Abstract
GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS,
VOL. 12,
Q06005,
8 PP., 2011
doi:10.1029/2011GC003559
Tiny intraplate earthquakes triggered by nearby episodic tremor and slip in Cascadia
- ETS triggers nearby earthquakes in slab
- ETS stress may concentrate at updip edge
- Starting point to calibrating risk of tremor triggering hazardous earthquakes
Department of Earth and Space Sciences, University of Washington, Box 351310, Seattle, Washington 98195, USA
Department of Earth and Space Sciences, University of Washington, Box 351310, Seattle, Washington 98195, USA
Department of Earth and Space Sciences, University of Washington, Box 351310, Seattle, Washington 98195, USA
Department of Earth and Space Sciences, University of Washington, Box 351310, Seattle, Washington 98195, USA
U.S. Geological Survey, Department of Earth and Space Sciences, University of Washington, Box 351310, Seattle, Washington 98195, USA
Episodic tremor and slip (ETS) has been observed in many subduction zones, but its mechanical underpinnings as well as its potential for triggering damaging earthquakes have proven difficult to assess. Here we use a seismic array in Cascadia of unprecedented density to monitor seismicity around a moderate 16 day ETS episode. In the 4 months of data we examine, we observe five tiny earthquakes within the subducting slab during the episode and only one more in the same area, which was just before and nearby the next ETS burst. These earthquakes concentrate along the sides and updip edge of the ETS region, consistent with greater stress concentration there than near the middle and downdip edge of the tremor area. Most of the seismicity is below the megathrust, with a similar depth extent to the background intraslab seismicity. The pattern of earthquakes that we find suggests slow slip has a more continuous temporal and spatial pattern than the tremor loci, which notoriously appear in bursts, jumps, and streaks.
Received 10 February 2011; accepted 29 March 2011; published 15 June 2011.
Citation: (2011), Tiny intraplate earthquakes triggered by nearby episodic tremor and slip in Cascadia, Geochem. Geophys. Geosyst., 12, Q06005, doi:10.1029/2011GC003559.
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