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

2004年的安达曼-亚齐地震和海啸使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。本研究项目的目标是通过一项综合古地震学、大地测量学、地质年代学和利用微体化石重建古环境等前沿技术的研究，了解苏门答腊最北部巽他巨型逆冲断层的长期地震行为。这项研究将为北方苏门答腊近海的苏门答腊俯冲带的最北端建立一个俯冲带年表，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调查，这些组成部分有助于确定会聚边缘俯冲带构造的性质。这些组成部分包括俯冲带地震之间的复发间隔、同震和震间垂直地面变化量、主要同震沉降事件的沉降记录、主要同震沉降事件后由巨型逆冲断层上的缓慢下倾后滑引起的抬升记录，以及最后，发展海啸入侵苏门答腊海岸的年表。这项研究的结果将有助于确定沿着北方苏门答腊西海岸沿着的俯冲带地震和海啸的历史，可以追溯到几年前。千年一个跨越至少三个或四个地震周期的俯冲带地震的长期记录将提供对地震和海啸之间平均时间的现实估计，类似于2004年12月袭击北方苏门答腊西海岸的地震和随后发生的海啸。这一项目的成果将在该地区居民中以及与苏丹政府机构一起传播。这些结果将确定，地震和海啸是经常发生的事件，应加以预测，并需要灾害规划。

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.