Report on Koryaksky (Russia) — January 2009
Bulletin of the Global Volcanism Network, vol. 34, no. 1 (January 2009)
Managing Editor: Richard Wunderman.
Koryaksky (Russia) Seismicity, then ash eruptions, after ~ 51-year repose
Please cite this report as:
Global Volcanism Program, 2009. Report on Koryaksky (Russia) (Wunderman, R., ed.). Bulletin of the Global Volcanism Network, 34:1. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN200901-300090.
53.321°N, 158.712°E; summit elev. 3430 m
All times are local (unless otherwise noted)
Koryaksky, which had lacked fumarolic activity during the last ~ 51 years, began steaming after seven months of local seismicity. The increased seismicity became prominent in March 2008 (figure 1) and the first steaming was recorded on 6 October 2008. The first fumarole vent to appear was located at ~ 3 km elevation on the upper NW slope. Koryaksky, a large snow-laden stratovolcano, forms the most prominent feature of the Avachinskaya volcano group. Episodes of elevated seismicity have previously occurred, as reported in December 2003 (BGVN 28:12).
Only two earthquakes struck on 23 December 2008, both at ~ 5 km depth. Observers also heard a booming sound from the volcano at night. NOAA 17 satellite data collected at 2357 UTC on 23 December revealed that a dense ash plume extended over 60 km laterally, and an ash-poor ash plume continued beyond that for another 140 km NE. During 24-25 December observers in the Nalychevo valley saw a dark ash column rise about 200-300 m from the upper NW-flank vent.
On 28 December 2008 moderately explosive vulcanian-type eruptions occurred. Ash plumes rose to ~ 4 km altitude and extend NW. Observers also saw significant fumarolic activity at two vents. During a break in cloud cover on 30-31 December observers saw gas-and-steam plumes, which were thought to contain small amounts of ash. They drifted along the surface of the NW flank, some reaching ~ 4 km altitude. A 2 January KVERT report noted background seismicity during 31 December-6 January, with 1-7 volcanic earthquakes per day and possible episodes of tremor during 30 December to 1 January.
During 6-8 January 2009 strong fumarolic activity continued. According to visual data, gas-steam plumes extended SW from three vents. Gray deposits were visible at the area near the summit. Figures 2 and 3 illustrate the scene on 8 and 10 January 2009. Strong fumarolic activity also prevailed on 14 and 18-19 February 2009.
|Figure 2. Gas and steam escaping from Koryaksky on 8 January 2009. Three vents on the NW slope trace an older fissure. Photo by Alexandr Socorenko.|
|Figure 3. View of Koryaksky looking W from Petropavlovsk on 10 January 2009. The photo was taken from the roof of Institute of Volcanology and Seismology. Photo by Alexandr Socorenko.|
KVERT issued reports on 4 March 2009 noting increased activity, with some ash-bearing plumes extending over 200 km to the NE-ENE on 3-4 March. For the previous week, seismicity was again at background. Ash deposits were identified both on the summit and in the saddle to Avachinsky. At the latter area on 4 March, the deposits reached 1-2 mm thickness.
In a 5 March report, KVERT noted plumes containing small amounts of ash rising to 3.7 km and extending over 220 km. They blew to the ENE, E, and SE on 3-5 March. Koryaksy's N flank contained fresh ash deposits ~ 4.0 cm thick. The crater contained a weak, new fumarole.
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.
Information Contacts: Kamchatka Volcanic Eruptions Response Team (KVERT), Institute of Volcanology and Seismology (IV&S) Far East Division, Russian Academy of Sciences (FED RAS); Kamchatka Branch of the Geophysical Service of the Russian Academy of Sciences (KB GS RAS), Piip Ave. 9, Petropavlovsk-Kamchatsky, 683006, Russia (URL: http://www.kscnet.ru/ivs, http://www.emsd.ru/~ssl/monitoring/main.htm); Alexander Sokorenko, IV&S; Tokyo Volcanic Ash Advisory Center (VAAC), Tokyo, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/).