Slip distribution of the 2005 Nias earthquake (Mw 8.6) inferred from geodetic and far-field tsunami data
Slip distribution of the 2005 Nias earthquake (Mw 8.6) inferred from geodetic and far-field tsunami data
复制标题
根据大地测量和远场海啸数据推断的 2005 年尼亚斯地震（Mw 8.6）的滑动分布
DOI：
10.1093/gji/ggaa384
复制
发表时间：
2020
影响因子：
2.8
通讯作者：
Ho Tung-Cheng
中科院分区：
文献类型：
--
作者：
Fujii Yushiro;Satake Kenji;Watada Shingo;Ho Tung-Cheng
通过对2005年尼亚斯地震（Mw8.6）断层的GPS、海岸升降资料和海啸波形资料的反演，估计了该地震断层的滑动分布。2005年尼亚斯地震发生在2004年苏门答腊-安达曼地震（Mw9.1）之后大约三个月，位于印度尼西亚苏门答腊岛的南部延伸部分。2005年地震引发的海啸造成的损失远低于2004年海啸，但印度洋周围包括非洲和南极洲海岸的验潮仪和洋底压力计记录到了这一情况。固体地球和海洋之间的弹性和重力耦合不仅会导致旅行时间延迟，而且会导致远场海啸波形相对于长波理论预测的变化。在海啸波形反演中，我们对计算的海啸绿色函数进行了弹性和重力耦合效应的修正。在断层深部（20-54 km）发现了一个扩散性滑移（400 km × 100 km范围内约2 m），在震中偏南处发现了一个较大的局部性滑移（100 km × 100 km范围内约7 m）。断层较深处的大滑动是产生小海啸的原因。使用远场海啸数据反演得到的滑动分布类似于单独使用当地大地测量数据和当地大地测量和远场海啸数据联合反演得到的滑动分布，这也类似于以前基于当地大地测量数据的研究中得到的滑动分布。这表明，远场海啸波形，一旦传播效应校正，可用于估计滑动分布的大型海底地震导致的结果是类似于那些使用稀疏的本地大地测量数据。
We estimated the slip distribution on the fault of the 2005 Nias earthquake (Mw8.6) by inversions of local GPS and coastal uplift/subsidence data and tsunami waveform data. The 2005 Nias earthquake occurred approximately three months after the 2004 Sumatra–Andaman earthquake (Mw9.1) at the southern extension off Sumatra Island, Indonesia. The tsunami from the 2005 earthquake caused significantly less damage than the 2004 tsunami, yet was recorded at tide gauges and ocean bottom pressure gauges around the Indian Ocean, including the coasts of Africa and Antarctica. The elastic and gravitational coupling between the solid earth and the ocean causes not only a traveltime delay but also the change of waveforms of far-field tsunamis relative to the prediction based on the long-wave theory. We corrected the computed tsunami Green's functions for the elastic and gravitational coupling effect in the tsunami waveform inversion. We found a diffused slip (∼2 m over an area of 400 km × 100 km) at deeper parts (20–54 km) of the fault with a large localized slip (7 m over 100 km × 100 km) slightly south of the epicentre. The large slips at deeper parts of the fault were responsible for the small tsunami generation. Inversion using far-field tsunami data yielded a slip distribution similar to that obtained using local geodetic data alone and that from the joint inversion of local geodetic and far-field tsunami data, which is also similar to slip distributions from previous studies based on local geodetic data. This demonstrates that far-field tsunami waveforms, once corrected for propagation effects, can be used to estimate the slip distribution of large submarine earthquakes leading to results that are similar to those obtained using sparse local geodetic data.