiographic, geophysical, and tectonic settings. We suggest that swarms and clusters, such as those documented in this study, may represent an important mechanism for small-scale tectonic strain release within intraplate regions with otherwise apparently low seismicity levels. Online Material: Figures comparing earthquake depth to physiographic province, elevation, crustal thickness, and heat flow; data tables including earthquake catalogs and velocity models; and an introductory User's Guide to the Antelope Environmental Data Collection Software suite.

ISSN: 0037-1106
EISSN: 1943-3573
Serial Title: Bulletin of the Seismological Society of America
Serial Volume: 102
Serial Issue: 4
Title: Seismicity within Arizona during the deployment of the EarthScope USArray transportable array
Affiliation: Arizona State University, School of Earth and Space Exploration, Tempe, AZ, United States
Pages: 1850-1863
Published: 201208
Text Language: English
Publisher: Seismological Society of America, Berkeley, CA, United States
References: 30
Accession Number: 2013-009326
Categories: Seismology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. geol. sketch maps
N31°15'00" - N37°00'00", W115°00'00" - W109°00'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, Copyright, Seismological Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201307
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