Evaluation of Historical Earthquake Interaction and Seismic Risk to Western Sumatra

西苏门答腊岛历史地震相互作用和地震风险评估

• 批准号: NE/F01161X/1
• 负责人: John McCloskey
• 金额: $ 6.47万
• 依托单位: University of Ulster
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2008
• 资助国家: 英国
• 起止时间: 2008 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FF01161X%2F1
• 关键词: Evaluation; Historical; Earthquake; Interaction; Seismic

On 26 December 2004 the great Sumatra Andaman Earthquake ruptured the Sunda megathrust for a length of more than 1200km resulting in a magnitude 9.3 earthquake and a massive tsunami which devastated the entire circum-Indian ocean coastline. Over 250000 people died. Earthquakes do not occur in isolation but one earthquake deforms the earth's crust around it and transfers stress onto other structures which may also generate other, so called triggered earthquakes. Over the last ten years or so, scientists have tried to understand this effect and have developed mathematical tools for the calculation of these interaction stresses in the crust. This work has lead to the idea that if the interaction stresses could be calculated immediately after an earthquake, the structures which would be likely to produce other events might be identified, thus locating areas of particularly high seismic hazard. Following the Sumatra-Andaman earthquake, the University of Ulster geophysics research group illustrated the usefulness of this method by pointing out the increase risk of another great (ie M>8) earthquake under the Islands of Simeulue and Nias to the west of Sumatra. The forecast event occurred (M8.7) 11 days after their paper was published in Nature While this work clearly illustrated the power of the technique there is, unfortunately not one-to-one mapping between the calculated stresses and the following earthquakes. So, while we can say where another earthquake is likely we cannot say when, or even how likely. It is of great importance that more work is done if we are to be able confidently and consistently to use the interaction stress technique in a practical way. Another crucial and closely linked question is: what earthquake are we trying to forecast? While some scientists believe that big earthquakes recur with more or less the same magnitude in more or less the same place, others point out significant failures in this idea. Big earthquakes sometimes overlap, occur in different places, combine into even bigger earthquakes or break more than one fault. In this project, the team, which brings together scientists from the universities of Ulster and Edinburgh as well as from the National Institute for Geophysics and Vulcanology in Rome, will examine how good the interaction stress idea is, not by looking into the future, but by looking into the past. Due to the concerted effort of scientists for over 20 years, there are few places on earth for which we have a better picture of past big (M>8) earthquake activity. We are confident that we know the locations and approximate sizes of all earthquakes (M>6) which have occurred there since about 1600. We also know a lot about plate convergence - the driving force for earthquake generation. In this project we will put this information together in a complex numerical simulation to reconstruct the entire stress field in the western Sumatran region for the last 400 years. The resulting 3D stress history will allow us to see if the interaction stress idea could have been used to explain the last 400 years of earthquakes; this will help us to understand what is likely to happen next. In addition we will look at the recent records of smaller earthquakes and see if we can use these to tell us about the dependability of the simple recurrence behaviour for the big ones. This problem is complex and requires very careful application of statistical techniques to be sure we reach the right conclusions. We will develop many of these during the project. Western Sumatra is currently one of highest earthquake risk areas in the world. Coastal populations around the Indian ocean, and on the western coast of Sumatra in particular live with the threat of another great earthquake which has the potential to kill on the same scale as the boxing day event. This project will not stop the earthquake but it will contribute to a body of scientific knowledge which will ultimately help to prepare people for it.

2004年12月26日，苏门答腊安达曼大地震使巽他巨型逆冲断层断裂，长度超过1200公里，引发9.3级地震和大规模海啸，摧毁了整个环印度洋海岸线。超过25万人死亡。地震不是孤立发生的，而是一次地震使它周围的地壳变形，并将应力转移到其他结构上，这些结构也可能产生其他所谓的触发地震。在过去十年左右的时间里，科学家们试图理解这种影响，并开发了计算地壳中这些相互作用应力的数学工具。这项工作产生了这样一种想法，即如果在地震发生后立即计算出相互作用应力，那么可能产生其他事件的结构就可能被识别出来，从而确定地震危险性特别高的区域。在苏门答腊-安达曼地震之后，阿尔斯特大学地球物理研究小组指出，苏门答腊以西的西穆鲁和尼亚斯群岛下发生另一场大地震的风险增加，从而说明了这种方法的实用性。预测事件发生在他们的论文发表在《自然》杂志11天后（M8.7），虽然这项工作清楚地说明了这项技术的力量，但不幸的是，计算出的应力与随后发生的地震之间没有一对一的映射。所以，虽然我们能说哪里有可能发生另一次地震，但我们不能说什么时候，甚至有多大可能。如果我们能够自信地、持续地以一种实际的方式使用交互压力技术，那么做更多的工作是非常重要的。另一个关键且密切相关的问题是：我们试图预测什么样的地震？虽然一些科学家认为，大地震在大致相同的地方以大致相同的震级反复发生，但另一些人则指出了这种观点的重大错误。大地震有时会重叠，发生在不同的地方，合并成更大的地震或打破多个断层。在这个项目中，这个团队汇集了来自阿尔斯特大学和爱丁堡大学以及罗马国家地球物理和火山学研究所的科学家，他们将通过回顾过去而不是展望未来来检验相互作用应力的想法有多好。由于科学家们20多年来的共同努力，地球上很少有地方比我们对过去的大地震活动有更好的了解。我们有信心知道大约1600年以来在那里发生的所有地震的位置和大致大小（M bbbb6）。我们对板块汇聚也有很多了解，板块汇聚是地震产生的驱动力。在这个项目中，我们将把这些信息整合到一个复杂的数值模拟中，以重建过去400年来苏门答腊西部地区的整个应力场。由此产生的三维应力历史将使我们能够看到相互作用应力的想法是否可以用来解释过去400年的地震；这将有助于我们了解接下来可能发生的事情。此外，我们将研究最近的小地震记录，看看我们是否可以利用这些记录来告诉我们大地震的简单重复行为的可靠性。这个问题很复杂，需要非常仔细地应用统计技术，以确保我们得出正确的结论。我们将在项目期间开发其中的许多功能。西苏门答腊目前是世界上地震风险最高的地区之一。印度洋沿岸的居民，尤其是苏门答腊岛西海岸的居民，生活在另一场大地震的威胁之中，这场地震的死亡规模可能与节礼日地震的规模相当。这个项目不会阻止地震，但它将有助于建立科学知识体系，最终帮助人们做好应对地震的准备。

项目成果

Using a genetic algorithm to estimate the details of earthquake slip distributions from point surface displacements

使用遗传算法从点面位移估计地震滑动分布的细节

• DOI: 10.1002/2015jb012181
• 发表时间: 2016
• 期刊: Solid Earth
• 影响因子: 3.4
• 作者: Lindsay A

The Role of Stress Barriers on the Shape of Future Earthquakes in the Mentawai Section of the Sunda Megathrust

应力屏障对巽他巨型逆冲断层明打威段未来地震形状的作用

• DOI: 10.55730/1300-0985.1847
• 发表时间: 2023
• 期刊: Turkish Journal of Earth Sciences
• 影响因子: 1
• 作者: NALBANT S

The September 2009 Padang earthquake

2009 年 9 月巴东地震

• DOI: 10.1038/ngeo753
• 发表时间: 2010
• 期刊: Nature Geoscience
• 影响因子: 18.3
• 作者: McCloskey J