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首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >Contribution of radar interferometry to a two-step inversion of the kinematic process of the 1992 Landers earthquake
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Contribution of radar interferometry to a two-step inversion of the kinematic process of the 1992 Landers earthquake

机译：雷达干涉测量法对1992年Landers地震运动过程的两步反演的贡献

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摘要

We study the rupture process of the 1992 Landers earthquake. To limit the trade-off between slip amplitude and rupture time that affects solutions using only seismological data, we adopt a two-step approach. We first constrain the slip distribution and its uncertainty by independent geodetic data to recover in the second step the temporal details of the rupture propagation. The first step consists of an inversion of interferometric data and Global Positioning System measurements, both independently and together, to constrain slip distribution on a three-segment fault model along both strike and dip direction. We use a genetic algorithm to test the uniqueness of the solution and a least squares formulation to find the model which best fits the data. We conclude from the results of these geodetic inversions that interferometric data are rich enough to access the slip distribution in the case of the Landers earthquake. Since the surface deformations are more sensitive to shallow slip in our configuration, the slip amplitude is better resolved near the surface than at depth. The resulting slip distribution is in agreement with geological observations at the surface and confirms the heterogeneous nature of the Landers earthquake. Most of the slip occurs at shallow depths, on the Homestead Valley fault )second segment), with a maximum value of around 7 m. Another high slip zone is observed on the Johnson Valley fault (first segment) at 8 km depth. In the second step, we invert strong motion data with the a priori final slip amplitude and its uncertainty deduced from geodetic data to constrain the time history of the rupture process. This second step emphasizes a strong variation of the temporal development of the earthquake. Fast rupture front velocities appear within high slip zones, and the rupture slows when it encounters a resistance along the fault. On average, the rupture front propagates with velocities close to the S wave velocity and terminates about 20 s after initiation. The large variations in both slip amplitude and rupture velocity suggest that the rupture process is better described by successively breaking asperities than by a pulse propagating with constant velocity.
机译：我们研究了1992年Landers地震的破裂过程。为了限制仅影响地震数据的滑移振幅和破裂时间之间的权衡影响解决方案，我们采用了两步法。我们首先通过独立的大地测量数据来约束滑动分布及其不确定性，以便在第二步中恢复破裂传播的时间细节。第一步包括干涉数据的反演和全球定位系统的测量结果，无论是独立的还是一起的，以限制在三段断层模型上沿走向和俯冲方向的滑动分布。我们使用遗传算法来测试解决方案的唯一性，并使用最小二乘方公式来找到最适合数据的模型。从这些大地反演的结果可以得出结论，在Landers地震的情况下，干涉数据足够丰富，可以访问滑动分布。由于在我们的配置中，表面变形对浅层滑动更敏感，因此在表面附近的滑动幅度比在深度处的滑动幅度更好。所产生的滑移分布与表层的地质观测结果一致，证实了Landers地震的非均质性。大部分滑移发生在霍姆斯特德谷断层的第二段浅层深度，最大值约为7 m。在Johnson Valley断层（第一段）的8 km深度处观察到另一个高滑动带。在第二步中，我们用先验的最终滑动幅度和大地测量数据推导出的不确定性来反演强运动数据，以约束破裂过程的时间历程。第二步强调地震时间发展的强烈变化。在高滑动区域内出现快速破裂的前速度，并且当破裂沿断层遇到阻力时破裂速度变慢。平均而言，破裂前缘以接近S波速度的速度传播，并在引发后约20 s终止。滑动幅度和破裂速度的较大变化表明，与连续以恒定速度传播的脉冲相比，通过连续破裂粗糙来更好地描述破裂过程。

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