Dynamics of Magmatic Flow and Compressional Waves in Magma

The dynamics of magmatic melts in the near-surface part of several kilometers depth is determined by gas release processes. Formation of free gas share is an energy source, while decreasing of the density of the melt creates conditions for magma motion to the Earth's surface. As the water content in the total volume of gas is about 80% for magmatic basaltic melts, gas release of water in the near-surface part of the magmatic column realizes the main share of energy, which leads to volcanic bursts and continuous gas-ash flows throughout the eruption process. Gas release processes create pressure variations in magmatic melts, and these variations are transferred into the solid medium as elastic oscillations forming seismic waves. The principal frequency of seismic signals for active volcanoes is several hertz, and the presence of spectral peaks has been explained by the presence of resonant sources.