Velocitymodel of the Hronov-Po?í?í Fault Zone from Rayleigh wave dispersion

摘要

The Hronov-Po?í?í Fault Zone (HPFZ) is an active tectonic area with regularly occurring shallow earthquakes up tomagnitude 5. For their exact locations, at least an average velocity model of the area is needed. A method of measuring local phase velocities of surface waves using the array of stations deployed permanently in the HPFZ is introduced. Seven regional and teleseismic events are selected to represent different backazimuths of propagation. Applicable range of periods is estimated for each event. The coherency of the waves reaching the array is constraining the short period range. The dimension of the array is a limiting factor for the long-periods. A dispersion curve of Rayleigh wave phase velocity measured at the vertical component and characterizing 1D properties of the target area is determined using the seven measurements for the interval from 1 to 40 s. An isometric method is used to invert the determined dispersion curve for shear and longitudinal velocity distribution from the surface to the depth of 65 km.