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Imaging Shallow S-Wave Structure Using Telecom Fiber-Optic Cable in Urban Areas

Session: Recent Development in Ultra-Dense Seismic Arrays with Nodes and Distributed Acoustic Sensing [Poster]

Type: Poster

Date: 4/20/2021

Presentation Time: 04:15 PM Pacific

Description: 

Surface wave signal extracted from the continuous ambient noise recorded by the DAS with fiber-optic buried in shallow trenches has been widely employed to construct S-wave velocity structure. DAS is easy to incorporate with existing cable (dark fiber) that significantly reduces deployment costs in urban areas. We investigated the shallow structure along a 5.2-km long telecom fiber-optic cable in a city with DAS continuous ambient noise.This DAS array includes two segments along Taihe Rd. and Jinniu Rd, which the traffic activities are significantly different. The 2D shear-wave velocity profile beneath the Taihe Rd was successfully construted with the 1-10 Hz Rayleigh wave signals emerged on the noise cross-correlation functions. The obtained velocity model explains the HVSR curves computed with collocated 3C geophone data. However, the direct Rayleigh wave signal is contaminated by the precursory signals on NCFs of channels along the Jinniu Rd. A series of synthetic tests were designed to analyze precursory signals and weak direct surface wave sginal. The result suggests that the imhomogeous noise distribution produces such precursory signals. The various coupling also contributes to the insufficient direct surface wave signal extraction.

Presenting Author: Zhenghong Song

Student Presenter: Yes

Authors