Effects of three-dimensional crustal structure and smoothing constraint on earthquake slip inversions: Case study of the Mw6.3 2009 L'Aquila earthquake
Effects of three-dimensional crustal structure and smoothing constraint on earthquake slip inversions: Case study of the Mw6.3 2009 L'Aquila earthquake
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DOI：
10.1002/2014jb011650
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发表时间：
2015-01-01
影响因子：
3.9
通讯作者：
Mai, P. Martin
中科院分区：
文献类型：
--
作者：
Gallovic, Frantisek;Imperatori, Walter;Mai, P. Martin
地震滑动反演旨在恢复运动学破裂特征，通常假设一维速度模型和平坦的地球表面。然而，地壳的不均匀性和粗糙地形的存在导致地震散射和其他波传播现象，对地面运动产生复杂的三维影响。在这里，我们研究如何使用不精确的绿色的功能实现包括三维速度扰动和地形影响滑动反演结果。我们创建一套合成地震记录，包括3-D异质地球结构和地形，然后使用绿色的功能计算的水平分层的1-D地球模型反演这些合成。我们应用线性反演，正则化的平滑和积极性约束，并详细研究如何平滑效果扰动的解决方案。除其他外，我们的测试和分辨率分析表明，如何不精确的绿色的功能引入人工滑移率倍数，特别是在浅的深度和峰值滑移率的时间几乎不受所选择的平滑。调查扩展到2009年Mw6.3L'Aquila地震的记录，同时考虑强震和高速率GPS站。我们解释的反演结果考虑到从合成测试中吸取的教训。检索到的滑动模型类似于以前发表的解决方案，使用大地测量数据，显示了一个大的滑动粗糙东南的震源。与其他研究一致，我们发现证据的快速，但亚剪切破裂传播向上倾方向，其次是延迟传播沿着走向。我们推测，破裂部分抑制了深本地化的速度加强补丁，随后经历后滑。
Earthquake slip inversions aiming to retrieve kinematic rupture characteristics typically assume 1-D velocity models and a flat Earth surface. However, heterogeneous nature of the crust and presence of rough topography lead to seismic scattering and other wave propagation phenomena, introducing complex 3-D effects on ground motions. Here we investigate how the use of imprecise Green's functionsachieved by including 3-D velocity perturbations and topographyaffect slip-inversion results. We create sets of synthetic seismograms, including 3-D heterogeneous Earth structure and topography, and then invert these synthetics using Green's functions computed for a horizontally layered 1-D Earth model. We apply a linear inversion, regularized by smoothing and positivity constraint, and examine in detail how smoothing effects perturb the solution. Among others, our tests and resolution analyses demonstrate how imprecise Green's functions introduce artificial slip rate multiples especially at shallow depths and that the timing of the peak slip rate is hardly affected by the chosen smoothing. The investigation is extended to recordings of the 2009 Mw6.3L'Aquila earthquake, considering both strong motion and high-rate GPS stations. We interpret the inversion results taking into account the lessons learned from the synthetic tests. The retrieved slip model resembles previously published solutions using geodetic data, showing a large-slip asperity southeast of the hypocenter. In agreement with other studies, we find evidence for fast but subshear rupture propagation in updip direction, followed by a delayed propagation along strike. We conjecture that rupture was partially inhibited by a deep localized velocity-strengthening patch that subsequently experienced afterslip.