Report on Gorely (Russia) — 9 January-15 January 2008
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 9 January-15 January 2008
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2008. Report on Gorely (Russia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 9 January-15 January 2008. Smithsonian Institution and US Geological Survey.
52.559°N, 158.03°E; summit elev. 1799 m
All times are local (unless otherwise noted)
KVERT reported on 11 January that seismic activity in the area of Gorely and Mutnovsky volcanoes was slightly elevated above background levels during the previous three weeks, but increasing activity was not confirmed. There is only one seismic station in the area of the two volcanoes so the source of the seismicity cannot be determined. Activity was not observed on satellite imagery. The level of Concern Color Code was lowered to Green.
Geologic Background. Gorely volcano consists of five small overlapping stratovolcanoes constructed along a WNW-ESE line within a large 9 x 13.5 km caldera. The caldera formed about 38,000-40,000 years ago accompanied by the eruption of about 100 km3 of tephra. The massive complex includes 11 summit and 30 flank craters, some of which contain acid or freshwater crater lakes; three major rift zones cut the complex. Another Holocene stratovolcano is located on the SW flank. Activity during the Holocene was characterized by frequent mild-to-moderate explosive eruptions along with a half dozen episodes of major lava extrusion. Early Holocene explosive activity, along with lava flows filled in much of the caldera. Quiescent periods became longer between 6000 and 2000 years ago, after which the activity was mainly explosive. About 600-650 years ago intermittent strong explosions and lava flow effusion accompanied frequent mild eruptions. Historical eruptions have consisted of moderate Vulcanian and phreatic explosions.