Subduction Zone Coupling and Strain Partitioning in the Philippine Plate Boundary Zone

这个试点研究项目旨在通过使用高精度GPS测量分析表面变形场，研究菲律宾岛弧上一个复杂的、俯冲主导的板块边界带的活动构造过程。该项目利用了菲律宾火山和地震学研究所（PHIVOLCS）与国际合作者一起收集的菲律宾板块边界带连续和运动GPS站点的240个站点网络的最新数据。该项目建立在印第安纳大学、PHIVOLCS和台湾两家研究机构之间成功的研究合作基础上。工作重点是：(1)改进菲律宾岛弧区域板块运动和板内变形模型；(2)吕宋岛俯冲相关压缩和弧内剪切变形之间的应变分配评估，包括1990年吕宋岛7.7 Mw大地震的震后瞬态效应评估；(3)马尼拉-菲律宾海沟空间变化俯冲带耦合及其对地震潜势的影响。这项建议力求与菲律宾和台湾的对应机构合作，通过分析现有的地壳变形数据，延长和扩大正在吕宋岛进行的研究。任务包括(1)将弹性块相互作用的运动学建模扩展到整个菲律宾群岛；(2)建立了菲律宾断裂带断裂相关变形及与俯冲边界相互作用的三维变形块体模型；(3)通过对俯冲带爬行段和闭锁段的动态模拟，研究马尼拉和菲律宾俯冲带的空间变量耦合。板块边界地震势的预期模型可以作为地震动和海啸发生模型的输入。该项目具有重大的社会影响，其形式是改进了在活动板块边界带检测断层相关变形和俯冲带活动的方法。特别是，这些观测将为评估菲律宾的长期地震危险提供关键信息。PHIVOLCS和其他菲律宾合作者为向发展中世界的同事转让技术提供了途径。由于大量人口面临未来地震和相关次生影响的风险，作为该项目的一部分进行的研究可能对菲律宾的减灾工作产生重大影响。该项目将为印第安纳大学的学生和正在进行的科学推广活动提供支持。

This pilot research project seeks to examine active tectonic processes in a complex, subduction-dominated plate boundary zone in the Philippines island arc through analysis of the surface deformation field using high-precision GPS measurements. The project takes advantage of a newly available suite of data from a 240-station network of continuous and campaign GPS sites in the Philippine plate boundary zone, collected by the Philippine Institute of Volcanology and Seismology (PHIVOLCS), together with international collaborators. The project builds on a successful research collaboration between Indiana University, PHIVOLCS, and two research institutes in Taiwan. The work will focus on (1) improvement of regional plate motion and intraplate deformation models for the Philippine island arc; (2) evaluation of strain partitioning between subduction-related compression and intra-arc shear deformation in Luzon, including assessment of post-seismic transient effects associated with the large (Mw 7.7) 1990 Luzon earthquake; and (3) assessment of spatially variable subduction zone coupling along the Manila and Philippine trenches and its impact on earthquake potential. This proposal seeks to extend and expand the ongoing studies in Luzon through analysis of existing crustal deformation data, in collaboration with Philippine and Taiwanese counterparts. Tasks include (1) extending kinematic modeling of elastic block interaction to include the entire Philippine archipelago; (2) developing 3-D deforming block models of fault-related deformation at the Philippine Fault and interaction with subduction boundaries; and (3) examining spatially variable coupling along the Manila and Philippine subduction zones through dynamic modeling of subduction-zone creeping and locked segments. The expected models of plate boundary earthquake potential can be used as input for ground-motion and tsunami-generation models.This project has significant societal impacts in the form of improved methods for detecting fault-related deformation and subduction-zone activity in active plate boundary zones. In particular, these observations will provide critical information for assessment of long-term seismic hazards for the Philippines.PHIVOLCS and other Philippine collaborators provides an avenue for technology transfer to colleagues in the developing world. Because of the large population at risk from future earthquakes and related secondary effects, the research conducted as part of this project could have significant impacts in hazard mitigation for the Philippines. The project would provide support for students at Indiana University and ongoing science outreach activities.