GPS geodetic infrastructure for natural hazards study in the Puerto Rico and Virgin Islands region

The Puerto Rico and Virgin Islands (PRVI) are located within the complex plate boundary zone between the North American and Caribbean plates. This region faces multiple natural hazards, such as earthquakes, tsunamis, landslides, hurricanes, and flooding. The islands are part of the Greater Antilles island chain, which is one of the earliest places that employed Global Positioning System (GPS) technology in plate tectonics and natural hazards studies. A dense Continuously Operating Reference Stations (CORS) network with 24 permanent GPS stations is currently operated by a joint effort of academic, government, and local land surveying communities. This region has been regarded as one of the densest CORS coverage regions worldwide. This article summarized the current GPS geodetic infrastructure in the PRVI region, which includes three components: a dense CORS network that is open to the public, a stable local reference frame that is updated in time, and sophisticated software packages for GPS data processing that are freely available to the academic and research community. This article focused on establishing a local reference frame, the stable Puerto Rico and Virgin Islands reference frame of 2014 (PRVI14), which is essential for precisely delineating local ground deformation over space and time. Applications of the geodetic infrastructure for precise faulting, landslide, and sea-level monitoring were illustrated in this study. According to this study, the St. Croix Island is moving away from the Puerto Rico and Northern Virgin Islands toward southeast with a steady velocity of 1.7 mm/year; the Lajas Valley in southwestern of Puerto Rico may be experiencing a north–south direction extension (1.5 mm/year) and a minor right-lateral strike slip (0.4 mm/year) with respect to the PRVI14 reference frame; the current absolute sea-level rise rate in the PRVI coastal region is about 1.6–2.0 mm/year.