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首页> 外文期刊>Geophysical Research Letters >Geodetic imaging of coseismic slip and postseismic afterslip: Sparsity promoting methods applied to the great Tohoku earthquake
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Geodetic imaging of coseismic slip and postseismic afterslip: Sparsity promoting methods applied to the great Tohoku earthquake

机译：同震滑动和地震后滑的大地成像：稀疏性促进方法在东北大地震中的应用

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摘要

Geodetic observations of surface displacements during and following earthquakes such as the March 11, 2011 great Tohoku earthquake can be used to constrain the spatial extent of coseismic slip and postseismic afterslip, and characterize the spectrum of earthquake cycle behaviors. Slip models are often regularized by assuming that slip on the fault varies smoothly in space, which may result in the artificial smearing of fault slip beyond physical boundaries. Alternatively, it may be desirable to estimate a slip distribution that is spatially compact and varies sharply. Here we show that sparsity promoting state vector regularization methods can be used to recover slip distributions with sharp boundaries, representing an alternative end-member result to very smooth slip distributions. Using onshore GPS observations at 298 stations during and in the ～ 2 weeks following the Tohoku earthquake, we estimate a band of coseismic slip between 30 and 50 km depth extending 500 km along strike with a maximum slip of 64 m, corresponding to a minimum magnitude estimate of M _W = 8.8. Our estimate of afterslip is located almost exclusively down-dip of the coseismic rupture, with a transition between 40 and 50 km depth and an equivalent moment magnitude M _W = 8.2. This depth may be interpreted as coincident with the transition from velocity strengthening to velocity weakening frictional behavior, consistent with the upper limit of cold subduction estimates of the thermal structure of the Japan trench.
机译：在2011年3月11日东北地震等地震期间和地震之后的地面位移的大地测量观测可以用来限制同震滑移和后震后滑的空间范围，并表征地震周期行为的频谱。滑动模型通常通过假设断层上的滑动在空间上平滑变化来进行正则化，这可能导致断层的人为涂抹超出物理边界。替代地，可能期望估计在空间上紧凑并且急剧变化的滑动分布。在这里，我们表明稀疏性促进状态向量正则化方法可用于恢复具有锐利边界的滑移分布，代表了非常平滑的滑移分布的替代最终成员结果。在东北地震发生期间和前后2周内，利用298个站点的陆上GPS观测值，我们估算了30至50 km深度的同震滑移带，沿地震波沿500 km延伸，最大滑移为64 m，对应于最小震级M _W的估计值= 8.8。我们对后滑的估计几乎完全位于同震破裂的下倾角，深度在40至50 km之间过渡，等效矩量级M _W = 8.2。该深度可以解释为与从速度增强到速度减弱的摩擦行为的过渡相一致，与日本海沟热结构冷俯冲估计的上限一致。

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