| Description |
Seismic waves traveling through the Earth interact with heterogeneities present at all scales. Primarily, the focus is on travel times associated with coarse scale structures; however, fine-scale structures also influence the travel time for all phases. Simulating wavefields in a medium with heterogeneities at all scales requires a huge amount of computation, posing a significant challenge. Additionally, the distribution of fine-scale heterogeneities not only affects travel times but also impacts how subsurface properties are observed via these travel times. To address these challenges, an upscaling method based on Renormalization Group theory is proposed. This approach aims to generate wave simulations more cost-effectively by reducing the required number of grid points while maintaining the accuracy of the wavefield. Moreover, it will be helpful in analyzing the impact of fine scale structures on coarse scales. The DAS technology transforms a fiber-optic cable into a massive 1C seismic array, recording in-line strain or strain-rate. The distributed optic sensors use optical time-domain reflectometry (OTDR): a series of pulses are transmitted into the fiber by an interrogator, and the Rayleigh backscattered signal is detected, amplified, and digitized. Traditionally, understanding of shallow marine sediments and subduction settings relies on costly active seismic surveys, which have limited global coverage. Therefore, a cost-effective, high-resolution ocean-bottom subsurface S-wave imaging approach is proposed using ocean-bottom Sanriku DAS cable data.
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