Nonlinear Earthquake Response of Marine Sediments With Distributed Acoustic Sensing
Abstract
Soft sediment layers can significantly amplify seismic waves from earthquakes. Large dynamic strains can trigger a nonlinear response of shallow soils with low strength, which is characterized by a shift of resonance frequencies, ground motion deamplification, and in some cases, soil liquefaction. We investigate the response of marine sediments during earthquake ground motions recorded along a fiber‐optic cable offshore the Tohoku region, Japan, with distributed acoustic sensing (DAS). We compute AutoCorrelation Functions (ACFs) of the ground motions from 105 earthquakes in different frequency bands. We detect time delays in the ACF waveforms that are converted to relative velocity changes (dv/v).dv/vdrops, which characterize soil nonlinearity, are observed during the strongest ground motions and exhibit a large variability along the cable. This study demonstrates that DAS can be used to infer the dynamic properties of the shallow Earth with an unprecedented spatial resolution.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Nov 02, 2022
- Source ID
- 10.1029/2022gl100122
Entities
People
- Kiwamu Nishida
- Loïc Viens
- Luis Fabian Bonilla
- Masanao Shinohara
- Tomoaki Yamada
- Zack Spica
Organizations
- Air Force Research Laboratory
- National Science Foundation
- University of Michigan
- University of Tokyo