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.

俯冲带是地球构造板之一滑到另一个区域的区域。两个板之间的滑动区域是地质断层，其中下部板的运动通过摩擦过程不完美地转移到上覆板，从而使未发行的应变堆积在上板中。 上板中积累应变的突然释放会导致地震，由于滑动区域的大小，在俯冲带上可能很大。这些巨大的地震既造成了摇动本身的破坏，又是因为海水从海啸中泛滥。 2004年苏门答腊的最新事件，2010年的智利和2011年的日本都证明了与这些事件相关的毁灭性危害。 俯冲带也位于北加州北部，俄勒冈州和华盛顿州以及阿拉斯加和阿留申群岛的沿海地区。 这两个俯冲区过去曾经历过巨大的地震，将来会再次发生地震。该项目的一个目的是更好地了解俯冲区工作中工作中的地球物理过程，并改善对潜在危害的定量评估。该项目将部署海底大地测量传感器的组合，以跟踪新西兰俯冲带近海的缓慢积聚和可能释放海底运动。 由于俯冲带很浅，因此选择了新西兰山川站点，并且可以使用海底大地测量仪器进行成像。 该站点还具有快速重复慢速滑动地震的历史，可洞悉滑移过程。 该项目的更广泛的影响包括研究研究生的培训和支持。该项目利用新西兰和日本研究团队的国际努力，他们将占据邻近的海底大地测量场所。该项目还将转移操作知识，以如何将海底测量实验进行到新西兰研究对应物，从而使他们能够在该拟议项目期间在这些关键的地点进行测量，并在未来的未来继续进行。该项目将衡量。使用GPS-Asoustic（GPS-A）方法，在新西兰Hikuangi俯冲边缘的沟槽附近的变形。 GPS-A站点将在霍克斯湾地区建立，以提供以日本和新西兰资助建立的边缘北部和南部地区的GPS-A站点之间的关键测量。这个中央地点接近从明显的距离向南的距离，在北部几乎没有耦合的边缘。 该项目将为GPS声学测量实施更高效和省略成本的波滑翔机平台。将安装永久的海底基准测试，以确保可以在该项目结束的结束时继续前进的时间序列。还将部署一系列的绝对压力仪表，以测量霍克斯湾地区下面的陆地阵列观察到的慢速事件的近海程度，该地区据认为，基于古介质学，过去曾经历过许多8级地震。该阵列有望检测垂直提升，因此在部署期间，该地区至少有一个大型慢速事件的空间范围。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的智力优点和更广泛的评估来支持的。影响审查标准。

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