Understanding how ocean wave energy transfers into the nearshore crust is fundamental for constraining microseism generation mechanisms and assessing coastal hazard impacts. However, direct quantification has long been hindered by the lack of high–temporal-resolution, in-situ observations.
A research team led by Associate Professor Justin Yen-Ting Ko at the Institute of Oceanography, National Taiwan University, deployed a nearshore fiber-optic array at Sizihwan, Kaohsiung, Taiwan. By leveraging Distributed Acoustic Sensing (DAS) technology, the team achieved the first time-resolved, in-situ quantification of this dynamic ocean–solid Earth energy transfer process.
By integrating DAS-derived strain-rate measurements with wave hydrodynamic modeling, the study estimates that the energy conversion efficiency from ocean waves to seismic surface waves (Rayleigh waves) is on the order of 10⁻⁶ to 10⁻⁵. The results further reveal strong tidal modulation of wave–Earth coupling: higher tidal stages significantly enhance coupling efficiency, even when the source region remains localized near breakwaters and shallow sandbars. This indicates that water-level variations alter the interaction among waves, sediments, and coastal structures.
These findings demonstrate the feasibility of using existing submarine telecommunication fiber networks for real-time coastal monitoring. The approach holds significant potential for evaluating coastal erosion, as well as assessing the structural resilience of critical infrastructure such as breakwaters and offshore wind turbine foundations. This work has been published in Geophysical Research Letters:
Ko, J. Y.-T., Ho, K.-C., Lin, C.-H., Huang, H.-H., Hsu, H.-H., Huang, C.-F., et al. (2026). Tide-modulated ocean-to-Earth energy conversion quantified with coastal fiber sensing. Geophysical Research Letters, 53, e2025GL120302.
https://doi.org/10.1029/2025GL120302
Figure 1 | Nearshore fiber-optic DAS experiment and observations of ocean–Earth energy conversion. (A) Location of the nearshore fiber-optic DAS experimental site at Sizihwan, Kaohsiung, Taiwan. (B) Layout of the submarine fiber-optic cable and the distribution of Ocean Bottom Nodes (OBNs). (C) Ten-minute continuous DAS strain-rate record, with the upper-right inset showing a zoomed one-minute window. The records clearly capture the persistent seismic responses generated by ocean waves impacting the coast. (D) Conceptual diagram illustrating how tidal stage and wave height jointly modulate the efficiency of ocean wave energy conversion into seismic signals during wave–coast interactions.
