Postseismic relaxation along the San Andreas fault at Parkfield from continuous seismological observations
Postseismic relaxation along the San Andreas fault at Parkfield from continuous seismological observations
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DOI：
10.1126/science.1160943
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发表时间：
2008-09-12
期刊：
影响因子：
56.9
通讯作者：
Larose, E.
中科院分区：
文献类型：
--
作者：
Brenguier, F.;Campillo, M.;Larose, E.
加州帕克菲尔德地区的地震速度变化和非火山震颤活动揭示了大地震会诱发圣安德烈亚斯断层带地壳性质的长期扰动。2003年的圣西蒙和2004年的帕克菲尔德地震都降低了地震速度，从周围的地震噪声的相关性测量，并引起了增加的非火山震颤活动沿着圣安德烈亚斯断层。在帕克菲尔德地震后，速度降低和非火山性震颤活动持续升高超过3年，并随着时间的推移而衰减，类似于来自GPS（全球定位系统）测量的余震。这些观测结果表明，地震速度变化与浅部同震破坏有关，与圣安德烈亚斯断裂带内部深部同震应力变化和震后应力松弛有关。
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.