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Characterization of the 2020 Mw 5.7 Magna, Utah Seismic Sequence Full Wavefield Decay

Description: 

On March 18, 2020, an M5.7 earthquake occurred in Magna, Utah; the event struck a populated, urban area which raised the concerns of aftershocks. An aftershock forecast was provided by the USGS and the University of Utah Seismic Network (UUSS) using the earthquake catalogue. This study was conducted to observe and analyze the full wavefield of the aftershock sequence to see if it followed an Omori-Utsu Law-like trend. The RMS ground motion displacements were derived using the SeismoRMS python code of (Lecocq, et al., 2020) from Power Spectral Densities recorded by the UUSS stations located around the epicenter. An Omori-Utsu Law-like noise decay was observed at frequency bands of 4.0-14.0Hz and 4.0-20.0Hz at the stations located within 40km from the epicenter, as well as at a station located 113km away. The observations presented here indicate that the full wavefield may be used as a Omori-Utsu proxy at local seismic stations, but may have limitations due to the impacts of cultural noise as well as local geologic structures that influence the propagation of the seismic wavefield. The data collected in this study will be combined with data from other locales to see if the observable trend is endemic across all significant earthquake events irrespective of magnitude or tectonic setting. Ultimately the goal is to develop constitutive equations that may potentially provide an avenue for the development aftershock forecasts that do not rely on earthquake catalogue completeness or a network of seismic stations.

Session: Earthquake Source Parameters: Theory, Observations and Interpretations [Poster]

Type: Poster

Date: 4/18/2023

Presentation Time: 08:00 AM (local time)

Presenting Author: Kimberly M. Trahan

Student Presenter: Yes

Invited Presentation: 

Authors