Megathrust seismic hazards by reflection mapping

世界上大部分地区？美国的大地震是与俯冲构造过程有关的浅层事件。破坏和生命损失不仅来自地震本身，也来自它们通常产生的海啸。在美国，阿拉斯加和卡斯卡迪亚（从加利福尼亚北部延伸到加拿大南部的沿海地区）在未来的某个时候肯定会经历这样的事件。估计这些地震可能引起的地面运动显然是一件相当重要的事情。这样的估计取决于产生大地震的俯冲逆冲断层的宽度。孕震带；这个区域的陆地边缘越靠近海岸，地面运动可能越长越强。深反射地震方法可以提供一种定位发震带下倾极限的方法。该项目将通过在阿拉斯加-阿留申俯冲带的大部分地区获取海洋多通道（MCS）和广角反射数据来测试该方法。然后，可以将反射填图结果与现有地震余震和大地测量资料确定的地震破裂界限进行比较。

Most of the world?s great earthquakes are shallow events that occur in association with the tectonic process of subduction. Damage and loss of life result not only from the earthquakes themselves, but from the tsunamis they commonly spawn as well. Regions in the U.S. that will certainly experience such events at some time in the future are Alaska and Cascadia (the coastal region extending from northern California to southern Canada). Estimating the ground motions that can be expected from these earthquakes is obviously a matter of considerable importance. Such estimates depend on the width of the subduction megathrust that produces great earthquakes ? the seismogenic zone; the nearer the landward edge of this zone is to the coast, the longer and stronger the ground motion is likely to be. Deep reflection seismic methods may provide a means of locating the downdip limit of the seismogenic zone. This project will test this method by acquiring marine multichannel (MCS) and wide angle reflection data over a large portion of the Alaska-Aleutian subduction zone. The reflection mapping results can then be compared with the earthquake rupture limit defined by existing earthquake aftershock and geodetic data.