FRACTAL STRUCTURE OF THE LITHOSPHERE BASED ON THE CODAS OF LOCAL EARTHQUAKES AND THE SEISMICITY STRUCTURE OF THE RACHA EARTHQUAKE SOURCE

Abstract

Seismic wave scattering can be used to estimate the fractal structure of the lithosphere. We analyzed the digital seismograms of the aftershocks of the magnitude 6.9 Racha, Caucasus, earthquake of April 29, 1991, at epicentral distances of within 50 km from stations of the local seismograph network. An analysis of the frequency-dependent Q-factor of the coda gave estimates for the fractal dimensions of a system of scattering inhomogeneities. It was found that these dimensions were close to the correlation dimensions of background seismicity and is greater than the dimension of active faults by one. The fractal dimension of transient aftershock seismicity decrease with time returning to a value which is close to the fractal dimension of the system of lithospheric inhomogeneities.