Collaborative Research: Seismic Investigation of the Puerto Rico Subduction Zone: Structure, Seismic Hazard, and Hydration of Slow-spreading Lithosphere

合作研究：波多黎各俯冲带的地震调查：结构、地震危险性和缓慢扩张岩石圈的水合作用

• 批准号: 2001776
• 负责人: Shuoshuo Han
• 金额: $ 35.05万
• 依托单位: University of Texas at Austin
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-08-01 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2001776&HistoricalAwards=false
• 关键词: Collaborative; Research; Seismic; Investigation; Puerto

Seismic investigation of the Puerto Rico subduction zoneThe Puerto Rico Trench (PRT) poses major earthquake and tsunami hazards. Tsunamis generated at this subduction zone may also impact the U.S. East Coast. This project supports land and sea seismic experiments across the PRT and Puerto Rico. The experiments will define the detailed seismic structure of the PRT, advance our understanding of the PRT, and improve hazard assessment. The project consists of: (1) Three wide-angle seismic reflection/refraction profiles using ocean bottom seismometers (OBS); (2) Four multichannel seismic (MCS) reflection profiles, two parallel to and inland from the trench, and two parallel to the central OBS profile. (3) An array of more than 100 short-period land seismometers deployed across the Puerto Rico island, together with a dozen broad-band seismometers to record earthquakes for 18 months. The project will provide support for training several graduate students and an early career scientist, as well as research opportunities for faculty and students at a minority serving institution. The project will also support training of science journalists and public lectures to reach Puerto Rico residents.This project supports an active-source seismic experiment across the Puerto Rico Trench (PRT), its outer rise, and across the island arc, together with a land passive-source experiment. The PRT is a highly oblique subduction zone, where old Atlantic plate subducts under the Caribbean plate at a slow rate. The PRT is associated with anomalous and unexplained characteristics, such as the widest trench (below 6,000 m), the lowest gravity anomaly on Earth, and anomalous subsidence of the north coast of Puerto Rico. This project will acquire, analyze, and interpret multiple types of data: Three wide-angle seismic reflection/refraction profiles across the PRT with OBSs and an additional line south of the Puerto Rico island; four MCS reflection profiles, two each parallel and perpendicular to the PRT axis; an array of active- and passive-source land seismic stations on the Puerto Rico island; and multibeam bathymetry, 3.5 kHz sub-bottom profiler, gravity, and magnetics. The experiments are designed to address three key questions: (1) What is the shallow geometry of the subducting slab and its lateral continuity along the 500-km section of the trench? (2) What are the degree and spatial extent of hydration of the Atlantic lithosphere entering the Puerto Rico Trench? (3) Does oceanic bivergent thrust system represent double-sided subduction or a crustal retro-wedge of one-sided subduction? Results of the integrated seismic experiments are expected to significantly advance our understanding of the above scientific questions and assessment of the PRT seismic and tsunami hazard.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.

波多黎各俯冲带的地震调查波多黎各海沟（PRT）造成重大地震和海啸灾害。该俯冲带产生的海啸也可能影响美国东海岸。该项目支持 PRT 和波多黎各的陆地和海上地震实验。这些实验将定义 PRT 的详细抗震结构，加深我们对 PRT 的理解，并改进灾害评估。该项目包括：（1）使用海底地震仪（OBS）的三个广角地震反射/折射剖面； (2) 四个多道地震 (MCS) 反射剖面，两个平行于海沟并位于海沟内，两个平行于中央 OBS 剖面。 (3) 在波多黎各岛上部署了 100 多个短期陆地地震仪阵列，以及十几个宽带地震仪，可记录 18 个月的地震。该项目将为培养几名研究生和一名早期职业科学家提供支持，并为少数族裔服务机构的教师和学生提供研究机会。该项目还将支持对波多黎各居民进行科学记者培训和公开讲座。该项目支持横跨波多黎各海沟（PRT）、其外隆起以及整个岛弧以及陆地的主动源地震实验被动源实验。 PRT是一个高度倾斜的俯冲带，旧大西洋板块以缓慢的速度俯冲到加勒比板块之下。 PRT 与异常和无法解释的特征有关，例如最宽的海沟（低于 6,000 m）、地球上最低的重力异常以及波多黎各北海岸的异常沉降。该项目将采集、分析和解释多种类型的数据： PRT 上的三个广角地震反射/折射剖面，带有 OBS 和波多黎各岛以南的一条附加线；四个 MCS 反射轮廓，平行和垂直于 PRT 轴各两个；波多黎各岛上的一系列主动和被动源陆地地震台；多波束测深、3.5 kHz 海底剖面仪、重力和磁学。这些实验旨在解决三个关键问题：（1）俯冲板片的浅层几何形状及其沿海沟 ​​500 公里部分的横向连续性是什么？ (2) 大西洋岩石圈进入波多黎各海沟的水化程度和空间范围是多少？ （3）大洋双叉逆冲系统代表的是双面俯冲还是地壳后向楔形的单侧俯冲？综合地震实验的结果预计将显着促进我们对上述科学问题的理解以及对 PRT 地震和海啸灾害的评估。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力优势和更广泛的评估进行评估，被认为值得支持。影响审查标准。