Collaborative Research: A Paleoseismic Record of Repeated Great Earthquakes on the Sunda Subduction Megathrust, Northern Sumatra

2004年的安达曼-亚齐地震和海啸将全球的注意力集中在苏门答腊俯冲带的最北端，并对苏门答腊最北端近海的巽他巨型逆冲断层的过去地质历史提出了疑问。本研究项目的目的是通过整合古地震学、大地测量学、地质年代学和利用微化石重建古环境的前沿技术，了解苏门答腊岛最北端巽他巨型逆冲断层的长期地震行为。这项研究将为苏门答腊北部近海的苏门答腊俯冲带最北端的过去建立一个俯冲带年代学，可以追溯到大约5000年前。重建的俯冲带历史将包括对几个关键组成部分的研究，这些组成部分有助于确定汇聚边缘俯冲带构造的性质。这些成分包括俯冲带地震之间的重复间隔，同震和地震间垂直地面变化的数量，主要同震沉降事件前的沉降记录，主要同震沉降事件后的隆升记录，主要同震沉降事件是由大型逆冲断层缓慢的下倾余震引起的，最后是海啸侵入苏门答腊海岸的年表。这项研究的结果将有助于确定几千年前苏门答腊岛北部西海岸的俯冲带地震和海啸的历史。对至少跨越三到四个地震周期的俯冲带地震的长期记录将为地震和海啸之间的平均时间提供现实的估计，类似于2004年12月袭击苏门答腊岛北部西海岸的地震和随之而来的海啸。该项目的结果将在该地区的居民和苏门答腊政府机构之间传播。这些结果将证明，地震和海啸是经常发生的事件，应该加以预测，需要进行灾害规划。

The 2004 Andaman-Aceh earthquake and tsunami focused global attention on the northernmost part of the Sumatran subduction zone and raised questions about the past geologic history of the Sunda megasthrust offshore of northernmost Sumatra. The objective of this research project is to understand the long-term seismic behavior of the Sunda megathrust of northernmost Sumatra through a study that integrates forefront techniques of paleoseismology, geodesy, geochronology and paleo-environmental reconstruction using microfossils. The study will establish a subduction zone chronology for the northernmost past of the Sumatran subduction zone offshore of northern Sumatra going back approximately five thousand years. The reconstructed subduction zone history will include investigation of several critical components that help define the nature of subduction zone tectonics at convergent margins. These components include recurrence interval between subduction zone earthquakes, amounts of coseismic and interseismic vertical land level changes, documentation of subsidence precursory to the main coseismic subsidence event, documentation of uplift after the main coseismic subsidence event caused by slow, down dip afterslip on the megathrust and finally, development of a chronology of tsunami that invades the Sumatran coast.Results of this research will help define the history of subduction zone earthquakes and tsunami along the west coast of northern Sumatra going back several thousand years. A long-term record of subduction zone earthquakes that spans at least three or four earthquake cycles will provide realistic estimates of the average time between earthquakes and tsunamis similar to the earthquake and ensuing tsunami that struck the west coast of northern Sumatra in December 2004. Results from this project will be disseminated among the inhabitants of the region and with Sumatran governmental agencies. These results will establish that earthquake and tsunami are recurrent events that should be anticipated and that require disaster planning.