Local Tomography of the Puerto Rico-Virgin Islands Microplate

Session: Early Results from the 2020 M6.4 Indios, Puerto Rico Earthquake Sequence
Type: Oral
Date: 4/30/2020
Time: 08:30 AM
Room: 115
Description: 

The Puerto Rico-Virgin Island (PRVI) microplate is part of the complex oblique subduction of the North American Plate beneath the Caribbean Plate. Consequently, the microplate is both surrounded and crosscut by significant geomorphological structure and faults systems. To the North lies the Puerto Rico Trench, to the East the Anegada Passage, to the South the Muertos Trough and to the West the Mona Passage. Additionally, major fault systems such as the Great Southern Puerto Rico Fault Zone and the Great Northern Puerto Rico Fault Zone cross-cut the PRVI microplate. The region is quite seismically active as the Puerto Rico Seismic Network locates ~3,500-4,000 earthquakes a year in the PRVI region. The majority of this activity, however, is located north of the islands and is associated with the Puerto Rico Trench creating a challenge for robust tomographic imaging. Due to this non-ideal geometry, resolution in Southern Puerto Rico was limited. However, the recent M6.4 Indios Sequence in southwestern Puerto Rico has provided new earthquake sources to the south of Puerto Rico which can now be included in local tomography. Additionally, 9 new station sites in southwestern Puerto Rico were deployed in January 2020 by the USGS and the Puerto Rico Seismic Network also improving station density in the region. Here local P and S-wave tomography results and earthquake relocations using the LOTOS code will be presented for the region including these new source and receivers from the Indios Sequence in addition to traveltime data recorded by the PRSN for local events from 2010-2017. The inclusion of this new data will help resolve local structures in southern Puerto Rico which were previous not resolved in local tomography due to the lack of sources in the region.

Presenting Author: Elizabeth A. Vanacore

Authors