Paleoseismology and Paleogeodesy of the Sumatran Subduction Zone

9804732 sieh这项研究是为了完成对早先在苏门答腊西海岸和苏门答腊俯冲带海沟之间收集的珊瑚数据的分析，离岸240公里。这些样本由头珊瑚板块组成，记录了与地震发生有关的构造变形引起的海平面变化。人们对地震复发的性质了解甚少，这在很大程度上是因为物理模型受到稀疏的古地震和古大地测量记录以及仪器数据的限制。这项工作表明，珊瑚“微环礁”为测试地震复发模型提供了无与伦比的机会，因为它们在形态和年带状上相当精确地记录了几次大地震周期的垂直变形。在距离海沟120至130公里、距俯冲界面约25公里的外弧苏门答腊脊的岛屿上，该项目揭示了在1833年的大地震期间，以及在公元1608年和1380年的两次更早的地震中，突然出现了大约2米的高度。这意味着在这些事件中，每次俯冲界面都有10到13米的滑动。还有证据表明，在过去几十年和每次大地震前的几十年里，这些岛屿的地震间淹没速度从每年约4毫米增加到每年约10毫米。这笔拨款将支持进一步记录和扩展这些结果。这项研究是国家减少地震危害计划的一个组成部分。

9804732SiehThis research is to complete analysis on coral data gathered earlier between the western coast of Sumatra and the trench of the Sumatran subduction zone, 240km offshore. The samples consist of slabs of head corals that record sea-level changes caused by tectonic deformation related to earthquake occurrence. The nature of earthquake recurrence is poorly understood, in large part because physical models are constrained inadequately by sparse paleoseismic and paleogeodetic records and by instrumental data. This work has shown that coral "microatolls" offer an unrivalled opportunity to test models of earthquake recurrence, because they record vertical deformation through several large-earthquake cycles quite precisely in their morphology and annual banding. On the islands of the outer-arc Sumatran ridge, 120 to 130km from the trench and about 25km above the subduction interface, this project has revealed a sudden emergence of about 2 meters during the giant earthquake of 1833 and during two earlier events about AD 1608 and 1380. This implies 10 to 13 meters of slip on the subduction interface during each of these events. There is also evidence of episodic, interseismic submergence of the islands at rates that increase trenchward from about 4 to about 10 mm/yr, averaged over the past several decades and in the decades prior to each large earthquake. This grant will support further documentation and extension of these results. This research is a component of the National Earthquake Hazard Reduction Program.