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: 2314273
• 负责人: Eric Lindsey
• 金额: $ 32.19万
• 依托单位: University of New Mexico
• 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=2314273&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.

俯冲带地地震可能会导致海啸，这是一场致命的自然灾害。在过去的二十年中，海啸在土地海界附近产生的海啸造成了四分之一的死亡人数（2004年苏门答腊事件，地球最近最致命的自然灾害），损失了超过2000亿美元（日本2011年的活动，是历史上最昂贵的自然灾害之一）。将来的某个时候，类似的事件可能会袭击美国俄勒冈 - 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几种类型的工具，以测量可能是地震前体的海底小动作。结果将用于改善森林和对俯冲带地震和海啸的理解。该项目将在俯冲带的两个样本采样中，将部署新的，具有成本效益的最先进的海底大地测量设备。这两个部分在重要的地质和地球物理特征中对比，为假设测试大型属性特性在海啸中的作用提供了独特的机会。例如，在俯冲带的近沟区域中积累了浅层滑动防御，这是俯冲相关海啸的必要条件吗？可以通过比较中美洲俯冲带的两个相邻近海段中的应变率曲线来回答这个问题，以对比地震特征，锁定行为和海啸病史。哥斯达黎加的尼古亚半岛的地震生成区尽管经常在记录的历史中产生重要的海啸，尽管M 7.2 - 7.8地震，而北部尼加拉瓜北部的尼加拉瓜和萨尔瓦多北部的地震却在1992年和2012年产生了北部的海啸，预计北部的境内是不需要的，假设有必要的境内宣布是必要的，那是对tsunamis的必要条件。哥斯达黎加，但观察到尼加拉瓜南部的浅滑动防御（锁定？），这表明在未来几十年中有可能在那里发生海啸。一个微妙的是应力阴影效应的可能性，因此前臂的上倾角在摩擦上不是“锁定”的，而是“骑行”，尽管在财务上稳定，但板界面上的锁定性较深。沟渠 - 垂直的大地测试样品应允许评估这种可能性。该奖项反映了NSF的法定任务，并使用基金会的知识分子优点和更广泛的影响标准，被视为通过评估而被视为珍贵的支持。