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A Seismic Source and Ground Motion Characterization Model Developed for a Site in Northeast Puerto Rico

Description: 

The island of Puerto Rico is located on the approximately 275-kilometer-wide tectonically active Puerto Rico-Virgin Island microplate, within the plate boundary between the North American and Caribbean Plates. The boundary is complex, and involves opposing subduction zones, accretion, a collision zone, as well as smaller compressional, extensional, and transform fault elements. An updated seismic source characterization (SSC) was developed in 2021 in support of a project in northeast Puerto Rico. Shallow crustal fault sources located both on land and offshore were characterized. A background seismicity source incorporating an earthquake catalog with events through November 2020, and including the January 2020 Indos sequence, was characterized by weighting of uniform areal source and gridded seismicity source zones. Subduction interface events from the Puerto Rico Subduction Zone and Muertos Subduction Zone were modeled as finite faults dipping toward the island from the north and south, respectively. A source extending from a 40- to 130-kilometer depth was also incorporated in the SSC to model subduction intraslab events beneath the island.

An updated ground motion characterization (GMC) model included state-of-practice NGA-West2 Ground Motion Models (GMM) for crustal events and recently released NGA-Subduction GMMs for subduction interface and intraslab event. The crustal GMMs were reviewed against shallow crustal earthquake records from the Indios event for applicability along with a Puerto Rico-specific GMM developed by Motazedian and Atkinson (2005), which was also included in the GMC model. NGA-Subduction GMMs were compared against the established Abrahamson et al. (2016) subduction GMM for the subduction interface and intraslab sources. The significant SCC and GMC model features, comparisons to the USGS (2003) seismic hazard maps, and overall results from this study will be presented.

Session: 2025 Puerto Rico and the U.S. Virgin Islands National Seismic Hazard Model Update

Type: Oral

Date: 4/18/2023

Presentation Time: 05:00 PM (local time)

Presenting Author: Justin Beutel

Student Presenter: No

Invited Presentation: 

Authors