Collaborative Research: Revealing interseismic crustal deformation in the fold-and-thrust belt in western Taiwan from geodesy and seismology

台湾是世界上最活跃的构造板块边界之一。菲律宾海板块和欧亚板块之间的高碰撞速率在台湾西部形成了一系列被称为褶皱冲断带的丘陵和山脉。在过去的100年里，这条带至少发生了10次强烈地震。每年，这条褶皱冲断带可容纳超过1.6英寸的板块缩短，使台湾西部成为了解山脉形成和地震发生的理想天然实验室。这项为期三年的提案支持两名终身教职早期教师和一名女研究生，以扩大科学、技术、工程和数学(STEM)领域的多样性。其中一些产品可以整合到马里兰州日开放参观活动的外展套餐中。这套程序包是为普通公众设计的，用于学习不同构造环境下的活动板块构造、地震旋回和自然灾害。此外，该项目还促进了美国和台湾几个机构之间的合作。这项工作的分析和结果与台湾西部地区的地震危险性评估有直接关系。该团队将大地测量和地震测量结合起来，以回答下列科学问题：(1)台湾褶皱冲断带的地表形变特征是什么？(2)褶皱冲断带内不同深度的主地壳缩短方向是否一致？(3)我们能否利用地震学、大地测量学和数值模拟来识别台湾西部褶皱冲断带不同部分的活动断裂和计算滑动预算？该团队利用连续全球导航卫星系统(CGNSS)和干涉合成孔径雷达(InSAR)超过15年的位移，以估计台湾西麓约100英尺空间分辨率的三维地表形变。他们还利用台湾地震目录的高分辨率地震数据与GNSS和InSAR的测量结果进行比较。结合这些测量，他们可以综合分析不同深度的构造应力，并研究活动褶皱冲断带中的无震和地震断层如何随深度运动。这些联合地表变形和地壳应力分析进一步洞察了褶皱冲断带主滑脱附近的构造应力行为，并表征了主滑脱下的地震潜力。支持该项目的资金由EAR构造和EAR地球物理计划提供。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影响审查标准进行评估，被认为值得支持。

Taiwan is one of the most active tectonic plate boundaries in the world. The high collision rate between the Philippine Sea Plate and the Eurasian Plate has built up a series of hills and mountains called a fold-and-thrust belt in western Taiwan. There have been at least 10 powerful earthquakes in this belt in the last 100 years. Every year, more than 1.6 inches of plate shortening is accommodated by this fold-and-thrust belt, making western Taiwan an ideal natural laboratory for understanding how mountains are built and earthquakes are generated. This three-year proposal supports two tenure-track early career faculty members and a female graduate student to broaden diversity in the Science, Technology, Engineering, and Mathematics (STEM) fields. Some of the products can be integrated into an outreach package for the Maryland Day open house event. This package is designed for the general public for learning active plate tectonics, earthquake cycles, and natural hazard in different tectonic environments. Additionally, this project promotes collaboration between several institutions in the US and Taiwan. The analyses and results of this work are directly relevant to seismic hazard assessment in western Taiwan. The team is merging geodetic and seismologic measurements in order to answer scientific questions such as: (1) What are the characteristics of surface deformation in the fold-and-thrust belt in Taiwan? (2) Is the orientation of the principal crustal shortening consistent at different depths in a fold-and-thrust belt? (3) Can we use seismology, geodesy, and numerical modeling to identify active faults and calculate slip budget in different parts of the fold-and-thrust belts in western Taiwan? The team uses more than 15 years of continuous Global Navigation Satellite Systems (cGNSS) and interferometric synthetic aperture radar (InSAR) displacement in order to estimate three-dimensional surface deformation with about hundred-feet spatial resolution in the Western Foothills in Taiwan. They also take advantage of the high-resolution seismic data from the Taiwanese seismic catalog to compare with GNSS and InSAR measurements. With these measurements combined, they can comprehensively analyze tectonic stress at different depths and investigate how aseismic and seismic fault motions with depth in an active fold-and-thrust belt. These joint surface deformation and crustal stress analyses bring further insights into the behavior of tectonic stress near the main detachment of a fold-and-thrust belt, and characterize earthquake potential below the main detachment.Funding to support this project is provided by the EAR Tectonics and EAR Geophysics Programs.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.