Analysis of Spatial and Temporal Seismicity Patterns within Arizona During the Deployment of the EarthScope USArray Transportabl

Analysis of Spatial and Temporal Seismicity Patterns within Arizona During the Deployment of the EarthScope USArray Transportable Array (March 2006 - April 2009) Figure Captions: Left: Locations of three earthquake swarms investigated as part of this study (yellow circles), USArray Transportable Array stations (red triangles), and the geologic/physiographic provinces of Arizona. Right Column: Google Earth screen captures of events from USArray ANF monthly archives (white circles), new events located as part of this study (yellow circles), and USArray TA stations (blue circles). Top Right: Roosevelt Swarm - 62 detections from 6/21/2007 to 6/28/2007 with 20 located events (3+ stations). Mag = 1.6 to 2.5 ml; Avg Depth = 3.8 km; Peak Activity = 10 events/hour. Middle Right: Uinkaret Swarm: 345 detections from 12/4/2007 to 12/17/2007 with 20 located events (3+ stations). Mag = 0.7 to 3.2 ml; Avg Depth = 13.5 km; Peak Activity = 18 events/hour. Bottom Right: Shonto Swarm: 172 detections from 8/29/2008 to 9/29/2008 with 34 located events (3+ stations). Mag = 0.8 to 2.8 ml; Avg Depth = 5.8 km; Peak Activity = 6 events/hour.
Monitoring earthquake activity across the state of Arizona has historically been restricted by a paucity of regional seismic stations. Prior to 2006, earthquakes within Arizona were located at a rate of less than 30 events per year, presenting significant challenges for studies linking seismic activity and lithospheric strain accommodation. In this study, we utilize broadband seismic data recorded within Arizona by the EarthScope USArray Transportable Array (TA) ( to improve the characterization of the sources of tectonic strain accumulation and the mechanisms by which it is released. We built a Google Earth KMZ of global event data using EarthScope ANF monthly event archives to examine the spatial and temporal distribution of seismicity within Arizona during the deployment of the USArray TA. To date, we have identified 12 areas of seismicity within Arizona that exhibit event swarms with clear spatial and temporal correlations. We analyzed waveform data using the Antelope Environmental Data Collection Software package. We examined data from 8 TA stations nearest to each of 3 case studies and hand-picked P and S arrivals to generate a catalog of events for each swarm. We used a 1-5 Hz bandpass filter to detect events and a 0.3 Hz high-pass filter or no filter to pick arrivals. We present preliminary swarm characterization for these three case studies, which were chosen due to their distinctly different tectonic settings. (1) The linear-trending (NNE-SSW) Roosevelt Swarm is located within the Arizona Transition Zone and is adjacent to Roosevelt Lake, a ~35 km long reservoir on the Salt River with a maximum depth of ~100 m. (2) The spatially clustered Uinkaret Swarm is geologically located beneath the Uinkaret Volcanic Field on the north rim of the Grand Canyon (last known eruption ~1,100 years ago). The swarm is juxtaposed between 2 notable Quaternary faults (Hurricane and Toroweap) and is located within the Northern Arizona Seismic Belt along the western tectonic boundary of the Colorado Plateau. (3) The spatially clustered Shonto Swarm is geologically located within the Colorado Plateau. The nearest volcanic field is located ~47 km to the NE, and no known faults have been identified in the vicinity of this swarm.
Acknowledgements: Financial support for this project came from U.S. National Science Foundation grant EAR-0548288 and the Federal Emergency Management Agency (FEMA). A huge thanks to the USArray Transportable Array team for installing and maintaining the stations used for this study. Waveform and Antelope database data were provided by Frank Vernon (USArray Array Network Facility) and the IRIS Data Management Center. Thanks also to the USArray Array Network Facility for a preliminary USArray event catalog. Historical Arizona earthquake database was provided by the Arizona Earthquake Information Center and the Arizona Integrated Seismic Network. Aerial photographs and Google Earth interface provided by Google.</p>


No comments yet.



Welcome to the IRIS Image Gallery – a diverse collection of photographs and visuals that encompass the range and breadth of seismology and the seismological community.

Please browse through our albums. These low and medium-resolution images can be freely used for personal and educational/academic purposes, but we request you recognize the image contributor by including in your product or presentation the credit displayed with each image.

More information is available in the Image Use Agreement.

If you have any comments, questions, or suggestions related to the IRIS Image Gallery, you can send them to

Photo info

Popular tags