Algorithms for automatic, real-time tsunami detection in wind-wave measurements: Using strategies and practical aspects

The present paper concentrates on the actual use - in the framework of a Tsunami Early Warning System - of the algorithms to be implemented in the software of wind-wave gages in order to automatically perform the real-time detection of tsunamis within recorded signals. Focus is on the amplitude-discriminating algorithm, mainly based on an infinite impulse response time domain filter, proposed by the authors in a previous paper. In particular, the problems that may arise in filtering out ‘disturbances’ such as long tidal waves are addressed, and an original method to perform the full characterization of the waveform of an actually detected tsunami, automatically and in ‘quasi’ real-time is proposed. Tests were carried out using time-series resulting from the superposition of actual tsunami signals recorded by some of the tsunamometers of the Deep-ocean Assessment and Reporting of Tsunamis program, and different wind-wave signals synthesized by means of the random-phase method. In particular, the tsunamometers’ records collected during the events triggered by the earthquakes occurred off the coast of Chile on February 27, 2010, and off the Pacific Coast of Tohoku (Japan) on March 11, 2011, were used. The results show that the overall detection and characterization of a tsunami can be effectively carried out, automatically and in real-time, using the proposed new algorithm.