Please use this identifier to cite or link to this item: http://hdl.handle.net/2122/6115
AuthorsMcCausland, W. A.* 
Creager, K. C.* 
La Rocca, M.* 
Malone, S. D.* 
TitleShort‐term and long‐term tremor migration patterns of the Cascadia 2004 tremor and slow slip episode using small aperture seismic arrays
Issue Date2010
Series/Report no./115(2010)
DOI10.1029/2008JB006063
URIhttp://hdl.handle.net/2122/6115
Keywordstremor migration
Cascadia 2004
Subject Classification04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics 
04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring 
04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis 
04. Solid Earth::04.07. Tectonophysics::04.07.04. Plate boundaries, motion, and tectonics 
AbstractTectonic tremor has been recorded at many subduction zones, including the Nankai, Cascadia, Mexican, and Alaskan subduction zones. This study, the first to use small aperture seismic arrays to track tremor, deployed three small aperture seismic arrays along the Cascadia subduction zone during a tremor and slow slip episode in July 2004. The tremor was active during virtually all (up to 99%) minutes of the analyzed tremor episode using 5 min sample windows. Individual wave phases were tracked across the arrays and used to derive slowness vectors. These were compared with slowness vectors computed from a standard layered Earth model to derive tremor locations. Locations were stable within a volume roughly 250 km2 in epicenter and 20 km in depth for hours to days before moving to a new volume. The migration between volumes was not smooth, and the movement of the sources within the volume followed no specific pattern. Overall migration speeds along the strike of the subduction zone were between 5 and 15 km/d; smaller scale migration speeds between volumes reached speeds up to 2 km/min. Uncertainties in the best locations were 5 km in epicenter and 10 km in depth. For this data set and processing methodology, tremor does not locate predominately on the primary subduction interface. Our favored model for the generation of tectonic tremor signals is that the tremor is triggered by stress and fluid pressure changes caused by slow slip and is composed, at least in part, of low‐frequency earthquakes broadly distributed in location
DescriptionAn edited version of this paper was published by AGU. Copyright (2010) American Geophysical Union.
Appears in Collections:Papers Published / Papers in press

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