Real-time capability of meteotsunami detection by WERA ocean radar system

Abstract

High-frequency (HF) ocean radar systems have demonstrated their capability to capture the signal from tsunami currents after the 2011 Tohoku earthquake and tsunami. However, these systems were configured for mapping surface currents in the coastal zones and not for detecting specific patterns of tsunami waves in real-time. The WERA® ocean radar system was optimized for tsunami alerting and installed for real-time tsunami monitoring at the coast of Tofino, British Columbia, Canada. If the shelf extends tens of kilometers off the coast then the first appearance of tsunami waves can be monitored early enough to issue an alert message. On 14 October 2016, the WERA system detected strong changes in measured radial currents at distances up to 60 km off the coast and triggered an alert immediately. The system tracked the unusual current pattern in real-time following the wave propagation coincided with an atmospheric cold frontal passage. No earthquake occurred at that time but strong storm currents caused most likely by remnants of typhoon Songda were the most likely reason for the detection. This localized event seems to be the combination of the strong currents caused by the typhoon, the storm surge, and a large wave that could be classified as a meteorological tsunami (meteotsunami). This detection showed the capability of the radar to measure unusual surface current velocities induced by tsunami waves. The real-time detection and alerting on this tsunami-like current have shown a good applicability of HF phased-array radar technology for offshore tsunami monitoring and navigation safety.