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Slow Slip Events: Earthquakes in Slow Motion

Jean-Philippe Avouac, Sylvain G. Michel, & Adriano Gualandi

Published August 15, 2018, SCEC Contribution #8804, 2018 SCEC Annual Meeting Poster #118

Faults can slip episodically during earthquakes, but also during transient aseismic slip events, commonly called Slow Slip Events (SSEs). The mechanisms at the origin of SSEs might be investigated based on their scaling properties. Previous compilation of SSE characteristics from various area suggested their moment, M0, is proportional to their duration, T, suggesting a different physics from regular earthquakes which obey M_0∝T^3. Thanks to a new catalog of SSEs on the Cascadia megathrust consisting of 65 events between 2008 and 2018, we find that SSEs actually follow the same scaling laws as regular earthquakes: M_0∝T^3, M_0∝A^(3/2), where A is the rupture area, , and the Gutenberg-Richter frequency-magnitude relationship, with a b-value of ~0.8. These scaling properties are to expected if slow slip events, like regular earthquakes, are frictional instabilities on faults embedded in a elastic medium, though with much lower stress drop that we estimated to ~1 kPa. SSE might therefore be considered as earthquakes in slow motion.

Key Words
Slow Slip Events, Earthquakes

Avouac, J., Michel, S. G., & Gualandi, A. (2018, 08). Slow Slip Events: Earthquakes in Slow Motion. Poster Presentation at 2018 SCEC Annual Meeting.

Related Projects & Working Groups
Tectonic Geodesy