I. A. Larionov, B. M. Shevtsov, A. V. Kuptsov

Institute of Cosmophysical Researches and Radio Wave Propagation FEB RAS

By means of two systems of directed hydrophones, placed in an artificial reservoir and in a lake, observations of hydro-acoustic emission in the frequency range 0.1…10000 Hz are carried out in Kamchatka. It is done for the purpose of investigation of emission characteristics and its changes, corresponding to the last stage of seismic event preparation. It was shown, that geo-acoustic noise is anisotropic, and its intensity increases in the direction of subduction zone, located 150…200 km from the observation point. At the background of noise, strong acoustic anomalies in kilohertz frequency range are registered with tens and hundreds times excess of the sound level. Opportunity of acoustic signals registration directly from the region of seismic event preparation was evaluated. During the four-year period of observations earthquakes with the energetic class more that 11 and with hypocentre, located not more than 200 km away from the registration point, were selected. From the sixty cases under consideration, thirty seismic events were preceded by 9-30-hour intensive high frequency hydro-acoustic anomalies, which had a special signal form and were easily detected. During other time intervals such acoustic anomalies were not observed. The zones of acoustic anomalies audibility were determined.