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

海底地震能够产生不同寻常的大海啸，并大大增加目前生活在沿着的世界上大多数人口所面临的危险。目前用于研究海底地震的技术非常昂贵，并且无法应用于大多数感兴趣的地震。由于缺乏观测，人们无法了解地震是否会使海底移位，并增加产生重大海啸的可能性。该项目中开发的理论将为研究具有重大科学和社会意义的海底地震提供新的基础工具。将开发一个新的框架，克服以前的理论局限性，使我们能够开发一个易于使用的，廉价的工具，这将允许从地面运动的远程记录单独的海底滑动检测。 然后，该工具将用于检查过去15年中产生毁灭性海啸的大地震，以及最近世界各地的中等规模地震。通过使用新开发的工具研究大量地震，将更好地了解为什么有些地震会移动海底，而另一些则不会。 该项目可以为海啸灾害评估提供改进。 该项目支持培训一名博士后研究员，第一部分将建立必要的理论和观测框架，以区分滑移到达和没有到达地表的事件。这一理论将提供一个简单的地震诊断工具，并具有补充数值模型，海底仪器，钻井或海洋调查的额外好处。该项目的第二个组成部分将提供必要的观测，通过对全球地震网记录的大量事件的长期地震数据进行诊断，确定控制海底表面破裂的物理机制。新框架将使用2011年东北冲地震期间测量到的大量浅层滑动进行验证。将确定在巨型逆冲断层地震（如2010年和2015年智利地震和2004年和2010年苏门答腊海啸地震）以及最近的中等规模地震中观察到的这种类型的浅层滑动的程度。利用对大、中地震的调查结果，将试图确定断层带的性质（例如，加积楔的存在、俯冲沉积厚度、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知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

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.