Strategic offshore deployment of tsunami gauges for rapid warning at critical coastal sites: A case study for a nuclear power plant in Korea

The tsunami generated by the 2024 Noto Peninsula earthquake has highlighted both the persistent threat of offshore seismic events and the limitations of Korea’s current tsunami monitoring systems, particularly for early detection and rapid response. This study aims to enhance tsunami preparedness by proposing optimized offshore deployment locations for early detection instruments, with a focus on the critical site, Hanul Nuclear Power Plant in Korea. Using the tsunami model, we simulated 41 potential tsunami scenarios originating from the western coast of Japan. From the temporal sea surface elevations of tsunamis, two key parameters (i.e., maximum tsunami height and corresponding early detection lead time) were extracted. To quantitatively assess detection effectiveness, we introduce an ‘early detection performance index,’ which enabled identification of the top three optimal locations for each scenario. By synthesizing these results, we propose a minimal yet effective configuration of offshore gauges capable of providing early warning coverage across all scenarios, thereby improving Korea’s tsunami monitoring network and reinforcing the safety of coastal nuclear facilities.