Abstract

On a Resonant Properties of Magma Structures of the Elbrus Volcano

A.L.Sobisevitch, L.Ye.Sobisevitch (Shcmidt Institute of Physics of the Earth, Moscow, Russia); V.K.Milyukov, A.V.Kozyreva (Moscow State University, Moscow, Russia);

e-mail: alex@uipe-ras.scgis.ru

As the geological medium contains inhomogeneities (cavities or inclusions) significantly smaller than a length of a seismic wave, certain local resonant effects were observed upon wave incidence. It has been shown that a cavity in a layered half-space is responsible for reradiation of a secondary wave field. Theoretical study reveals eigen frequencies of oscillations of a cavity, excited by a harmonical wave or a pulse, in a half-space. It has been shown that distant earthquakes may excite eigen oscillations of the magma chamber and the magma source of the Elbrus Volcano. The experimental data on the local low-frequency deformation processes have been collected for about 40 distant earthquakes. After subtraction of the Earth.s eigen frequencies from the experimental spectrums the eigen frequencies of the magma chamber and the magma source of the Elbrus Volcano were determined. The frequency range (70 . 40 s) allows to estimate dimensional properties of the structures studied.

Section : 6