Kinematics and source zone properties of the 2004 Sumatra-Andaman earthquake and tsunami: Nonlinear joint inversion of tide gauge, satellite altimetry, and GPS data
Kinematics and source zone properties of the 2004 Sumatra-Andaman earthquake and tsunami: Nonlinear joint inversion of tide gauge, satellite altimetry, and GPS data
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DOI：
10.1029/2008jb005974
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发表时间：
2010-02-17
影响因子：
3.9
通讯作者：
Melini, D.
中科院分区：
文献类型：
--
作者：
Lorito, S.;Piatanesi, A.;Melini, D.
我们通过对由潮汐计、卫星测高和远场 GPS 记录组成的非均匀数据集进行非线性联合反演，（重新）分析了 2004 年 12 月 26 日苏门答腊-安达曼地震和海啸的来源。目的有两个：(1) 检索主要的运动学破裂参数（滑移、倾角和破裂速度）；(2) 推断源区的刚度。我们独立地估计海啸数据的滑移和大地测量数据的地震矩，以得出刚度。我们的结果证实，2004 年苏门答腊-安达曼地震的震源具有复杂的几何形状，由三个主要滑移带组成，滑移峰值位于震源南部的 30 m 附近。根据沿海沟的汇聚方向，在源头北部，耙向逆时针旋转。源头较深部分的破裂速度高于源头较浅部分的破裂速度，这与预期的刚性随深度增加的情况一致。北部的温度也较低，这与已知的传入板块特性和剪切速度的变化一致。我们的模型的刚度 (20-30 GPa) 低于初步参考地球模型 (PREM) 的发震体积平均值。震源刚度是控制海啸发生的因素之一：对于给定的地震矩，震源刚度越低，引起的海底位移就越大。我们的源模型与之前的研究之间的总体一致性支持了我们联合反演大地测量和海啸数据以进行刚度估计的方法的有效性。
We (re)analyzed the source of the 26 December 2004 Sumatra-Andaman earthquake and tsunami through a nonlinear joint inversion of an inhomogeneous data set made up of tide gauges, satellite altimetry, and far-field GPS recordings. The purpose is twofold: (1) the retrieval of the main kinematics rupture parameters (slip, rake, and rupture velocity) and (2) the inference of the rigidity of the source zone. We independently estimate the slip from tsunami data and the seismic moment from geodetic data to derive the rigidity. Our results confirm that the source of the 2004 Sumatra-Andaman earthquake has a complex geometry, constituted by three main slip patches, with slip peaking at similar to 30 m in the southern part of the source. The rake direction rotates counterclockwise at the northern part of the source, according to the direction of convergence along the trench. The rupture velocity is higher in the deeper than in the shallower part of the source, consistent with the expected increase of rigidity with depth. It is also lower in the northern part, consistent with known variations of the incoming plate properties and shear velocity. Our model features a rigidity (20-30 GPa) that is lower than the preliminary reference Earth model (PREM) average for the seismogenic volume. The source rigidity is one of the factors controlling the tsunami genesis: for a given seismic moment, the lower the rigidity, the higher the induced seafloor displacement. The general consistence between our source model and previous studies supports the effectiveness of our approach to the joint inversion of geodetic and tsunami data for the rigidity estimation.