Report on Koryaksky (Russia) — 12 August-18 August 2009
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 12 August-18 August 2009
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2009. Report on Koryaksky (Russia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 12 August-18 August 2009. Smithsonian Institution and US Geological Survey.
53.321°N, 158.712°E; summit elev. 3430 m
All times are local (unless otherwise noted)
KVERT reported that during 10-12 August seismic activity from Koryaksky was above background levels. On 12 August, an ash plume seen on satellite imagery drifted 180 km ESE at an altitude of 3.5 km (11,500 ft) a.s.l. During 15-16 August seismic activity increased, and seismic tremor was detected. On 16 August, a gas plume with a small amount of ash was seen on satellite imagery drifting 80 km WNW. During 17-18 August, an ash plume rose to an altitude of 4 km (13,100 ft) a.s.l. Ashfall up to 1 mm thick was reported in areas to the SW. The Level of Concern Color Code was raised to Orange.
Geologic Background. The large symmetrical Koryaksky stratovolcano is the most prominent landmark of the NW-trending Avachinskaya volcano group, which towers above Kamchatka's largest city, Petropavlovsk. Erosion has produced a ribbed surface on the eastern flanks of the 3430-m-high volcano; the youngest lava flows are found on the upper W flank and below SE-flank cinder cones. Extensive Holocene lava fields on the western flank were primarily fed by summit vents; those on the SW flank originated from flank vents. Lahars associated with a period of lava effusion from south- and SW-flank fissure vents about 3900-3500 years ago reached Avacha Bay. Only a few moderate explosive eruptions have occurred during historical time, but no strong explosive eruptions have been documented during the Holocene. Koryaksky's first historical eruption, in 1895, also produced a lava flow.