Multiple-Scale Seismic Imaging Based on Distributed Acoustic Sensing and Ambient Noise Interferometry
Session: Fiber-Optic Seismology II
Type: Oral
Date: 4/23/2021
Presentation Time: 02:15 PM Pacific
Description:
Ambient noise interferometry techniques have been demonstrated to be a powerful tool to characterize multiple scales of earth structure with examples ranging from global earth structure to near-surface soil characterization. However, sparse observation networks often limit the spatial resolution of ambient noise studies for near-surface characterization as well as for highly localized features such as small fault systems. Distributed Acoustic Sensing (DAS) is a recently developed technique which utilizes fiber optical cables to measure dynamic strain at the meter scale. DAS enables seismic observations with an intriguing combination of broad frequency band (from mHz to kHz), large spatial coverage (tens of km) and fine spatial sampling (1 m), which is typically unavailable with conventional sensors at moderate costs.
We present a case study of using DAS and ambient noise interferometry for multiple-scale seismic imaging with an unlit fiber-optic telecommunication infrastructure (dark fiber) in Imperial Valley, California. The study utilizes passive DAS data acquired from early November 2020 over a 27km section of dark fiber from Calipatria, CA to Imperial, CA. We apply ambient noise interferometry to retrieve coherent signals from DAS records, and high-quality surface waves as well as body waves are observed. We demonstrate a new roll-along strategy for surface wave imaging which utilizes localized supergathers to improve signal-to-noise levels for the fundamental and higher order modes. As a result, we are able to obtain high-resolution S wave velocity (Vs) structure to ~800m depth and an averaged S wave velocity structure to close to 2 km. Ambient noise autocorrelation imaging provides consistent results and has assisted in resolving sharp lateral contrasts in subsurface properties. Our results provide improved constraints on subsurface features in the Imperial Valley and provide some hints concerning structures related to the Brawely Seismic Zone.
Presenting Author: Feng Cheng
Student Presenter: No
Authors
Feng Cheng Presenting Author Corresponding Author marscfeng@rice.edu Rice University |
Veronica Rodriguez Tribaldos vrodrigueztribaldos@lbl.gov Lawrence Berkeley National Laboratory |
Benxin Chi benxin.chi@rice.edu Rice University |
Avinash Nayak anayak7@lbl.gov Lawrence Berkeley National Laboratory |
Michelle Robertson mcrobertson@lbl.gov Lawrence Berkeley National Laboratory |
Todd Wood tjwood@lbl.gov Lawrence Berkeley National Laboratory |
Robert Mellors rmellors@ucsd.edu University of California San Diego |
Patrick Dobson pfdobson@lbl.gov Lawrence Berkeley National Laboratory |
Jonathan Ajo-Franklin ja62@rice.edu Rice University |
Multiple-Scale Seismic Imaging Based on Distributed Acoustic Sensing and Ambient Noise Interferometry
Category
Fiber-optic Seismology