| Abstract: | During the large explosions of the Bezymianny (1956), Shiveluch (1964) and Mount St. Helens (1980) volcanoes, 4.8·1012, 3.0·1012 and 8.2·1012 kg of resurgent and magmatic material were ejected respectively. The eruptions were preceded and accompanied by significant crustal deformations and by a great number of volcanic earthquakes. In all three cases, earthquakes with an energy of E = 109 J occurred 8–11 days before the eruption; their foci were at a distance of less than 5 km from the floor of the active crater and the power of earthquake swarms increased continuously and monotonously until the beginning of the eruption. The data obtained on deformations, earthquakes and volcanic activity may be used for the prediction of the place, time, energy and hazards of large explosions of andesitic volcanoes. |
