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Triggered tremor sweet spots in Alaska

Journal of Geophysical Research B: Solid Earth

By:
,
DOI: 10.1002/2013JB010273

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Abstract

To better understand what controls fault slip along plate boundaries, we have exploited the abundance of seismic and geodetic data available from the richly varied tectonic environments composing Alaska. A search for tremor triggered by 11 large earthquakes throughout all of seismically monitored Alaska reveals two tremor “sweet spots”—regions where large-amplitude seismic waves repeatedly triggered tremor between 2006 and 2012. The two sweet spots locate in very different tectonic environments—one just trenchward and between the Aleutian islands of Unalaska and Akutan and the other in central mainland Alaska. The Unalaska/Akutan spot corroborates previous evidence that the region is ripe for tremor, perhaps because it is located where plate-interface frictional properties transition between stick-slip and stably sliding in both the dip direction and laterally. The mainland sweet spot coincides with a region of complex and uncertain plate interactions, and where no slow slip events or major crustal faults have been noted previously. Analyses showed that larger triggering wave amplitudes, and perhaps lower frequencies (<~0.03 Hz), may enhance the probability of triggering tremor. However, neither the maximum amplitude in the time domain or in a particular frequency band, nor the geometric relationship of the wavefield to the tremor source faults alone ensures a high probability of triggering. Triggered tremor at the two sweet spots also does not occur during slow slip events visually detectable in GPS data, although slow slip below the detection threshold may have facilitated tremor triggering.

Geospatial Extents

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Triggered tremor sweet spots in Alaska
Series title:
Journal of Geophysical Research B: Solid Earth
DOI:
10.1002/2013JB010273
Volume
118
Issue:
12
Year Published:
2013
Language:
English
Publisher:
Wiley
Contributing office(s):
Earthquake Science Center
Description:
16 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
6203
Last page:
6218
Number of Pages:
16
Country:
United States
State:
Alaska
Other Geospatial:
Denali Fault