METHOD OF DETERMINING TSUNAMI PRECURSOR Russian patent published in 2012 - IPC G01V1/38 

FIELD: physics.

SUBSTANCE: method of determining a tsunami precursor, involving placing groups of devices for picking up seismic signals at observation depth horizons in the coastal area and at a distance therefrom with the aim of step by step determination of the risk of occurrence of a tsunami, connecting said groups of devices using a communication channel to external stations for receiving and processing seismic signals, picking up seismic signals, in which the detectors are placed on observation depth horizons that a multiples of 25 m, with maximum observation horizon of 100 m, uniformly distributed on the azimuth; seismic signals are picked up with separation of phases of the type PP, S and T; the arrival of a seismic acoustic wave is determined from frequency shift value of the scattered radiation; wherein detectors placed at a distance from the coastal area are used to analyse low-frequency components of the scattered signal, using quasi-harmonic high-frequency ship noise signals as the reference, and detectors placed in the coastal area are used to determine the onset and direction of arrival of seismic waves via narrow-band filtering and spectral analysis of waves; selection of phases of the type PP, S and T is carried out via narrow-band filtering using recursive Butterworth filters. Input filtration is carried out using recursive filters with integral coefficients, and signals with sampling frequency 100 Hz and below are filtered with coefficients in form of floating point numbers; seismic signals are picked up by wide-band bottom seismographs with not less than three seismic channels, wherein signals are analysed by three independent detectors, and the detection signal is generated when alarm signals coincide in at least two of the three channels; spectral analysis is carried out for both volume waves with phases PP and S and Love, Rayleigh and Stonely surface waves, in which to increase accuracy of prediction, seismic signals are picked up ranges 0.003-02 Hz and 0.1-20 Hz; when processing picked up signals, observation time series, having increase during antidamping of frequency and amplitude of vibrations up to the extreme point with subsequent relaxation, are selected. Analysis of extreme points of amplitude is performed for both distributed according to an exponential law and according to a power law.

EFFECT: high reliability and accuracy of predicting a tsunami by detecting microseismic waves.