1D Crustal Velocity Model for West-Central Montana
Session: Intermountain West Earthquakes in the Spring of 2020 [Poster]
Type: Poster
Date: 4/20/2021
Presentation Time: 11:30 AM Pacific
Description:
We derive a new 1-D crustal seismic-velocity model for west-central Montana by analyzing seismic-phase arrivals from the M 5.8, 6 July 2017 earthquake that occurred 11 km southeast of Lincoln, Montana, and hundreds of aftershocks that followed over a three-year period (2017-2020). The 2017 Lincoln earthquake was the largest event above M 5.5 to occur in western Montana in over half a century, the last being the 1959 M 7.3 Hebgen Lake earthquake in southwestern Montana. To determine the seismic-velocity model, we manually retrieve continuous seismic data recorded by broadband stations in the University of Montana Seismic Network (UMSN), which have been deployed specifically and strategically to study the Lincoln aftershock sequence, supplemented by telemetered data from the Montana Regional Seismic Network (MRSN). To constrain the model, we invert phase arrivals from several hundred well-recorded earthquakes (>20 phase arrivals) using the software program VELEST. The final model characterizes the crustal seismic-velocity structure as a function of depth, appropriate to an area in western Montana of about 5000 km2.
Developing a new, regional seismic-velocity model advances earthquake science in Montana. The velocity model currently in use to estimate hypocenter locations was last updated in 2003 and is most appropriate for southwestern Montana. Due to western Montana’s proclivity towards infrequent, high-magnitude earthquakes, the 2017 Lincoln event has provided a prime opportunity to collect quality seismic data that will allow us to create a much-needed crustal velocity model for this seismically active region of Montana. This will be the first model derived specifically for the west-central region of the state and will improve the accuracy of hypocenter locations, in addition to enhancing our understanding of the area’s crustal velocity structure and crustal stress conditions.
Presenting Author: Courtenay J. Duzet
Student Presenter: Yes
Authors
Courtenay Duzet Presenting Author Corresponding Author courtenay.duzet@umconnect.umt.edu University of Montana |
Hilary Martens hilary.martens@mso.umt.edu University of Montana |
Michael Stickney mstickney@mtech.edu Montana Technological University |
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1D Crustal Velocity Model for West-Central Montana
Category
Intermountain West Earthquakes in the Spring of 2020