MECHANISM OF PERIODIC EXPLOSIONS AS INDICATED BY LABORATORY MODELING

Abstract

The eruptions typical of andesite volcanoes are explosive. The driving force for such explosions is gas at high temperature and pressure, which forms a separate phase that accumulates near the top of the volcanic vent (the 'gas cap') after it is liberated from the volatiles-saturated magmas as the pressure on the system is relieved (flashing off of the magma). It has been observed that explosions accompany the eruption process with a rather pronounced periodicity. The problem of the mechanism of periodic explosions in reality reduces to the problem of the causes or mechanisms generating the lava plug in the short time intervals between explosions. To solve this problem, the authors performed a series of experiments simulating the flashing off of an andesitic melt. Using the above experimental results and observations on actual volcanoes, an explanation of the mechanism of periodic explosions is given. Study materials, methods and results are discussed.