METHOD FOR DETERMINING TSUNAMI HAZARD Russian patent published in 2020 - IPC G01V1/38 G01V9/00 G01V11/00 

FIELD: physics.

SUBSTANCE: invention relates to methods of seismic microzoning and can be used to detect the possibility of catastrophic events. According to the disclosed method, the analysed and reference observation points are placed on sections with different engineering-geological conditions. Seismic vibrations from earthquakes from potentially dangerous and other focal zones are recorded at said observation points. Dynamic parameters of seismic vibrations and their variations on each of the investigated observation points relative references in a given frequency range are determined. Further, three-component detection of seismic vibrations is carried out on profile network which is orthogonal and directed on the potentially dangerous focal zones. Ocean-bottom seismographs with broadband 0.003–20 Hz seismic channels are also placed on the continental slope and shelf along foot of the continental slope. Said seismographs are used to record tsunami wave pressure at the bottom at frequencies of 0.003–0.01 Hz. Recorded signals are transmitted over a hydroacoustic communication channel to reference points. At places where the ocean-bottom seismographs are installed, time variations of the geomagnetic field are also determined by measuring parameters of the gravitational and magnetic fields. Additionally, tidal oscillations of the sea surface are recorded by measuring wave height and direction with subsequent calculation of phase velocities of waves moving from the epicentre of the underwater earthquake towards the coast for different types of wave motions, wherein external forces of tidal potential, variable atmospheric pressure of wind intensity field and hydrostatic pressure are taken into account along the wave propagation path. According to linear scales sea bottom motions recorded by means of quartz sensors at deep seismic stations determine sizes of generating wave changes by initial parameters and/or interpolation-difference method. Measurements of wave height and direction with subsequent calculation of phase velocities of waves in open ocean are performed by standard radio altimeters installed on flight aircrafts. Tsunami wave forecast is made based on two isolated solitary waves in the form of hills following one after another with a period of oscillations from 15 to 60 minutes, and inclination values for selected waves, wherein if values of inclinations for 2–3 cycles exceed 4–5 ang. sec, then said wave is defined as tsunami wave. On the reference points, the Love and Rayleigh waves are selected, from which free gravity waves are determined by increasing the spectral density when approaching the shore in the low-frequency region, which serve as a signal on the approach of tsunamis. At the reference points, the ocean level variations are also simulated, caused by atmospheric disturbances with the tsunami signal on the shelf taking into account the inhomogeneous shoreline and in open ocean against background of natural long-wave noise with separation of long waves, for which there is a resonance reflection effect, including solitary waves in the form of hills with period of oscillations from 15 to 60 minutes.

EFFECT: technical result is broader functional capabilities.

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