A Detailed View of the 2020-2021 Southwestern Puerto Rico Seismic Sequence With Deep Learning
Description:
The still-ongoing 2020-2021 southwestern Puerto Rico seismic sequence is remarkable for its multiple-fault rupture complexity and unusually high aftershock productivity. We applied an automatic workflow to continuous data from 42 seismic stations to build an enhanced earthquake catalog with ~140,000 events for the 2+ year sequence, from 2019-12-28 to 2022-01-01. This workflow included the EQTransformer deep learning model for event detection and phase picking, the EikoNet-HypoSVI probabilistic earthquake location approach with a neural network trained to solve the eikonal wave equation, and relocation with event-pair waveform cross-correlation. EQTransformer increased the number of catalog events in the sequence by ~7 times; EikoNet-HypoSVI event location improved depth estimates. The enhanced catalog revealed how the sequence evolved on a complex system of many small normal and strike-slip faults. This sequence started on 2019-12-28 with a M4.7 strike-slip earthquake, followed by shallow strike-slip M5+ foreshocks in a compact region. The oblique normal-fault M6.4 mainshock then happened on 2020-01-07. Early aftershocks in January 2020, including several M5+ earthquakes, quickly expanded into two intersecting wide fault zones with diffuse seismicity: one extending ~35-km on a northward-dipping normal fault, the other ~60-km-long and oriented WNW-ESE on strike-slip faults. Later aftershocks moved westward, deeper, and to outer reaches of the active fault zones; abrupt rapid seismicity migration followed larger M4.7+ aftershocks in May, July, and December 2020. The observed seismicity space-time evolution indicates cascading failure of stress transfer on multiple critically stressed faults. The high aftershock productivity results from the complex multiple-fault network hosting the sequence, which is characteristic of an immature fault system in the diffuse deformation zone around Puerto Rico at the North American-Caribbean plate boundary region.
Session: The 2020-2021 Southwest Puerto Rico Seismic Sequence: Current State of Knowledge and Implications
Type: Oral
Date: 4/18/2023
Presentation Time: 08:00 AM (local time)
Presenting Author: Clara E. Yoon
Student Presenter: No
Invited Presentation:
Authors
Clara Yoon Presenting Author Corresponding Author cyoon@usgs.gov U.S. Geological Survey |
Elizabeth Cochran ecochran@usgs.gov U.S. Geological Survey |
Elizabeth Vanacore elizabeth.vanacore@upr.edu University of Puerto Rico Mayagüez, Puerto Rico Seismic Network |
Victor Huerfano victor.huerfano@upr.edu University of Puerto Rico Mayagüez, Puerto Rico Seismic Network |
Gisela Báez-Sánchez gisela.baez1@upr.edu University of Puerto Rico Mayagüez, Puerto Rico Seismic Network |
Jack Wilding jwilding@caltech.edu California Institute of Technology |
Jonathan Smith jon_smith83@hotmail.co.uk California Institute of Technology |
|
|
A Detailed View of the 2020-2021 Southwestern Puerto Rico Seismic Sequence With Deep Learning
Category
The 2020-2021 Southwest Puerto Rico Seismic Sequence: Current State of Knowledge and Implications