Three Dimensional Seismic Velocity Structure of Puerto Rico Virgin Island Microplate

波多黎各维尔京群岛微板三维地震速度结构

• 批准号: 1722991
• 负责人: Elizabeth Vanacore
• 金额: $ 9.51万
• 依托单位: University of Puerto Rico Mayaguez
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-08-15 至 2021-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1722991&HistoricalAwards=false
• 关键词: Three; Dimensional; Seismic; Velocity; Structure

This project aims to study the structure and tectonics of the Puerto-Rico and Virgin Islands region located at the northeastern border of the Caribbean Plate. In this region, the North American plate is subducting beneath the Caribbean Plate. This interaction between the North American and Caribbean Plates results in significant earthquake activity including the 1918 earthquake and tsunami that devastated western coast of Puerto Rico. Currently, there are multiple tectonic models proposed to describe the interaction between the two plates. However, these models are currently poorly constrained by the available analyzed datasets. The primary goal of this project is to generate high quality seismic velocity images and refined earthquake location data that will provide data based constraints for the regional scientific models and enhance knowledge of the regional earthquake and tsunami hazard. This scientific study will involve two major processes, a relocation of the Puerto Rico Seismic Network earthquake catalog for the years 2015-2017 and a three-dimensional seismic velocity imaging of the region. This time period has been specifically selected to create a synergetic dataset with a current seismic experiment in the Dominican Republic (eastern Hispaniola). The direct data tie between this project and the project in Hispaniola will permit the future combination of the two separate datasets, the creation unified products, and promote scientific partnerships in the region. The first methodology to be applied in this study, earthquake relocation, is the process in which the earthquake locations determined by regional seismic networks and the United States Geological Survey (USGS), which are real-time fast solutions designed to provide information to emergency agencies, are re-examined in detail and refined using more advanced but time consuming computer algorithms as well as additional data that was not available in real-time to generate more accurate locations. The second methodology of this study, travel time tomography, is a method in which a three-dimensional seismic velocity image of the Puerto Rico-Virgin Islands region will be produced in a procedure analogous to how the human body is imaged in a medical CT scan. The imaging to be performed in this study will reveal the regional structure of the Earth's crust and upper mantle. This image combined with the relocated earthquake catalog will provide a robust view of the active tectonic processes that drive the observed regional seismic activity and provide data constraints for future scientific tectonic models. The products generated by this investigation, the relocated earthquake location catalog and seismic velocity imaging, will not only enhance scientific knowledge but also enhance the knowledge of the local earthquake and tsunami hazard. The relocation of local events will permit the identification of the most active faults within the Puerto Rico and Virgin Islands region, especially in Great Southern Puerto Rico Fault Zone and Great Northern Puerto Rico Fault Zone. Consequently, this will aid in the process of updating the Puerto Rico seismic hazard map which has not been revised by the USGS since 2003. The three-dimensional seismic velocity model will be used to determine if the current Puerto Rico Seismic Network one-dimensional velocity model used for earthquake location requires an update. The results of this study will be presented to the general public as short articles in the University of Puerto Rico Mayagüez website and Puerto Rico Seismic Network outreach materials, which impacts hundreds of school children and teachers throughout Puerto Rico every year. This research will also enhance participation of underrepresented students and faculty in the geosciences. The master's student at University of Puerto Rico Mayagüez (a Hispanic Serving Institution) will be funded to conduct the research as part of his/her thesis. The student and principal investigator will also present their research in national meetings and publish in peer-reviewed journals. This study proposes to focus on the seismic structure of the Puerto Rico-Virgin Islands Microplate (PRVIM), one of several proposed microplates in the deformation zone of the northeastern Caribbean margin. Of particular interest is the structure and dynamics of the subducting North American Plate beneath the PRVIM. Multiple tectonic models have been proposed for the dynamics across Hispaniola and the PRVIM. However, these models are currently poorly constrained by the available analyzed datasets. The primary goal of this project is to generate high quality seismic velocity images and refined earthquake location data that will provide data based constraints for the regional scientific models and enhance knowledge of the regional earthquake and tsunami hazard. This scientific study will involve two major processes, a relocation of the Puerto Rico Seismic Network earthquake catalog for the years 2015-2017 and a three-dimensional seismic tomography. This time period has been specifically selected to create a synergetic dataset with a current seismic experiment in the Dominican Republic (eastern Hispaniola). The direct data tie between this project and the project in Hispaniola will permit the future combination of the two separate datasets, the creation unified products, and promote scientific partnerships in the region. This project will generate a relocated event catalog dataset to sharpen the structures that are imaged on the PRVIM via seismicity including the Great Northern Puerto Rico Fault Zone, the subducted North American plate, and possible slab tears in the Mona Passage and Sombrero Seismic Zone. Additionally, a three-dimensional tomography using the FMTOMO program will be performed to image the detailed seismic velocity structure and aid in the identification/corroboration of significant seismic features related to the oblique subduction system. The detailed seismic imaging of this relatively understudied subduction zone will provide insight into the slab structure and dynamics of this oblique margin. The earthquake relocation and tomographic imaging aim to provide a high-resolution picture of the subducting slab structure beneath the PRVIM as well as determine if the two earthquake swarm locations denote slab tears similar to what has been imaged on the south side of the Caribbean Plate by the BOLIVAR project. The high-resolution imaging will also provide seismic constraints for future geodynamic models. In addition to increasing the understanding of the dynamics of oblique subduction zone, the products of this proposal will permit the identification of the most active faults within the PRVIM, especially in Great Southern Puerto Rico Fault Zone and Great Northern Puerto Rico Fault Zone. Consequently, this will aid in the process of updating the Puerto Rico seismic hazard map which has not been revised by the USGS since 2003. The updated three-dimensional seismic velocity model will be used to determine if the current Puerto Rico Seismic Network one-dimensional velocity model used for earthquake requires an update. The results of this study will be presented to the general public as short articles in the University of Puerto Rico Mayagüez website and Puerto Rico Seismic Network outreach materials, which impacts hundreds of school children and teachers throughout Puerto Rico every year. This research will also enhance participation of underrepresented students and faculty in the geosciences. The master's student at University of Puerto Rico Mayagüez (a Hispanic Serving Institution) will be funded to conduct the research as part of his/her thesis. The student and primary investigator will also present their research in national meetings and publish in peer-reviewed journals.

该项目旨在研究位于加勒比海板块东北边界的波多黎各和维尔京群岛地区的结构和构造。在该地区，北美板块在加勒比海板下方俯冲。北美和加勒比海板之间的这种相互作用导致了重大的地震活动，包括1918年的地震和海啸破坏了波多黎各西部海岸。当前，提出了多种构造模型来描述两个板之间的相互作用。但是，这些模型目前受到可用分析数据集的约束。该项目的主要目标是生成高质量的地震速度图像和精致的地震位置数据，该数据将为区域科学模型提供基于数据的约束，并增强对区域地震和海啸危害的知识。这项科学研究将涉及两个主要过程，即2015 - 2017年的波多黎各地震网络地震目录以及该地区的三维地震速度成像。该时期已被专门选择用于在多米尼加共和国（东hispaniola）当前的地震实验创建协同数据集。该项目与Hispaniola项目之间的直接数据联系将允许两个单独的数据集（创建统一产品）的未来组合，并促进该地区的科学合作伙伴关系。这项研究中要应用的第一种方法是地震搬迁，是由区域地震网络和美国地质调查（USGS）确定的地震位置（USGS），它们是实时快速解决方案，旨在为紧急机构提供信息，并使用更多的高级计算机algoriths以及其他可用的数据进行精确地进行了详细研究，并且可用的其他数据可用。这项研究的第二种方法是旅行时间断层扫描，是一种方法，其中将在波多黎各岛地区的三维地震速度图像中产生类似于与医学CT扫描中人体成像的方法相似的程序。在这项研究中进行的成像将揭示地壳和上地幔的区域结构。该图像与重新位置的地震目录相结合，将为主动构造过程提供良好的视图，这些过程驱动观察到的区域地震活动，并为未来的科学构造模型提供数据约束。这项投资，重新定位的地震位置目录和地震速度成像产生的产品不仅会增强科学知识，而且还可以增强对当地地震和海啸危害的知识。波多黎各和维尔京群岛地区内的主动断层，尤其是在波多黎各大南部的断层区和大波多黎各断层区。因此，这将有助于更新波多黎各地震危险图，该地图自2003年以来一直没有由USGS进行修订。三维的地震速度模型将用于确定当前的波多黎各地震网络网络是否用于地震位置需要更新。这项研究的结果将在波多黎各大学网站和波多黎各地震网络外展材料中以短篇文章的形式提交给公众，这每年都会影响整个波多黎各的数百名小学生和老师。这项研究还将加强代表性不足的学生和教职员工参与地球科学。波多黎各玛雅尔大学（西班牙裔服务机构）的硕士学生将作为他/她的论文的一部分进行研究。学生和首席调查员还将在国家会议上介绍他们的研究，并在同行评审期刊上发布。这项研究的提议旨在集中于波多黎各维尔金岛微板岩（PRVIM）的地震结构，这是东北加勒比海边缘变形区的几种拟议的微板之一。特别有趣的是俯冲北美板块下方的结构和动力学。已经提出了多种构造模型，用于西班牙裔和prvim的动力学。但是，这些模型目前受到可用分析数据集的约束。该项目的主要目标是生成高质量的地震速度图像和精致的地震位置数据，该数据将为区域科学模型提供基于数据的约束，并增强对区域地震和海啸危害的知识。这项科学研究将涉及两个主要过程，即2015 - 2017年的波多黎各地震网络地震目录和三维地震层析成像。该时期已被专门选择以在多米尼加共和国（东方）西班牙裔的当前地震实验中创建一个协同数据集。该项目与Hispaniola项目之间的直接数据联系将允许两个单独的数据集（创建统一产品）的未来组合，并促进该地区的科学合作伙伴关系。该项目将生成一个重新定位的事件目录数据集，以通过地震性在Prvim上成像的结构，包括大波多黎各断层区，俯冲的北美板块，以及Mona Passage和Sombrero地震层的可能的平板撕裂。此外，将使用FMTOMO程序进行三维层析成像，以对详细的地震速度结构进行图像，并有助于鉴定/佐证与斜俯冲系统相关的重要地震特征。这个相对理解的俯冲带的详细地震成像将提供对斜缘的平板结构和动力学的洞察力。地震搬迁和断层成像旨在提供prvim下方的俯冲平板结构的高分辨率图片，并确定两个地震群位置是否表示与Bolivar Project通过Bolivar Project在加勒比海板南侧成像的板撕裂相似。高分辨率成像还将为未来的地球动力学模型提供地震限制。除了增加对倾斜俯冲区动力学的理解外，该提案的产物还将允许识别Prvim内最活跃的断层，尤其是在波多黎各大南部的大港口断层区和大波多黎各断层区。因此，这将有助于更新自2003年以来USGS未经修订的波多黎各地震危险图的更新。更新的三维地震速度模型将用于确定当前的波多黎各现有网络网络网络是否用于地震是否需要更新。这项研究的结果将在波多黎各大学网站和波多黎各地震网络外展材料中以短篇文章的形式提交给公众，这每年都会影响整个波多黎各的数百名小学生和老师。这项研究还将加强代表性不足的学生和教职员工参与地球科学。波多黎各玛雅尔大学（西班牙裔服务机构）的硕士学生将作为他/她的论文的一部分进行研究。学生和小学调查员还将在国家会议上介绍他们的研究，并在同行评审期刊上发表。