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Preliminary Shallow Seismic Imaging at Los Alamos National Laboratory Using Distributed Acoustic Sensing

Description: 

The characterization of near-surface geology is crucial for assessing seismic hazards and monitoring transient signals. Distributed acoustic sensing (DAS) has proven to be an effective tool for generating the high-resolution imaging needed for detailed near-surface studies. In this work, we examine the challenges of using DAS for shallow imaging in the highly attenuative geologic environment at Los Alamos National Laboratory (LANL). LANL is located on the eastern edge of the Valles Caldera in northern New Mexico, USA, a caldera formed by two major eruptions approximately 1.6 and 1.2 million years ago, which produced ~330 m thick units of tuff on which the lab presently resides on. The tuff’s high seismic attenuation has made it difficult to accurately image subsurface fault structure, with many previous active seismic surveys yielding limited results. In this study we use data from two DAS interrogators, a Silixa iDAS v2 and Terra15 Treble+, deployed on 5.6 km of dark fiber at LANL in 2024 to compute dispersion curves from ambient noise cross-correlated channels along the fiber. Preliminary findings reveal robust cross-correlation functions along approximately 4 km of the fiber at frequencies of 1 to 25 Hz. The interrogators record data in different units, strain rate (Silixa iDAS v2) and velocity (Terra15 Treble+) allowing for us to assess the impact on our dispersion analysis.

Session: Fiber-optic Sensing Applications in Seismology [Poster]

Type: Poster

Date: 4/15/2025

Presentation Time: 08:00 AM (local time)

Presenting Author: Emily

Student Presenter: No

Invited Presentation: 

Poster Number: 60

Authors