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A Comparison of High Precision Relocation Methods Applied to the June 2021 Mount Hood, Oregon Sequence

Description: 

High-precision earthquake locations can illuminate seismogenic structures at depth, elucidate the spatial and temporal history of those structures, and can aid in source determination. This is especially important near volcanic centers considering their geological complexity and the significant volcanic hazards. In this study, we compare three approaches to perform high-precision earthquake relocation using our enhanced Mount Hood earthquake catalog to analyze their efficacy in determining locations for low magnitude events and events with few observations, and discuss the generality and scalability of each method. The enhanced earthquake catalog includes the 166 earthquakes located by the Pacific Northwest Seismic Network to routine operations and 1572 detected earthquakes derived from waveform template matching. Since monitoring began in 1979, the June 2021 sequence is both the best recorded and the most seismically productive sequence at Mount Hood. We relocate events using three different methods: absolute (NonLinLoc SSST + Coherence), hierarchical clustering (GrowClust), and double-difference (HypoDD). Across the methods, it is clear there are at least two clusters of earthquakes, a large cluster 1-2 km from the summit to the southeast and a smaller cluster at the summit. Based on our preliminary analysis NonLinLoc SSST + Coherence locations produced precise earthquake locations on par with the relative relocation methods. The fact that this method preserves the absolute location of earthquakes in geographical space is an asset.

Session: It’s All About Relocation, Relocation, Relocation [Poster]

Type: Poster

Date: 4/20/2023

Presentation Time: 08:00 AM (local time)

Presenting Author: Barrett N. Johnson

Student Presenter: Yes

Invited Presentation: 

Authors