Multigrid spatially constrained dispersion curve inversion: towards
distributed acoustic sensing surface wave imaging
Abstract
Surface wave methods, commonly applied in diverse fields, encounter
challenges in complex subsurface environments due to limitations
inherent in traditional inversion techniques. Conventional
one-dimensional inversion (1DI), with its reliance on fixed grids and
deterministic linear approaches, often introduces biases, diminishing
lateral resolution. Laterally constrained inversion (LCI) improves
robustness by addressing lateral coherency but falls short in
delineating arbitrary interfaces due to its dependency on fixed grid
models. The advent of Distributed Acoustic Sensing (DAS) technology
offers extensive seismic data, yet its potential for high-resolution
imaging remains underutilized. We introduce a Multigrid Spatially
Constrained Dispersion Curve Inversion (MCI) method to overcome these
challenges, aiming to harness high-resolution DAS surface wave imaging
capabilities. This paper details the MCI scheme, evaluates its efficacy
through synthetic tests, and applies it to a DAS field study in Imperial
Valley, California. Our findings demonstrate a refined,
higher-resolution S-wave velocity model, offering new insights into the
region’s fault system and emphasizing the necessity of improved spatial
resolution in large-scale geophysical studies.