Fully Coupled Modeling of Dynamic Rupture, Wedge Plasticity, and Tsunami for Great Earthquakes in the Japan Trench

2011年日本东北部9级地震可能是世界上观测到的最好的大地震，但尽管如此，我们仍然不完全了解它是如何产生如此巨大和致命的海啸的。马博士和他的学生将使用复杂的计算机模型来测试这样一个想法，即海底厚厚的沙子和粘土沉积物在地震中比固体岩石变形更大，导致海底海拔变化更大，海啸更大。这就可以解释为什么在三陆海岸沿着会有巨大的海啸波，而三陆海岸位于东北大地震能量释放的北部。该计算机模型将使用日本过去产生海啸的地震数据进行测试，并将用于了解海啸开始时在海洋中产生的声波。声波在海洋中的传播速度比海啸波本身快得多，可以用来提高海啸预警的准确性。马博士和他的学生将通过开发2011年东北地震的动态破裂、楔形塑性和海啸的完全耦合模型来验证一个假设，即2011年三陆海岸沿着的大海啸是由日本海沟38.5°N以北的非弹性楔形变形引起的，这是由于厚沉积物的存在。完全耦合的模型保证了最准确的海洋声波和海啸的激励。这一为期三年的项目将包括以下活动：㈠开发2011年东北地震的自洽动态破裂模型，以解释重要的大地测量、地震、海啸和差分测深观测。(ii)通过完全耦合动态破裂和海啸模拟了1896年和1933年的三陆地震，并研究了这三次地震中海洋声波和海啸对浅层滑动和楔形塑性的敏感性。(iii)由于日本海沟和世界范围内的巨型逆冲断层和外隆正断层地震，确定可用于下一代海啸预警系统的海洋声波。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。

The 2011 magnitude 9 Tohoku Japan earthquake is probably the world's best observed great earthquake, but in spite of this we still do not fully understand how it generated such a large and deadly tsunami. Dr. Ma and his student will use sophisticated computer models to test the idea that thick deposits of sand and clay on the seafloor can deform more in an earthquake than solid rock, leading to more change in elevation of the seafloor and a bigger tsunami. This could explain the huge tsunami wave along the Sanriku coast, north of where most of the Tohoku earthquake's energy was unleashed. The computer model will be tested using data from past tsunami-producing earthquakes in Japan, and will also be used to understand sound waves that are generated in the ocean when a tsunami begins. Sound waves travel through the ocean much faster than the tsunami wave itself, and can be used to improve the accuracy of tsunami warnings. Dr. Ma and his student will test a hypothesis that the large 2011 tsunami along the Sanriku coast was caused by inelastic wedge deformation north of 38.5°N in the Japan Trench due to presence of thick sediments, by developing a fully-coupled model of dynamic rupture, wedge plasticity, and tsunami for the 2011 Tohoku earthquake. The fully-coupled model ensures the most accurate excitations of ocean acoustic waves and tsunami. This three-year project will include the following activities: (i) developing a self-consistent dynamic rupture model of the 2011 Tohoku earthquake that can explain important geodetic, seismic, tsunami, and differential bathymetry observations. (ii) simulating the 1896 and 1933 Sanriku earthquakes by fully coupling dynamic rupture and tsunami and investigating the sensitivities of ocean acoustic waves and tsunami to shallow slip and wedge plasticity in these three earthquakes. (iii) identifying ocean acoustic waves that can be used for next-generation tsunami early warning systems due to megathrust and outer-rise normal-faulting earthquakes in the Japan Trench and worldwide.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.