Revealing the deep structure of the epicentral region of the 2010 Maule, Chile Earthquake (Mw=8.8)
Revealing the deep structure of the epicentral region of the 2010 Maule, Chile Earthquake (Mw=8.8)
复制标题
揭示2010年智利马乌莱地震（Mw=8.8）震中区的深层结构
DOI：
--
复制
发表时间：
2010
期刊：
影响因子：
--
通讯作者：
E. Flueh
中科院分区：
文献类型：
--
作者：
Eduardo Moscoso;I. Grevemeyer;E. Contreras‐Reyes;E. Flueh
2010年2月27日茂勒8.8级地震使纳斯卡-南美板块边界(33°S-38.5°S)破裂约600公里，造成数百人死亡和数十亿美元的结构损失。为了更好地了解这次破坏性地震的同震破裂过程，我们研究了震中区附近纳斯卡-南美俯冲带的地震速度结构。结果表明，该区为楔形体，宽约40公里，典型的沉积速度(<；3.5km/S)解释为由弱而富流体的沉积物组成的活动吸积棱柱。在成像的吸积棱柱的陆地上，速度模型显示了突然的速度对比，表明流变学和岩性的变化被解释为支撑。该支撑点与余震的向海界限重合，确定了大地震的前锋和上倾界限。后者也沿S-S走向(33°S-38.5°S)观察到，那里有1000多次余震向海延伸。
与形变前锋的距离大致相同(约30公里)。另一方面，来自俯冲洋壳顶部的反射将板块边界的位置和倾角限制在10°，从而估计震中位置在22±1公里深。我们的地震结果为评估该地区瞄准浅海海啸地震的能力以及评估地震和海啸危险提供了关键的制约因素。
The 27 February, 2010 Maule earthquake (Mw=8.8) ruptured ~600 km of the Nazca-South America plate boundary (33°S-38.5°S) and caused hundreds of fatalities and billions of dollars in structural losses. In order to better understand the coseismic rupture process of this devastating earthquake, we study the seismic velocity structure of the Nazca-South America subduction zone near the epicentral region. The results show a wedge shaped body ~40 km wide with typical sedimentary velocities (<3.5 km/s) interpreted as an active accretionary prism composed of weak and fluid-rich sediments. Landward of the imaged accretionary prism, the velocity model shows an abrupt velocity-contrast suggesting a rheological and lithological change which is interpreted as a backstop. The backstop is coincident with the seaward limit of the aftershocks, defining the seismic front and up-dip limit of the megathrust earthquake. The latter is also observed along strike (33°S-38.5°S) where the seaward extension of more than 1000 aftershocks is
located at roughly the same distance from the deformation front (~30 km). On the other hand, reflections from the top of the subducting oceanic crust constraint the location of the plate boundary and its dip angle to 10° and thus we estimate the hypocenter location at 22±1 km depth. Our seismic results provide crucial constraints for evaluating the capability of this area to target shallow tsunamigenic earthquakes and assessing earthquake and tsunami hazard.