Slip model of the 2008 Mw 7.9 Wenchuan (China) earthquake derived from co-seismic GPS data
Slip model of the 2008 Mw 7.9 Wenchuan (China) earthquake derived from co-seismic GPS data
复制标题
DOI：
10.5047/eps.2009.05.003
复制
发表时间：
2010-11
期刊：
影响因子：
--
通讯作者：
F. Diao;X. Xiong;Rongjiang Wang;Yong Zheng;H. Hsu
中科院分区：
文献类型：
--
作者：
F. Diao;X. Xiong;Rongjiang Wang;Yong Zheng;H. Hsu
利用近场同震GPS数据推导了2008年5月12日汶川地震的滑动分布。基于野外测量和地质观测，此次地震表现为北川断裂以及彭县至灌县附近一条断裂的破裂，两条断裂均随深度增加倾角变小。利用分层弹性地壳模型，我们得到了一个滑动模型，该模型不仅与同震GPS数据拟合最佳，而且与野外调查所观测到的地表破裂大体一致。滑动最大值在北川和江油附近很浅的深度占主导地位，尽管由于近断层区域数据覆盖不均匀，滑动分布的确切峰值没有得到很好的约束。因此，我们反演中的最大滑动量限定在约9米，这是根据野外测量估计的，但对滑动方向（即滑动角）没有严格限制。该滑动模型得出的矩震级非常接近Mw = 7.9，这是基于远震观测的估计值。在震源附近，滑动呈现逆冲性质。北川附近的主要破裂包含右旋走滑和逆冲分量。次生断裂上的滑动以逆冲分量为主，最大值约为2 - 3米。
Near-field co-seismic GPS data were used to derive the slip distribution of the 12 May 2008 Wenchuan earthquake. Based on field measurements and geological observations, the earthquake is represented by ruptures on the Beichuan fault and a neighboring fault from Pengxian to Guanxian, both dipping with a decreasing angle with depth. Using a layered elastic crust model, we obtained a slip model that not only best fits the co-seismic GPS data but which also shows general consistency with the surface ruptures observed from the field survey. The slip maxima are dominant at a very shallow depth near Beichuan and Jiangyou, although the exact peak value of the slip distribution is not well constrained due to the inhomogeneous data coverage in the near-fault area. The maximum slip in our inversion is thus limited to about 9 m, as estimated from the field measurement, but no strict restriction is applied to the slip direction, i.e., the rake angle. The slip model yields a moment magnitude that is very close to Mw = 7.9, which is the estimate based on teleseismic observations. Near the hypocenter, the slip exhibits reverse behavior. The major rupture near Beichuan involves both right-lateral strike-slip and reverse components. Slip on the secondary fault is dominated by the reverse component with a maximum of approximately 2–3 m.