Elucidating the Mechanics of Tsunami Generating Earthquake Rupture with Long Period Seismology

用长周期地震学阐明海啸引发地震破裂的机制

• 批准号: 1850831
• 负责人: Miaki Ishii
• 金额: $ 29.06万
• 依托单位: Harvard University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-05-01 至 2021-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1850831&HistoricalAwards=false
• 关键词: Elucidating; Mechanics; Tsunami; Generating; Earthquake

Submarine earthquakes are capable of generating uncharacteristically large tsunamis, and drastically increase the hazard facing most of the world's population, which currently lives along the coastlines. Current techniques used to study submarine earthquakes are expensive and cannot be applied to most earthquakes of interest. The lack of observations has hindered the understanding of whether an earthquake will displace the seafloor and increase the likelihood of generating a significant tsunami. The theory developed in this project will provide a new fundamental tool for the study of submarine earthquakes with significant scientific and societal implications. A new framework will be developed that overcomes previous theoretical limitations and allows us to develop an easily utilized, inexpensive tool which will allow for the detection of slip on the seafloor from distant recordings of ground motion alone. This tool will then be used to examine giant earthquakes in the last 15 years that produced devastating tsunamis, as well as recent moderate-size earthquakes from around the world. By studying a large number of earthquakes with the newly developed tool, a better understanding will be obtained of why some earthquakes displace the seafloor while others do not. This project could provide an improvement for tsunami hazard assessment. The project supports the training of a postdoctoral investigator.The first component of this project will establish the theoretical and observational framework required to distinguish events for which slip reached and did not reach the surface. This theory will provide a simple seismological diagnostic tool, and has the added benefit of complementing numerical models, seafloor instrumentation, drilling, or marine surveys. The second component of this project will provide the necessary observations required to determine the physical mechanisms controlling submarine surface rupture by applying the diagnostic to long-period seismic data from a large number of events recorded by the Global Seismographic Network. The new framework will be validated using the large amount of shallow slip that was measured to have occurred during the 2011 Tohoku-Oki Earthquake. To what extent this type of shallow slip is observed in giant megathrust earthquakes, such as the 2010 and 2015 Chile and the 2004 and 2010 Sumatra tsunami earthquakes, as well as recent moderate-size earthquakes will be determined. Using the outcome of the survey of large and moderate-size earthquakes, an attempt will be made to determine the properties of fault zones (e.g., presence of accretionary wedge, subducted sediment thickness, fault dip-angle, etc.) that govern the rupture of the shallowest part of plate boundary.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

海底地震能够引发异常大的海啸，并极大地增加目前生活在海岸线的世界上大多数人口面临的危险。目前用于研究海底地震的技术非常昂贵，并且不能应用于大多数感兴趣的地震。缺乏观测阻碍了人们对地震是否会移动海底并增加发生严重海啸的可能性的了解。该项目开发的理论将为研究海底地震提供新的基本工具，具有重大的科学和社会意义。将开发一个新的框架，克服以前的理论限制，并使我们能够开发一种易于使用、廉价的工具，该工具将允许仅通过遥远的地面运动记录来检测海底的滑动。 然后，该工具将用于检查过去 15 年中引发毁灭性海啸的大地震，以及最近世界各地发生的中型地震。通过使用新开发的工具研究大量地震，我们将更好地理解为什么有些地震使海底移位，而另一些地震却没有。 该项目可以改进海啸灾害评估。 该项目支持培训一名博士后研究员。该项目的第一个组成部分将建立区分滑移到达和未到达表面的事件所需的理论和观察框架。该理论将提供一种简单的地震诊断工具，并具有补充数值模型、海底仪器、钻探或海洋调查的额外好处。该项目的第二部分将通过对全球地震网络记录的大量事件的长周期地震数据进行诊断，提供确定控制海底表面破裂的物理机制所需的必要观测。新框架将利用 2011 年东北冲地震期间测量到的大量浅层滑移进行验证。将确定在特大逆冲地震（例如 2010 年和 2015 年智利地震、2004 年和 2010 年苏门答腊岛海啸地震）以及最近的中等规模地震中观察到这种类型的浅滑的程度。利用大中型地震的调查结果，将尝试确定控制破裂的断层带特性（例如，是否存在增生楔、俯冲沉积物厚度、断层倾角等）。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。