High-frequency seismic radiation from Maule earthquake (Mw 8.8, 2010 February 27) inferred from high-resolution backprojection analysis
High-frequency seismic radiation from Maule earthquake (Mw 8.8, 2010 February 27) inferred from high-resolution backprojection analysis
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DOI：
10.1093/gji/ggu311
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发表时间：
2014-11
影响因子：
2.8
通讯作者：
M. Palo;F. Tilmann;F. Krüger;Lutz Ehlert;D. Lange
中科院分区：
文献类型：
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作者：
M. Palo;F. Tilmann;F. Krüger;Lutz Ehlert;D. Lange
马乌莱地震（2010年2月27日，Mw8.8，智利）打破了俯冲巨型逆冲断层沿着先前锁定的部分。根据国际余震部署，已经可以获得精确定位的余震目录。使用23个位置良好的余震，我们校准经典的地震反射反投影程序，以映射地震期间发出的高频地震辐射。该校准校正标准地球模型中的走时，该走时具有特定于每个站的静态项和特定于网格点和站的每个组合的“动态”项。第二项已通过克里格法在整个滑动区域内插值，并且比静态项小大约一个数量级。这一程序确保了破裂发展的地震图像相对于当地网络记录的余震正确定位，并且不依赖于主震的准确震源位置。我们跟踪了一个持续了160 s的双侧破裂传播，其主要分支以约3 km s-1的速度向东北方向破裂。最大能量发射的区域与最大同震滑动相抵消，但与大多数板块界面余震发生的区域相匹配。沿着倾向，能量优先从两个不相连的界面带释放，并且从开始约20 s后可以看到从较浅的带到较深的带的明显跳跃。然而，这两条带都保持活动，直到破裂结束。这些带大致匹配的接口余震，这是分裂成两个集群的事件在不同的深度，从而表明存在一个反复的过渡，从粘滑蠕动摩擦制度的位置。
The Maule earthquake (2010 February 27, Mw 8.8, Chile) broke the subduction megathrust along a previously locked segment. Based on an international aftershock deployment, catalogues of precisely located aftershocks have become available. Using 23 well-located aftershocks, we calibrate the classic teleseismic backprojection procedure to map the high-frequency seismic radiation emitted during the earthquake. The calibration corrects traveltimes in a standard earth model both with a static term specific to each station, and a ‘dynamic’ term specific to each combination of grid point and station. The second term has been interpolated over the whole slipping area by kriging, and is about an order of magnitude smaller than the static term. This procedure ensures that the teleseismic images of rupture development are properly located with respect to aftershocks recorded with local networks and does not depend on accurate hypocentre location of the main shock. We track a bilateral rupture propagation lasting ∼160 s, with its dominant branch rupturing northeastwards at about 3 km s−1. The area of maximum energy emission is offset from the maximum coseismic slip but matches the zone where most plate interface aftershocks occur. Along dip, energy is preferentially released from two disconnected interface belts, and a distinct jump from the shallower belt to the deeper one is visible after about 20 s from the onset. However, both belts keep on being active until the end of the rupture. These belts approximately match the position of the interface aftershocks, which are split into two clusters of events at different depths, thus suggesting the existence of a repeated transition from stick-slip to creeping frictional regime.