Hilbert-Huang transform of infrasound for tsunami early warning systems

Abstract

When an earthquake occurs tectonically and volcanically, it is preceded by the emergence of sound wave propagation that cannot be heard by the human ear because it has a low frequency, called infrasound. These infrasound waves are difficult to detect because they are much weaker than earthquake waves and other natural sound waves in nature. The Hilbert-Huang transform method (HHT) is proposed, which in principle decomposes a wave into several simpler sinusoidal harmonic waves so as to separate the low-frequency infrasound waves from the other waves. Once separated, the envelope frequency can be determined which represents the frequency of the earthquake occurrence, then the amplitude represents the predicted earthquake strength, and the wave propagation phase that represents the location of the earthquake source. From the comparison of secondary data, it was obtained that HHT was able to obtain all three information faster than the data from seismographs so that it had the potential to increase the evacuation time which in turn reduced the potential for greater casualties and losses.