A 15-year catalog of more than 1 million low-frequency earthquakes: tracking tremor and slip along the deep San Andreas Fault

David R. Shelly

Published August 14, 2017, SCEC Contribution #7653, 2017 SCEC Annual Meeting Poster #078

Low-frequency earthquakes (LFEs) are small, rapidly recurring slip events that occur on the deep extensions of some major faults. Their collective activation is often observed as a semi-continuous signal known as tectonic (or non-volcanic) tremor. This poster presents a catalog of more than 1 million LFEs detected along the central San Andreas Fault from 2001-2016. These events have been detected via a multi-channel matched-filter search, cross-correlating waveform templates representing 88 different LFE families with continuous seismic data. Together, these source locations span nearly 150 km along the central San Andreas Fault, ranging in depth from ~16-30 km.

This accumulating catalog has been the source for numerous studies examining the behavior of these LFE sources and the inferred slip behavior of the deep fault. The relatively high temporal and spatial resolution of the catalog has provided new insights into properties such as tremor migration, recurrence, and triggering by static and dynamic stress perturbations. Collectively, these characteristics are inferred to reflect a very weak fault likely under near-lithostatic fluid pressure, yet the physical processes controlling the stuttering rupture observed as tremor and LFE signals remain poorly understood. The catalog itself has now been published (electronic supplement of Shelly [2017]), with the goal of providing a useful resource for continued future investigations.

Reference:
Shelly, D. R. (2017). A 15 year catalog of more than 1 million low‐frequency earthquakes: Tracking tremor and slip along the deep San Andreas Fault. Journal of Geophysical Research: Solid Earth, 122(5), 3739-3753.

Key Words
tectonic tremor, low-frequency earthquakes, slow slip, Parkfield

Citation
Shelly, D. R. (2017, 08). A 15-year catalog of more than 1 million low-frequency earthquakes: tracking tremor and slip along the deep San Andreas Fault. Poster Presentation at 2017 SCEC Annual Meeting.

Related Projects & Working Groups
Seismology