Ambient Noise Tomography of the Near Surface Using the Ridgecrest DAS Array

Session: Recent Development in Ultra-Dense Seismic Arrays With Nodes and Distributed Acoustic Sensing (DAS) [Poster]
Type: Poster
Date: 4/30/2020
Time: 08:00 AM
Room: Ballroom
Description: 

Near-surface geologic structure is of great interest because of its relationship to groundwater, infrastructure, human activities and seismic hazards. However, the near surface often has vertical and lateral heterogeneities over very small distances that can only be resolved by dense profiles of high-frequency data. Here we demonstrate that surface wave tomography using ubiquitous and continuous ambient noise recorded by Distributed Acoustic Sensing (DAS) arrays can provide high-resolution images of the shallow subsurface.

After the Ridgecrest M7.1 earthquake in early July 2019, we deployed four DAS arrays in the epicentral and surrounding regions. Here we apply ambient noise tomography to the linear DAS array in the Ridgecrest city, with 1250 channels in 10 km. Our preliminary phase velocity profile shows notable lateral variation of shear-wave velocity along the array, even though the entire profile is within the basin. The lateral variations may reflect complex basin geometry and sedimentation history. This new near-surface velocity model will improve our understanding of shaking intensity in this region during the Ridgecrest sequence.

Presenting Author: Yan Yang

Authors