Coseismic and postseismic slip of the 2004 Parkfield earthquake from space-geodetic data
Coseismic and postseismic slip of the 2004 Parkfield earthquake from space-geodetic data
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DOI：
10.1785/0120050818
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发表时间：
2006-09-01
影响因子：
3
通讯作者：
Burgmann, Roland
中科院分区：
文献类型：
--
作者：
Johanson, Ingrid A.;Fielding, Eric J.;Burgmann, Roland
我们将干涉合成孔径雷达 (InSAR) 数据与活动数据和连续全球定位系统 (GPS) 数据联合反演，以了解 2004 年帕克菲尔德地震同震和震后阶段的滑动情况。 InSAR 数据集由八个干涉图组成，这些干涉图取自 Envisat 和 Radarsat 卫星收集的数据，涵盖地震发生期间和震后不同时期的数据。这两个数据集相辅相成，InSAR 提供卫星范围方向上的密集运动采样，而 GPS 提供更稀疏的三维地面运动测量。该模型假设震后滑动呈指数衰减，衰减时间常数为 0.087 年，该常数是根据连续 GPS 和蠕变计数据的时间序列建模确定的。我们发现 1 天同震模型的大地矩震级为 M 6.2，整个震后时期的大地矩震级为 M-W 6.1。同震破裂主要发生在两个滑移凹凸处；一个位于震源附近，另一个位于以北 15-20 公里处。震后滑动发生在断层浅部和两次M 5.0余震的破裂区附近。大地滑移模型与地震矩估计值的比较表明，帕克菲尔德地震的同震矩释放量仅为总量的 25%。这强调了帕克菲尔德路段滑移预算中抗震滑移的重要性。
We invert interferometric synthetic aperture radar (InSAR) data jointly with campaign and continuous global positioning system (GPS) data for slip in the coseismic and postseismic periods of the 2004 Parkfield earthquake. The InSAR dataset consists of eight interferograms from data collected by the Envisat and Radarsat satellites spanning the time of the earthquake and variable amounts of the postseismic period. The two datasets complement each other, with the InSAR providing dense sampling of motion in the range direction of the satellite and the GPS providing more sparse, but three-dimensional measurements of ground motion. The model assumes exponential decay of the postseismic slip with a decay time constant of 0.087 years, determined from time series modeling of continuous GPS and creepmeter data. We find a geodetic moment magnitude of M 6.2 for a 1-day coseismic model and M-W 6.1 for the entire postseismic period. The coseismic rupture occurred mainly in two slip asperities; one near the hypocenter and the other 15-20 km north. Postseismic slip occurred on the shallow portions of the fault and near the rupture areas-of two M 5.0 aftershocks. A comparison of the geodetic slip models with seismic moment estimates suggests that the coseismic moment release of the Parkfield earthquake is as little as 25% of the total. This underlines the importance of aseismic slip in the slip budget for the Parkfield segment.