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Investigating Shallow Subsurface Structure Near Legacy Nuclear Test Sites Using Single Station HVSR

Description: 

We investigate shallow subsurface structure near two legacy nuclear tests on the Nevada National Security Site. In the first analysis, we use open-source continuous seismic data collected from a single line of a temporary array deployed for the Source Physics Experiment Phase I. For the second analysis, we use continuous data collected as part of the active-source FREY experiment to investigate the HADDOCK legacy nuclear test. Shallow subsurface structure is important for understanding seismic site response and detecting subsurface anomalies. In this investigation, we focus on the use of ambient noise-derived horizontal-to-vertical spectral ratios (HVSR) to highlight frequency-dependent site effects, shallow velocity profiles, and total H/V spectral power. HVSR has several advantages, including repeatability, the need for only short periods of data collection, and application to single-station, high frequency measurements, which are particularly sensitive to the shallowest layers. In this comparison, we test the ability of single-station HVSR to measure changes in subsurface structure along a profile, and within an array, near two sites with potential structural features. We examine the correlation between a new method using the integrated spectral power of H/V and traditional resonance and forward modeling-based approaches for H/V ratios. Using these results, we compare the feasibility of these methods for understanding shallow structure using temporary seismic deployments at sites with potential shallow heterogeneities.

SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.

Session: Advancements in Forensic Seismology and Explosion Monitoring [Poster Session]

Type: Poster

Date: 5/2/2024

Presentation Time: 08:00 AM (local time)

Presenting Author: David

Student Presenter: No

Invited Presentation: 

Authors