Проведено исследование роста коровых магматических очагов вулканов за счет плавления вмещающих пород и выноса выплавленного материала в процессе извержений. Проведено качественное и количественное описание процесса роста проточного магматического очага вулкана, подпитываемого магмой либо непрерывно, либо с перерывами. Определены условия, и дана оценка времени, при котором магматический очаг достигает максимальных размеров. Получена оценка длительности пребывания очага в квазистационарном состоянии, когда температура в нем постоянна, а его размеры близки к максимальным. В качестве примера приведены расчеты динамики роста магматического очага вулкана Авачинский на Камчатке.

This paper is concerned with the eruptions that began simultaneously in the Karymsky volcanic center, Kamchatka, in 1996 and associated phenomena. A significant earthquake swarm started occurring there on January 1, 1996 with magnitudes as high as 6.9. A monoton. summit eruption of Karymsky Volcano followed on January 2, which has continued discharging andesite-dacite lava at a rate of 0.8 t/s until March 1997 and later. Basalts were emplaced along a fissure after 28 000 years of repose producing a phreatomagmatic eruption in the Akademia Nauk caldera at pyroclastic discharge rates of over 800 t/s. The distance between the erupting vents is 6 km. Basic tnunamt. waves resulting from underwater explosions and a high tsunami were observed, a new peninsula developed in the caldera lake, the ground surface experienced an extension of more than 2,3 m, and the fresh-water caldera lake of volume 0.47 km3 was transformed into an acid one (pH 3,2). Brief information is provided on the state of the volcanic center by the late 1995, a successful prediction, and the eruptions themselves. We estimate the depth to the pressure center in the primary magma chamber (18,3 ± 0,8 km), the volume of the crustal magma chambers (400 km3), possible dimensions of the emplaced dike in the stronger crustal layers (thickness 0,7 m, length 4700 m). We discuss a likely mechanism for and relations between the observed processes and the eruptions.

Quantitative characteristics are provided for horizontal and vertical ground deformation on Karymsky and Akademia Nauk volcanoes following a large (M = 6.9) earthquake and a swarm of smaller ones in the Karymsky volcanic center and after the start of simultaneous eruptions on the active Karymsky Volcano and a subaquaceous eruption in the Akademia Nauk caldera. The instrumentally measured horizontal extension (as large 2.33 m on a base of 3.6 km) and vertical subsidence and uplift with a total amplitude of 1.5 m are the greatest of all so far recorded on Kamchatkan volcanoes during the period of instrumental observation.

A mathematical model and a method of computation are developed for the flow of magma with temperature-dependent viscosity in the conduit of a volcano. An example involves the following parameters: conduit radius is 10 m, depth to the magma chamber is 30 km, the overpressure, magma temperature and viscosity in the chamber are 20 bars, 1300° C, and 104, Ю5, 106Pa s, respectively. The initial phase of conduit operation lasting less than 10 years is considered. Conditions are determined under which the conduit freezes (stopping the extrusion), a quasistationary behavior sets in (steady flow), and the flow heats the conduit wall intensively.