Collaborative Research: Along Strike Variation in Shallow, Offshore Strain Accumulation and Slow Slip at Hikurangi Subduction Margin, New Zealand

合作研究：新西兰 Hikurangi 俯冲边缘浅层近海应变积累和慢滑移的沿走向变化

• 批准号: 1754929
• 负责人: Spahr Webb
• 金额: $ 39.85万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-04-01 至 2024-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1754929&HistoricalAwards=false
• 关键词: Collaborative; Research; Along; Strike; Variation

Subduction zones are regions where one of Earth's tectonic plates slides beneath another. The zone of slip between the two plates is a geologic fault where the motion of the lower plate is imperfectly transferred to the overlying plate through frictional processes allowing for unreleased strain to build up in the upper plate. The abrupt release of built-up strain in the upper plate causes earthquakes, which can be large on subduction zones because of the size of the slip region. These great earthquakes cause damage both from the shaking itself but also because of the flooding of seawater from a tsunami. Recent events in Sumatra in 2004, Chile in 2010, and Japan in 2011 all demonstrate the devastating hazard associated with these events. Subduction zones also lie offshore the US coasts along Northern California, Oregon and Washington State and another along Alaska and the Aleutian Islands. Both of these subduction zones have experienced great earthquakes in the past and will do so again in the future. A goal of this project is to better understand the geophysical processes at work at subduction zones and to improve the quantitative assessment of potential hazard. This project will deploy a combination of seafloor geodetic sensors to track the slow buildup and possible release of seafloor motion offshore of a New Zealand subduction zone. The New Zealand Hikurangi site was picked because the subduction zone is shallow and can be imaged more effectively with seafloor geodetic instruments. This site also has a history of rapidly repeating slow slip earthquakes that provide insight into the slip process. Broader impacts of this project include training and support for a graduate student in the research. The project leverages international efforts by New Zealand and Japanese research teams who will occupy adjacent seafloor geodetic sites. The project will also transfer operational know-how for how to conduct seafloor geodesy experiments to NZ research counterparts, enabling them to collect measurements at these critical sites during this proposed project and continue in the future past the end of the project.This project will measure deformation near the trench of the New Zealand Hikuangi subduction margin over a four year period using the GPS-Acoustic (GPS-A) method. The GPS-A site will be established in the Hawkes Bay area to provide critical measurements centered between GPS-A sites in the northern and southern parts of the margin established using Japanese and New Zealand funding. This central site is near the transition from an apparently strongly coupled margin to the South, and a nearly uncoupled margin in the North. The project will implement the more efficient and cost-saving Wave Glider platform for the GPS-Acoustic measurements. Permanent seafloor benchmarks will be installed for horizontal positioning to ensure the time series of positions can be continued into the future, past the end of this project. An array of absolute pressure gauges will also be deployed for two years to measure the offshore extent of slow slip events observed from land arrays beneath the Hawkes Bay area, a region thought to have experienced many 8 magnitude earthquakes in the past based on paleoseismology. The array is expected to detect vertical uplift and hence the spatial extent of at least one large slow slip event in this region during the deployment.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.

俯冲带是地球的一个构造板块滑到另一个板块之下的区域。两个板块之间的滑动带是一个地质断层，其中下部板块的运动通过摩擦过程不完全地传递到上覆板块，从而允许未释放的应变在上部板块中积聚。 上板块中累积的应变突然释放会引起地震，由于滑动区的大小，地震在俯冲带上可能很大。这些大地震造成的破坏既来自震动本身，也来自海啸造成的海水泛滥。最近在2004年苏门答腊、2010年智利和2011年日本发生的事件都表明了与这些事件有关的毁灭性危害。 俯冲带也位于沿着北方加州、俄勒冈州和华盛顿州的美国海岸近海，另一个位于沿着阿拉斯加和阿留申群岛。 这两个俯冲带在过去都经历过大地震，未来也会再次发生。该项目的一个目标是更好地了解俯冲带的地球物理过程，并改进对潜在危险的定量评估。该项目将部署一系列海底大地测量传感器，以跟踪新西兰俯冲带近海海底运动的缓慢积累和可能释放。 之所以选择新西兰希库朗吉地点，是因为俯冲带较浅，可以用海底大地测量仪器更有效地成像。 该网站也有一个快速重复的缓慢滑动地震的历史，提供了深入了解滑动过程。 该项目更广泛的影响包括培训和支持研究生。该项目利用新西兰和日本研究小组的国际努力，这些研究小组将占用邻近的海底大地测量点。该项目还将向新西兰的研究同行转让如何进行海底大地测量实验的业务专门知识，使他们能够在拟议项目期间收集这些关键地点的测量结果，并在项目结束后继续进行，该项目将在四年期间使用GPS声学（GPS-A）方法测量新西兰Hikuangi俯冲边缘海沟附近的变形。将在霍克斯湾地区建立GPS-A站点，以利用日本和新西兰的资金建立的边缘北方和南部的GPS-A站点为中心提供关键测量。这个中心的网站是附近的过渡，从一个明显的强烈耦合的边缘到南部，和一个几乎不耦合的边缘在北部。 该项目将实施更有效和节省成本的Wave Glider平台，用于GPS声学测量。将安装永久海底基准进行水平定位，以确保位置的时间序列可以延续到未来，超过本项目的结束。一个绝对压力计阵列也将部署两年，以测量从霍克斯湾地区下面的陆地阵列观察到的缓慢滑动事件的离岸范围，根据古地震学，该地区过去曾经历过许多8级地震。该阵列预计将检测垂直隆起，从而在部署期间在该地区至少一个大的慢滑事件的空间范围。该奖项反映了NSF的法定使命，并已被认为是值得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的支持。

项目成果

Using Seafloor Geodesy to Detect Vertical Deformation at the Hikurangi Subduction Zone: Insights From Self‐Calibrating Pressure Sensors and Ocean General Circulation Models

• DOI: 10.1029/2022jb023989
• 发表时间: 2022-11
• 期刊: Journal of Geophysical Research: Solid Earth
• 作者: K. Woods;S. C. Webb;L. Wallace;Y. Ito;C. Collins;N. Palmer;R. Hino;M. K. Savage;D. Saffer;E. E. Davis-E.;D. Barker