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Slip rate and tremor genesis in Cascadia

January 30, 2014

At many plate boundaries, conditions in the transition zone between seismogenic and stable slip produce slow earthquakes. In the Cascadia subduction zone, these events are consistently observed as slow, aseismic slip on the plate interface accompanied by persistent tectonic tremor. However, not all slow slip at other plate boundaries coincides spatially and temporally with tremor, leaving the physics of tremor genesis poorly understood. Here we analyze seismic, geodetic, and strainmeter data in Cascadia to observe for the first time a large, tremor-generating slow earthquake change from tremor-genic to silent and back again. The tremor falls silent at reduced slip speeds when the migrating slip front pauses as it loads the stronger adjacent fault segment to failure. The finding suggests that rheology and slip-speed-regulated stressing rate control tremor genesis, and the same section of fault can slip both with and without detectable tremor, limiting tremor's use as a proxy for slip.

Citation Information

Publication Year 2014
Title Slip rate and tremor genesis in Cascadia
DOI 10.1002/2013GL058607
Authors Aaron G. Wech, Noel M. Bartlow
Publication Type Article
Publication Subtype Journal Article
Series Title Geophysical Research Letters
Series Number
Index ID 70074653
Record Source USGS Publications Warehouse
USGS Organization Volcano Hazards Program