  This paper considers the formation of the magma volcano chamber and its
eruption due to melting of the matter within the earth crust because of heating
caused by plastic deformation occurring during tectonic movement. The expansion
of matter in the magma chamber which takes place during its heating, leads to
elastic stresses in the solid shell surrounding the magma chamber. The elastic
energy of such stresses can be as high as 10^17 J per 1 km3 of the melt. The
magma flow rate has been assessed according to available data, which agrees
well with the observation data. The mechanism of low-frequency vibrations
produced by the magma chamber is discussed. The vibrations result from the
excess elastic energy formed during melting at the eruption steady stage. The
suggested radiation theory allows evaluating the size of the magma chamber
according to parameters that can be measured. The obtained theoretical
evaluation of the magma chamber size is supported by the available observation
data.
