Presentation Type
Poster Presentation
Category
STEM (science, technology, engineering, mathematics)
Abstract/Artist Statement
In seismically active areas with infrequent large-magnitude earthquakes, high-quality seismic data is critical for determining regional seismic velocity models. Here, we present the first 1-D crustal seismic velocity model for west-central Montana, constrained by seismic phase arrivals from the 2017 M 5.8 earthquake that occurred near Lincoln, Montana, and hundreds of aftershocks that followed over a three-year period (2017-2020). The 2017 M 5.8 Lincoln earthquake is the only event >M 5.5 to occur in western Montana in over half a century, with the previous being the 1959 M 7.3 Hebgen Lake earthquake in southwestern Montana. To derive the seismic velocity model, we analyze continuous seismic data recorded by 11 three-component, broadband stations in the University of Montana Seismic Network (UMSN), which we strategically deployed to record the Lincoln aftershock sequence. We also include seismic data from short-period, vertical-component stations in the Montana Regional Seismic Network (MRSN); three temporary three-component, broadband stations deployed by the U.S Geological Survey (USGS); and three three-component, broadband Advanced National Seismic System (ANSS) stations. We manually pick P-wave arrival times from several hundred well-recorded earthquakes using the AQMS Jiggle software and then invert these data for velocity structure using the program VELEST. To effectively constrain the structure of the deeper crust and upper mantle of western Montana as a whole, we also derive an updated velocity model for western Montana based on a regional scale dataset that also includes TA data from 2006 to 2010. This final model characterizes the velocity structure of the crust and uppermost mantle as a function of depth, appropriate to an area in western Montana of about 40,000 km2 (200 km x 200 km). Both the local and regional models improve the accuracy of hypocenter locations and advance understanding of the region’s crustal structure.
Mentor Name
Hilary Martens
Deriving a 1D Seismic Velocity Model for West-Central Montana
UC North Ballroom
In seismically active areas with infrequent large-magnitude earthquakes, high-quality seismic data is critical for determining regional seismic velocity models. Here, we present the first 1-D crustal seismic velocity model for west-central Montana, constrained by seismic phase arrivals from the 2017 M 5.8 earthquake that occurred near Lincoln, Montana, and hundreds of aftershocks that followed over a three-year period (2017-2020). The 2017 M 5.8 Lincoln earthquake is the only event >M 5.5 to occur in western Montana in over half a century, with the previous being the 1959 M 7.3 Hebgen Lake earthquake in southwestern Montana. To derive the seismic velocity model, we analyze continuous seismic data recorded by 11 three-component, broadband stations in the University of Montana Seismic Network (UMSN), which we strategically deployed to record the Lincoln aftershock sequence. We also include seismic data from short-period, vertical-component stations in the Montana Regional Seismic Network (MRSN); three temporary three-component, broadband stations deployed by the U.S Geological Survey (USGS); and three three-component, broadband Advanced National Seismic System (ANSS) stations. We manually pick P-wave arrival times from several hundred well-recorded earthquakes using the AQMS Jiggle software and then invert these data for velocity structure using the program VELEST. To effectively constrain the structure of the deeper crust and upper mantle of western Montana as a whole, we also derive an updated velocity model for western Montana based on a regional scale dataset that also includes TA data from 2006 to 2010. This final model characterizes the velocity structure of the crust and uppermost mantle as a function of depth, appropriate to an area in western Montana of about 40,000 km2 (200 km x 200 km). Both the local and regional models improve the accuracy of hypocenter locations and advance understanding of the region’s crustal structure.