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

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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.