Depth-varying rupture properties of subduction zone megathrust faults
Depth-varying rupture properties of subduction zone megathrust faults
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DOI：
10.1029/2011jb009133
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发表时间：
2012-04-21
影响因子：
3.9
通讯作者：
Rushing, Teresa M.
中科院分区：
文献类型：
--
作者：
Lay, Thorne;Kanamori, Hiroo;Rushing, Teresa M.
俯冲带板块边界巨型逆冲断裂适应了具有空间变化的滑动行为的相对板块运动。2004年苏门答腊-安达曼(M-W 9.2)、2010年智利(M-W 8.8)和2011年东北(M-W 9.0)大地震在其宽破裂带上的地震波辐射具有相似的深度变化-相干远震短周期辐射优先来自巨型逆冲的较深部分，而最大的断层位移发生在较浅的深度，但产生的相干短周期辐射相对较少。我们用四个不同的断裂域代表了这些和其他深度变化的地震特征，这些断裂域沿着从海沟到孕震带下倾边缘的巨型逆冲延伸。我们将海面以下不到15公里的巨型逆冲部分称为A域，即海啸地震区域。从15公里到35公里深，大地震位移发生在只有适度相干短周期辐射的大范围区域，我们将其命名为B域。较小的孤立巨型逆冲斑块的破裂在C域占主导地位，C域的深度类似于35到55公里。这些孤立的斑块在大破裂和较小的、有时重复的中等大小的事件中都会产生连贯的短周期能量爆发。对于2011年的东北地震，相干远震短周期辐射的地点靠近当地强地面运动的发源地。D域位于俯冲带中，深度30-45公里，相对年轻的大洋岩石圈正被板块浅倾角俯冲，表现为在孕震带以下向稳定滑动或韧性流过渡的地带发生低频地震、地震震动和慢滑事件。
Subduction zone plate boundary megathrust faults accommodate relative plate motions with spatially varying sliding behavior. The 2004 Sumatra-Andaman (M-w 9.2), 2010 Chile (M-w 8.8), and 2011 Tohoku (M-w 9.0) great earthquakes had similar depth variations in seismic wave radiation across their wide rupture zones - coherent teleseismic short-period radiation preferentially emanated from the deeper portion of the megathrusts whereas the largest fault displacements occurred at shallower depths but produced relatively little coherent short-period radiation. We represent these and other depth-varying seismic characteristics with four distinct failure domains extending along the megathrust from the trench to the downdip edge of the seismogenic zone. We designate the portion of the megathrust less than 15 km below the ocean surface as domain A, the region of tsunami earthquakes. From 15 to similar to 35 km deep, large earthquake displacements occur over large-scale regions with only modest coherent short-period radiation, in what we designate as domain B. Rupture of smaller isolated megathrust patches dominate in domain C, which extends from similar to 35 to 55 km deep. These isolated patches produce bursts of coherent short-period energy both in great ruptures and in smaller, sometimes repeating, moderate-size events. For the 2011 Tohoku earthquake, the sites of coherent teleseismic short-period radiation are close to areas where local strong ground motions originated. Domain D, found at depths of 30-45 km in subduction zones where relatively young oceanic lithosphere is being underthrust with shallow plate dip, is represented by the occurrence of low-frequency earthquakes, seismic tremor, and slow slip events in a transition zone to stable sliding or ductile flow below the seismogenic zone.