Two powerful eruptions of Quizapu vent on Cerro Azul Volcano, Chile are used as examples to discuss the problem of effusive eruptions of magmas having high preeruptive volatile concentrations. A physicochemical mechanism is proposed for magma degassing, with the volatiles being lost before coming to the surface.
The model is based on the interaction of magmas residing in chambers at different depths and on the difference between the solubility of water in the melt and the water equilibrium concentration in a magma body having a considerable vertical extent. The shallower chamber can accumulate the volatiles released from the magma that is supplied from the deeper chamber. An explanation is provided of the dramatic differences in the character of the 1846–1847 and 1932 eruptions, which had identical chemical–petrographic magma compositions.

Three stages of study of active and potentially active volcanoes on Kamchatka and the Kurile Islands were distinguished: the anterior stage (1700-1935), the new stage (1935-1962) and the recent stage (from 1962 till present time).
This paper provides a new, for the first time scientifically based term of «active volcano». Updated catalogues display active and potentially active volcanoes of Kamchatka and the Kurile Islands. Here we propose a long-term forecast of behavior and parameters of impending eruptions and related volcanic hazards for the typical volcanoes of the 1st and the 2nd stages of evolution.

The paper presents data on identified and described short-term local (1955−1976) enhanced volcanic activity within the Northern Group at the Central Kamchatka Depression and regional disasters (1907-1976), clearly revealed within Kamchatka Peninsular and the Kurile Islands. In scale (volume is about 9 km3, weight of erupted and replaced productswas calculated to be about 16×109 t), the local volcanic disaster was the most powerful in Kamchatka and Kurile Islands over the period of the last 2000 years. This volume exceeds 80% of ~19×109 t totally erupted by all volcanoes over the same period of time. Over the period 1907−1976, the Kamchatka and Kurile volcanoes erupted and transported about 29.5×109 t of juvenile and resurgent material while other volcanoes in the world erupted about 122×109 t.

We have identified, and describe in this paper, a phase of multifactor natural catastrophism that has been the greatest during our era in Kamchatka, to be dated 0-650 A. D. Its chief components were. The last catastrophic eruptions to have occurred (a caldera-generating one at about 240 A. D., the pyroclastics volume being 18-19 km3 and a subcaldera one around 600 A. D. with the volume of lava and pyroclastics 9.5-10.5 km3) which were followed by irreversible relief changes over areas of hundreds of square kilometers and have affected rather injuriously many other environmental components. An exceptionally intensive activity of the other volcanoes (at least 75-80% of all active and potebtially active Kamchatkan volcanoes were erupting, tens of large and catastrophic eruptions occurred). Regional catastrophic and large ashfalls. A sharp, large-amplitude (between 1.5-2 and 12-15 m) tectonic uplift of various blocks in Kamchatka. Large earthquakes accompanied by large-volume rockfalls, landslides, large and frequent tsunamis. The catastrophic events of that time are argued to have been part of a worldwide phase of natural catastrophism that we hypothesize to have occurred at the beginning of our era.