Report on Koryaksky (Russia) — 26 August-1 September 2009
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
26 August-1 September 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, 26 August-1 September 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 seismic activity from Koryaksky was slightly above background levels during 20-23 August and at background levels during 24-27 August. Ash plumes were seen in satellite imagery drifting more than 385 km in easterly directions. Gas-and-steam plumes containing ash that rose to an altitude of 3.7 km (12,100 ft) a.s.l. were seen drifting in multiple directions during 26-27 August. The Level of Concern Color Code remained at Orange.
Geological Summary. 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.