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Dynamic stresses, Coulomb failure, and remote triggering

Bulletin of the Seismological Society of America

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DOI: 10.1785/0120070049

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Abstract

Dynamic stresses associated with crustal surface waves with 15-30-sec periods and peak amplitudes < 1 MPa are capable of triggering seismicity at sites remote from the generating mainshock under appropriate conditions. Coulomb failure models based on a frictional strength threshold offer one explanation for instances of rapid-onset triggered seismicity that develop during the surface-wave peak dynamic stressing. Evaluation of the triggering potential of surface-wave dynamic stresses acting on critically stressed faults using a Mohr's circle representation together with the Coulomb failure criteria indicates that Love waves should have a higher triggering potential than Rayleigh waves when incident on vertical, strike-slip faults. That (1) the onset of triggered seismicity often appears to begin during the Rayleigh wave rather than the earher-arriving Love wave, (2) vertical strike-slip faults pervade the crust in most tectonic regimes, and (3) Love-wave amplitudes typically exceed those for Rayleigh waves suggests that the explanation for rapid-onset dynamic triggering may not reside solely with a simple static-threshold friction mode. The results also indicate that thrust faults should be more susceptible to dynamic triggering by Rayleigh-wave stresses than normal faults in the shallow seismogenic crust (< 5 km), while the reverse should be true in the lower seismogenic crust (> 5 km). The latter is consistent with the observation that extensional or transtensional tectonic regimes are more susceptible to remote triggering by Rayleigh-wave dynamic stresses than compressional or transpressional regimes. Locally elevated pore pressures may have a role in the observed prevalence of dynamic triggering in extensional regimes and geothermal/volcanic systems.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Dynamic stresses, Coulomb failure, and remote triggering
Series title:
Bulletin of the Seismological Society of America
DOI:
10.1785/0120070049
Volume
98
Issue:
1
Year Published:
2008
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Bulletin of the Seismological Society of America
First page:
66
Last page:
92
Number of Pages:
27