RAPID: Quantifying Post-Seismic Crustal Deformation in Southwestern Puerto Rico

University Of Puerto Rico Mayaguez, Mayaguez PR

Investigators

Abstract

This RAPID project intends to collect GPS data in the immediate aftermath of the Puerto Rico earthquake sequence that included the January 7, 2020 magnitude 6.4 mainshock. This is the largest earthquake recorded in the region since 1918. Understanding key aspects of the tectonic and seismic processes in the area will be critical to placing this recent earthquake swarm into context. Three decades of monitoring using GPS has revealed that the southwestern part of Puerto Rico is moving independently from the rest of the island. This work will add to the understanding of how the island is deforming before and after the earthquake sequence in addition to understanding earthquake displacements. The project supports a Hispanic-Serving Institution, and includes significant outreach to the local community related to these seismic events. Since December 29, 2020,the southwestern region of the Puerto Rico-Virgin Islands microplate has been hit by an extensive earthquake swarm, with several magnitude 5 earthquakes and a mainshock of 6.4 that occurred on January 7, 2020. The region has seen significant devestation, a displaced population and anxiety with the continued sequence. Several faults have been identified in the region. However, the most probable causative fault has been recently discovered, the North Boqueron-Punta Montalva fault. Instrumenting the fault is critical to assess seismic and tsunami risk in the region. This project will re-measure all 18 campaign GPS sites in the PRVI tectonic block and install 6 temporary real-time GNSS sites. The goal is to quantify the motion of the southwestern Puerto Rico block and understand which faults are accommodating motion. The geodetic data that is collected will help researchers to estimate how the recent seismic activity is associated with elastic strain accumulation on the landward extension of the fault. 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.