Characterization of the Southwestern Puerto Rico Seismic Sequence Full Wavefield Decay
Description:
The 2020 Southwestern Puerto Rico Seismic Sequence (SWPRSS) started on December 28, 2019,with foreshocks that led to the magnitude 6.4 event on January 7, 2020. Thousands ofaftershocks followed, but many of these were not recorded in official catalogs in real time due tooperational or network geometry constraints. This research aims to characterize the full wavefielddecay produced by the 2020 SWPRSS by calculating the RMS ground motion displacements of thepower spectral densities using the SeismoRMS code of (Lecocq et al., 2020) for Puerto RicoSeismic Network and USGS seismic stations on the Island. The ground displacements for stationsin SW Puerto Rico exhibit an Omori-Utsu-like behavior. Here we aim to establish a set of boundaryconditions, including epicentral distance, channel type, and frequency to observe the full wavefielddecay. The displacements show stronger Omori-Utsu-like behavior in the stations closest to theepicenter, but it is still observable in stations that are over 100 km from the epicenter. The Omori-Utsu-like behavior is observable regardless of channel type (BH?, HH?, and EH?) and is observableon both broadband and short-period instruments. The signal is observable in frequency bands4.0–14.0 Hz, 4.0–20.0 Hz, 1.0–20.0 Hz, but it is best shown in the band range of 4.0 Hz–14.0 Hz.The signal is not observable in the frequency band 0.1–1.0 Hz which is expected as a signalproduced by local aftershocks should be constrained to frequencies above this band. If this signalis Omori-Utsu-like, related to aftershocks, and endemic across other aftershock sequences, itcould lead to a new method that would decouple aftershock forecasts from the earthquakecatalog. Further developments of this study have been carried out for the 2019 Ridgecrest,California and 2020 Magna, Utah earthquake sequences in order to confirm the endemic nature ofthis behavior, and have held similar results.
Session: Earthquake Source Parameters: Theory, Observations and Interpretations [Poster]
Type: Poster
Date: 4/18/2023
Presentation Time: 08:00 AM (local time)
Presenting Author: Coralis D. Friedman-Álvarez
Student Presenter: Yes
Invited Presentation:
Authors
Coralis Friedman-Álvarez Presenting Author Corresponding Author coralis.friedman@upr.edu University of Puerto Rico, Mayagüez |
Elizabeth Vanacore elizabeth.vanacore@upr.edu University of Puerto Rico, Mayagüez |
|
|
|
|
|
|
|
Characterization of the Southwestern Puerto Rico Seismic Sequence Full Wavefield Decay
Category
General Session