Geodetic Observations in the Northern Costa Rica Subduction Zone

哥斯达黎加北部俯冲带的大地测量观测

• 批准号: 1835947
• 负责人: Timothy Dixon
• 金额: $ 29.41万
• 依托单位: University of South Florida
• 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: 2019-07-15 至 2023-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1835947&HistoricalAwards=false
• 关键词: Geodetic; Observations; Northern; Costa; Rica

The great earthquakes and tsunamis of 2004 (Sumatra) and 2011 (Japan) were wake-up calls that our forecasting skill for these catastrophic events remains weak. Measurement of the slow motions of the Earth's surface near active faults could help to forecast the location and the size of future earthquakes. This project tests the concept by operating a network of a high precision GPS receivers in Costa Rica. This area is an active subduction zone that experiences frequent large earthquakes. The GPS units will measure ground motion for a 3-year period with a precision of a few millimeters per day. This will continue a long history of geodetic observations here that now span both the late and early stages of the earthquake cycle. The data from this project will improve understanding of the earthquake process, and could lead to improvements in our ability to forecast these potentially deadly events. UNAVCO, the NSF-funded consortium for geodesy, will provide critical maintenance support for the network. The broader impacts of the study include impacts on earthquake hazards and also help to train the next generation of scientists through support for a PhD graduate student. The existence of earthquake clusters in subduction interfaces suggests that not all accumulated strain is necessarily released in an earthquake, and can be stored over a seismic cycle for release in a subsequent, larger than average event. With the discovery of slow slip events (SSEs: earthquake-like phenomenon within the interseismic phase that release energy slowly) it is now clear that determination of a full strain accumulation budget, and improved understanding of frictional conditions on the plate interface, also require study and understanding of these interseismic strain release mechanisms. Data from the 2012 Costa Rica earthquake suggests that a pre-event SSE changed Mohr Coulomb failure stress by a trivial amount, although other failure mechanisms are possible. SSEs are also important indicators of frictional conditions. Shallow SSEs are an important subset, and while generally difficult to observe, can be clearly seen in northern Costa Rica due to proximity to the trench. They may be critical for understanding tsunami potential in this difficult-to-observe region. More generally, SSEs may outline the region of subsequent seismic rupture, this pattern has now been documented in the active margins off Costa Rica, Ecuador and parts of Japan. This project deploys geodetic infrastructure to better observe and understand these slow slip events in the Nicoya Peninsula.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.

2004年（苏门答腊）和2011年（日本）的大地震和海啸是我们对这些灾难性事件的预测技能仍然很弱的唤醒呼吁。测量地球表面靠近主动断层的缓慢运动可能有助于预测未来地震的位置和大小。该项目通过在哥斯达黎加的高精度GPS接收器网络操作网络来测试该概念。该区域是一个活跃的俯冲带，经常发生大地震。 GPS单元将在3年期间测量地面运动，每天精确数毫米。这将在这里持续悠久的大地观测历史，现在跨越地震周期的晚期和早期阶段。该项目的数据将改善对地震过程的理解，并可能改善我们预测这些潜在致命事件的能力。 NSF资助的Geodesy财团Unavco将为网络提供关键的维护支持。该研究的更广泛影响包括对地震危害的影响，还可以通过支持博士研究生来培训下一代科学家。俯冲界面中的地震簇的存在表明，并非所有累积的应变都必须在地震中释放，并且可以在地震循环中存储，以便在随后的，大于平均事件中释放。随着发现缓慢的慢速事件的发现（SSE：地震样现象，在慢慢释放能量的情况下，释放能量的现象）现在很明显，确定完全应变的积累预算，并提高对板界面上摩擦条件的理解，还需要研究和了解这些间歇性释放机制。 2012年哥斯达黎加地震的数据表明，事件前的SSE尽管可能实现了其他故障机制，但事件前的SSE将MOHR库仑衰竭应力改变了一定程度。 SSE也是摩擦条件的重要指标。浅层SSE是一个重要的子集，尽管通常很难观察，但由于距离沟渠的距离，哥斯达黎加北部可以清楚地看到。它们可能对于理解这个难以挑选的地区的海啸潜力至关重要。更普遍地，SSE可以概述随后的地震破裂区域，现在已经在哥斯达黎加，厄瓜多尔和日本部分地区的主动利润中记录了这种模式。该项目部署了大地基础设施，以更好地观察和理解尼科亚半岛中的这些慢速事件。该奖项反映了NSF的法定任务，并且使用基金会的知识分子优点和更广泛的影响审查标准，被认为值得通过评估来获得支持。