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Migration characteristics of seismic tremors in the northern Cascadia margin
Author(s) -
Kao Honn,
Shan ShaoJu,
Rogers Garry,
Dragert Herb
Publication year - 2007
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2006gl028430
Subject(s) - geology , subduction , seismology , induced seismicity , episodic tremor and slip , north american plate , plate tectonics , slip (aerodynamics) , tectonics , physics , thermodynamics
Seismic waveforms from a dense regional array were analyzed to study episodic tremor‐and‐slip (ETS) events in northern Cascadia. The April 2005 episode occurred mostly in northern Vancouver Island (VI) where the Explorer plate subducts beneath the North America plate, while the May 2005 episode was mainly in middle VI. All tremor occurrences are positively correlated with the presence of subducted slabs. Besides the “steady” along‐strike migration and “halting” behavior found in previous ETS events, a new pattern (“jumping”) is found this time. Visual inspection of previous seismic records suggests that the jumping behavior is probably common to ETS tremors in all regions of VI. The majority of tremors occurred between 25 and 45 km depth in places where local seismicity is sparse or absent. Our observations are compatible with the interpretation that fluids released from dehydration of subducted materials are involved in tremor generation.