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Summary: Episodic Tremor and Slip along the length of Cascadia
Observations and implications for seismic hazard
Richard Allen* UC Berkeley
Michael Brudzinski Miami University
Presentation to National Earthquake Predication Evaluation Council, May 18th 2007.
Segmentation of ETS characteristics and events
· Three zones with similar recurrence intervals: 14 ± 2 months in the north, 19 ± 4 months
in the central region and 10 ± 2 months in the south.
· There are around seven segments which can host distinct ETS events.
· From 2000 to 2006 there where 22 months during which an ETS event occurred, i.e. an
average of one event every 3.3 months.
Structural control of ETS
· The three zones correlate with geologic terrain of the continental plate.
· The seven segments correlate with forearc basins interpreted as indicators of megathrust
structure.
Implications for seismic hazard
· The slow slip events likely increase stress on the megathrust.
· The correlation between ETS segments and megathrust asperities is consistent with a
link between ETS and megathrust processes.
· While this illustrates the importance of future research, public warnings every ~3
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