Abstract
Since the discovery of deep non-volcanic tremor ten years ago the conventional understanding of fault slip behavior is more enigmatic- particularly in subduction zones. Tectonic, or 'non-volcanic', tremor is a low amplitude, low frequency, long duration seismic signal often accompanied with slow slip originating from the plate interface. In this talk, I demonstrate that tectonic tremor from six circum-Pacific subduction zones is comprised of several repeating low frequency earthquakes (LFEs) on the plate interface. The depths of the LFEs are concentrated at the down-dip extent of previous megathrust (M 8+) earthquakes and in some cases exhibit repeating patterns along strike and along dip. In some subduction zones the tremor/LFE activity is episodic. For the Alaska-Aleutian subduction zone, LFEs delimit the down-dip extent of megathrust earthquakes throughout the entire arc suggesting a mechanical relationship between the two phenomena.