Postseismic relaxation along the San Andreas fault at Parkfield from continuous seismological observations | INSTITUT DE PHYSIQUE DU GLOBE DE PARIS

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  Postseismic relaxation along the San Andreas fault at Parkfield from continuous seismological observations

Type de publication:

Journal Article

Source:

Science, Volume 321, Ticket 5895, p.1478-1481 (2008)

ISBN:

0036-8075

Numéro d'accès:

WOS:000259121800037

Mots-clés:

Sismologie ; N° de contribution : 2393, UMR 7154

Résumé:

Seismic velocity changes and nonvolcanic tremor activity in the Parkfield area in California reveal that large earthquakes induce long- term perturbations of crustal properties in the San Andreas fault zone. The 2003 San Simeon and 2004 Parkfield earthquakes both reduced seismic velocities that were measured from correlations of the ambient seismic noise and induced an increased nonvolcanic tremor activity along the San Andreas fault. After the Parkfield earthquake, velocity reduction and nonvolcanic tremor activity remained elevated for more than 3 years and decayed over time, similarly to afterslip derived from GPS ( Global Positioning System) measurements. These observations suggest that the seismic velocity changes are related to co- seismic damage in the shallow layers and to deep co- seismic stress change and postseismic stress relaxation within the San Andreas fault zone.