Automated detection and location of Cascadia tremor

A new autonomous seismic location and detection methodology enables real-time opportunities for high-resolution spatio-temporal monitoring of non-volcanic tremor. Combining a unique cross-correlation technique with epicenter clustering analysis in northern Cascadia automatically yields thousands of tremor epicenters from the May 2008 Episodic Tremor and Slip ( ETS) event while routinely detecting and locating inconspicuous inter-ETS tremor bursts. Although ETS events in this area produce about two weeks of continuous tremor, we find a nearly equal amount of tremor during the last 15-month inter-ETS period. The resulting ETS and inter-ETS epicenters occur in the slow slip region where the plate interface is 30-45 km deep and have a sharp, well-resolved updip boundary about 75 km east of the downdip edge of the seismogenic megathrust zone. This ability to track tremor with high spatio-temporal resolution facilitates automatic tremor monitoring and the mapping of the transition zone and regions of locked zone stress accumulation. Citation: Wech, A. G., and K. C. Creager ( 2008), Automated detection and location of Cascadia tremor, Geophys. Res. Lett., 35, L20302, doi: 10.1029/2008GL035458.