It is shown that the young andesite-basaltic cone of Avacha Volcano was more complex, of the "cone-in-cone" type, in the 18th and early 19th century than is now the case. The upper cone was then nested in a crater of diameter 350-400 m, its base being at absolute heights of 2720 m, while the summit crater had a diameter of 50-100 m at absolute heights of 2800-2850 m. Since the summit crater was small, S.P. Krasheninnikov was induced to call Avacha Volcano a "peaked" one in 1738. The major eruption of 27-29 June, 1827 nearly anni-hilated the nested upper cone, while Young Cone of Avacha Volcano acquired nearly the present-day outward shape.

This paper presents results of study of the 2012-2013 Tolbachik fissure eruption on the basis of remote sensing
techniques.
We have calculated values of vertical displacements, lava thickness and the volume of the erupted lava. Values of
vertical displacements were estimated using a series of
radar interferometric pairs for the Tolbachik eruption zone.
These pairs correspond to the concluding phase of the erupti
on, when vertical displacements were relatively small.
Vertical displacements were calculated for parts of lava fields with coherence value over 0,4. The obtained values of
vertical displacement are typical for subsidence caused by cooling lava flows. The maximum value of subsidence is
27 cm for 24 days. The calculation of lava thickness was based on comparison of multitemporal DEMs. Height profiles measured by geodetic GPS receivers during fieldwork in August 2013 were used to estimate the quality of DEMs, derived from satellite imagery: freely available SRTM, SRTM-X, ASTER GDEM and the DEMs calculated at RDC ScanEx from two stereopairs of SPOT6 images (of 18.07.2013 and 11.10.2013). The RMS error for heights of SRTM-X and
SPOT 6 in relation to GPS data is within ±5 m. This enables to estimate the total thickness of new lava fields on the
basis of height differences between SRTM-X and SPOT 6 DEMs. Both SPOT 6 DEMs were used together to eliminate errors caused by clouds and snow. The maximum lava thickness is over 80 m. The volume of the erupted lava is 0,521±0,25 km3.

The paper provides results from application of designed modern computer techniques for interpretation of materials from complex geophysical investigation of submarine volcanoes 2.7 and 2.8, which are located west of the south-western coast of Onekotan Island in the Kurile island arc. The research resulted in estimation of rock magnetic properties in natural deposits and revealed that the south-western flanks of submarine volcano 2.8 are the most magnetized with their productive magnetization of about 2 A/m. The authors suggested that the feeding channels of volcano 2.7 stretch southwest, while the feeding channels of volcano 2.8 stretch subverticaly, southwest and southeast. A peripheral magma chamber of the volcano was revealed at the depth of about 650 m.