Tectonic Tremor Triggered along Major Strike-Slip Faults around the World
Abstract
Over the last decade, deep tectonic tremor has been observed at several major plate-bounding faults around the Pacific Rim. Observations in these regions show that ambient tremor occurs spontaneously in association with geodetically detectable slow-slip events and that triggered tremor occurs in response to small stress perturbations arising from solid earth tides as well as passing seismic waves of a distant earthquake. Tremor generally occurs in the lower crust, beneath the seismogenic zone where earthquakes occur. In order to investigate the potential link between tremor and earthquake nucleation, further study of when, where, and how tremor occurs is needed. Here, we present a review of remotely triggered tectonic tremor in four strike-slip regions: (1) the Queen Charlotte Fault near Haida Gwaii, Canada, (2) the Eastern Denali Fault in Yukon, Canada, (3) the Enriquillo-Plantain Garden Fault in the southern Haiti peninsula, and (4) the Parkfield-Cholame segment of the San Andreas Fault near Parkfield, California. In Haida Gwaii, Yukon and Parkfield, we first compute the estimated dynamic stress for all magnitude ≥ 5.5 earthquakes based on the magnitude listed in the Advanced National Seismograph System (ANSS) earthquake catalog and epicentral distance to the region where tremor is observed. We then retrieve seismic data from local networks for earthquakes that are estimated to generate ≥ 1 kPa dynamic stress, without regard to epicentral distance. We characterize tremor triggered by these distant earthquakes as broadband signals with long duration that are coincident with surface waves from a distant event or occur in a large cluster immediately following the teleseismic wavetrain. In Haiti, a temporary seismic network was deployed shortly after the 2010/01/12 Mw7.0 Haiti earthquake. Thus, we are only able to report on triggering by the 2010/02/27 Mw8.8 Maule, Chile earthquake that occurred shortly thereafter. In Parkfield, we use a low-frequency earthquake based tremor catalog for locations. In other regions, we locate the tremor sources using the envelope cross-correlation method if the triggered tremor is visible on more than two recording stations. In general, tremor in all of these regions can be triggered by both Love and Rayleigh waves, and the triggering behavior is in agreement with the Coulomb failure criterion for surface waves incident on strike-slip faults. Furthermore, we provide a comparison of dynamic stress triggering potential as well as frequency dependent triggering in these regions. Lastly, we compare the waveform characteristics of the triggered tremor observed on these strike-slip faults, such as frequency content, seismic moment, and stress drop.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFM.S51B2362A
- Keywords:
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- 7250 SEISMOLOGY Transform faults