YEN-TING KOHo, Kun‐ChiKun‐ChiHoLin, Chun‐HungChun‐HungLinHuang, Hsin‐HuaHsin‐HuaHuangHO-HAN HSUHAO KUO-CHENCheng, Hou‐ShengHou‐ShengChengHuang, Chen‐FenChen‐FenHuangHsu, YaoYaoHsuWu, En‐ShiEn‐ShiWuChen, Hsi‐AnHsi‐AnChenMa, Yu‐FangYu‐FangMaWu, Hung‐YiHung‐YiWuLin, Po‐YinPo‐YinLinChen, Yu‐HsianYu‐HsianChenTien, Wei‐JongWei‐JongTienSiao, Bo‐YuBo‐YuSiaoWu, Hui‐YuHui‐YuWu2026-03-132026-03-132026-02-11https://scholars.lib.ntu.edu.tw/handle/123456789/736315Quantifying how incident ocean waves transfer energy into seismic surface waves along the nearshore is essential for understanding coastal hazards and Earth–ocean coupling, yet time-resolved in situ estimates have been scarce. Here we use a beach-deployed distributed acoustic sensing array co-located with an ocean-bottom node to directly measure the conversion efficiency from wave impacts to Rayleigh-type ground motion at 4–12 Hz. Frequency–wavenumber analysis, beamforming, and local back-projection consistently locate sources along a fixed, wave-breaking coastal segment, while particle-motion ellipticity confirms the Rayleigh character. Calibrating distributed acoustic sensing strain to ground velocity and combining nearshore wave energetics yields an energy-conversion efficiency on the order of 10−6. The efficiency is strongly modulated by tide, with high-tide conditions enhancing coupling even though the source region remains stationary. Our results establish a quantitative benchmark for dynamic ocean-to-Earth energy transfer at the land–sea interface and provide a generalizable framework for coastal monitoring using existing fiber infrastructure.coastal monitoringdistributed acoustic sensingenergy-conversion efficiencyfrequency–wavenumber analysisocean-bottom nodejournal article10.1029/2025gl120302