Paleoseismology and Paleogeodesy of the Sumatran Subduction Zone

苏门答腊俯冲带的古地震学和古大地测量学

• 批准号: 9804970
• 负责人: Steven Ward
• 金额: $ 3.58万
• 依托单位: University of California-Santa Cruz
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-08-15 至 1999-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9804970&HistoricalAwards=false
• 关键词: Paleoseismology; Paleogeodesy; Sumatran; Subduction; Zone

9804970Ward This research is to complete analysis on coral data gathered earlier between the western coast of Sumatra and the trench of the Sumatran subduction zone, 240 km 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 130 km from the trench and about 25 km above the subduction interface, this project has shown 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 the development of plausible physical models to explain the interseismic and coseismic deformation. This research is a component of the National Earthquake Hazard Reduction Program.

9804970沃德这项研究是为了完成对苏门答腊西海岸和苏门答腊俯冲带海沟（离岸240公里）之间早期收集的珊瑚数据的分析。 这些样本由头珊瑚板组成，记录了与地震发生相关的构造变形引起的海平面变化。 地震复发的性质知之甚少，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和仪器数据的约束不足。 这项工作表明，珊瑚“微环礁”提供了一个无与伦比的机会来测试地震复发的模型，因为它们通过几个大地震周期相当精确地记录了它们的形态和年度条带的垂直变形。 在距离海沟120至130公里、俯冲界面上方约25公里的外弧苏门答腊海岭岛屿上，该项目显示，在1833年的大地震和大约公元1608年和1380年的两次更早的地震期间，突然出现了约2米。 这意味着在这些事件中的每一个期间，俯冲界面上有10到13米的滑动。 也有证据表明，这些岛屿在地震之间的间歇性淹没，其速度从大约4毫米/年增加到大约10毫米/年，这是过去几十年和每次大地震前几十年的平均值。 这笔赠款将支持合理的物理模型的发展，以解释地震间和同震变形。 这项研究是国家地震减灾计划的一个组成部分。