Overview
- The Japan Meteorological Agency will begin operational use at noon on November 20, 2025, after completing quality checks of the coastal system.
- Eighteen new tsunami gauges on the seafloor from offshore Kochi to Hyuga‑Nada will feed real-time data to warnings.
- Detection could occur up to about 10 minutes earlier using the coastal system alone, and up to about 20 minutes earlier when combined with the offshore network.
- Published offshore tsunami observation points will increase from 250 to 268 as the coastal sensors are integrated.
- NIED built N‑net to reduce Nankai Trough disaster risk, with the offshore system already in operational use since November 21, 2024.