Design of an embedded system for the detection of tsunami

Abstract

The embedded system is required for the Deep-ocean Assessment and Reporting of Tsunamis (DART). Each Deep-ocean Assessment and Reporting of Tsunamis (DART) gage is designed to detect and report tsunamis on its own, without instructions from land. The function is achieved with the help of a tsunami detection algorithm. The tsunami detection algorithm in the gage's software works by first estimating the amplitudes of the pressure fluctuations within the tsunami frequency band and then testing these amplitudes against a threshold value. This algorithm is based on bottom pressure recording(BPR). There are other algorithms based on tidal gauges (TG) and Wind wave gauges (WWG).

The amplitudes in the DART algorithm are computed by subtracting predicted pressures from the observed pressures to obtain a filtered signal, in which the predictions closely match the tides and lower frequency fluctuations. The predictions are updated at every 15 seconds, which is the sampling period of the DART gages. Therefore in one hour we get 240 samples. Background oceanic noise determines the minimum detection threshold.

Based on past observations, a reasonable threshold for the North Pacific is 3 cm (or 30 mm). If the amplitudes exceed the threshold value, the tsunametergoes into a rapid reporting mode,also known as event mode, to provide detailed information about the tsunami. It remains in this mode for at least four hours.