Collaborative Research: Improved Understanding of Subduction Zone Tsunami Genesis Using Sea Floor Geodesy Offshore Central America

合作研究：利用中美洲近海海底大地测量学提高对俯冲带海啸成因的了解

• 批准号: 2314272
• 负责人: Surui Xie
• 金额: $ 25万
• 依托单位: University of Houston
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-01-01 至 2026-12-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2314272&HistoricalAwards=false
• 关键词: Collaborative; Research; Improved; Understanding; Subduction

Subduction zone earthquakes can cause tsunamis, a deadly natural disaster. In the last two decades tsunamis generated near the land-ocean boundary have caused a quarter of a million fatalities (the 2004 Sumatra event, Earth’s deadliest recent natural disaster) and losses more than $200 billion (Japan’s 2011 event, one of the most expensive natural disasters in history). A similar event is likely to hit the US Oregon-Washington coast sometime in the future. Unfortunately, the ability to forecast these catastrophic events is not very good. This project will deploy and test several types of instruments for measuring small motions of the seafloor that may be earthquake precursors. The results will be used to improve forecasts and understanding of subduction zone earthquakes and tsunamis. The project will deploy new, cost-effective state-of the art sea floor geodesy equipment offshore Central America, in two transects sampling adjacent segments of the subduction zone. The two segments contrast in important geological and geophysical characteristics, providing a unique opportunity for hypothesis testing of the role of megathrust properties in tsunami generation. For example, is accumulation of shallow slip deficit in the near-trench region of subduction zones a necessary condition for a subduction-related tsunami? The question can be answered by comparing strain rate profiles in two adjacent offshore segments of the Central America subduction zone that contrast in earthquake characteristics, locking behavior, and tsunami history. The seismogenic zone offshore the Nicoya peninsula of Costa Rica has not produced a significant tsunami in recorded history despite frequent M 7.2 – 7.8 earthquakes, while the one to the north offshore Nicaragua and El Salvador generated tsunamis in 1992 and 2012. Assuming slip deficit accumulation is a necessary condition for tsunamis, the project would expect to observe no slip deficit in the offshore region of northern Costa Rica but observe a shallow slip deficit (locking?) in southern Nicaragua, indicating the potential for another tsunami there in the next few decades. One subtlety is the possibility of stress shadow effects, whereby up-dip sections of the forearc are not frictionally ‘locked’ but rather ‘ride along’ with deeper locked asperities on the plate interface, accumulating a partial slip deficit despite being frictionally stable. The trench-perpendicular geodetic transects should allow assessment of this possibility.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.

俯冲带地震可能引发海啸，这是一种致命的自然灾害，在过去二十年中，陆地与海洋边界附近发生的海啸已造成 25 万人死亡（2004 年苏门答腊岛事件，地球上最近最严重的自然灾害），损失超过 200 美元。亿美元（日本 2011 年发生的事件，是历史上损失最惨重的自然灾害之一）。类似的事件可能会在 2011 年的某个时候袭击美国俄勒冈-华盛顿海岸。不幸的是，预测这些灾难性事件的能力不是很好，该项目将部署和测试多种类型的仪器，用于测量可能是地震前兆的海底小运动。该项目将在中美洲近海部署新的、具有成本效益的最先进的海底大地测量设备，对俯冲带的相邻部分进行采样，这两个部分在重要的地质和地球物理方面形成鲜明对比。特征，为检验巨型逆冲特性在海啸产生中的作用提供了独特的机会，例如，俯冲带近海沟区域浅层滑移缺陷的积累是否是俯冲相关海啸的必要条件？可以通过比较中美洲俯冲带两个相邻近海部分的应变率剖面来回答，这些剖面在地震特征、锁定行为和海啸历史上形成对比。哥斯达黎加尼科亚半岛近海的地震带尚未产生地震。尽管频繁发生里氏 7.2 至 7.8 级地震，但尼加拉瓜和萨尔瓦多北部近海的地震在 1992 年和 2012 年引发了海啸，这是历史上有记录的重大海啸。假设滑动赤字积累是海啸的必要条件，该项目预计不会观察到滑动哥斯达黎加北部近海地区存在赤字，但在尼加拉瓜南部观察到浅滑移赤字（锁定？），表明有可能再次发生海啸在接下来的几十年里，一个微妙之处是应力阴影效应的可能性，即前弧的上倾部分不会被摩擦“锁定”，而是与板界面上更深的锁定粗糙体“一起行驶”，从而积累部分滑移。尽管摩擦力稳定，但与沟槽垂直的大地测量横断面应该允许评估这种可能性。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。