Kliuchevskoi Volcano

Kliuchevskoi volcano, also known as Klyuchevskoy or Klyuchevskaya Sopka, is the highest volcano in Kamchatka, rising to 4835 m above sea level. It is part of the Klyuchevskaya Group which includes active Bezymianny and Tolbachik volcanoes, and a number of probably extinct volcanoes including Plosky Sopky (= Ushkovsky), Kamen and Zimina. The Klyuchevskaya Group started to form about 300,000 years ago, covers a 100x55 km ellipsoid area, and has a volume of about 5000 cubic km above sea level. This makes it the largest volcanic group at any island arc or subduction zone.

Kliuchevskoi is relatively young, having largely formed in the last 7000 years, and erupts calc-alkaline high alumina basaltic lavas with approx. 53% silicate. It has been frequently active in recent times with eruptions occurring almost annually . Activity is frequently focussed at the summit crater, where strombolian or weak vulcanian activity may be accompanied by effusion of lava flows which may descend several kilometers down the steep flanks of the conical stratovolcano. However, at least 15 eruptions in the last century have evolved effusion from vents on the shoulder between Kliuchevskoi and older Kamen volcano and more frequently on the E and NE flanks of the volcano. Notably, during the "Bilyukai eruption" in 1938, lava flows from a vent at an altitude of only 1000 m covered an area about 10km long and over 1 km wide on the east flank. Further, in 1932, flows from two vents at 500 m on the NE flank brought lava to within about 5 km of the village of Kliuchi (see e.g. Ozerov, 2000. J. Volc. Geotherm. Res. 95, p.65-79; Fig.2). Flank eruptions at Kliuchevskoi are often, but not always, associated with the formation of cinder cones with heights of up to 200 meters.

View of ash cloud of Kliuchevskoi from Kamchatka River. Typical dense forest is seen beyond river.	Moonlit view of Kliuchevskoi erupting with reflection in Kamchatka River. Plosky massive is to left, Kamen to right.

Ash from summit and steam from melting glacier	Strombolian activity accompanied by lava flow

The volcano is also capable of powerful explosive activity. For example, in October 1994, a 3 week period of increasing activity was essentially concluded by a 10 hour Sub-Plinian phase, resulting in an up to 13 km high ash cloud and accompanied by about pyroclastic flows which swept down the upper flanks of the volcano in essentially all directions. About 10 flow deposits could be distinguished. These were from 2-6 km long, but all less than 100m wide (Ozerov et al. 1997. Volcanol. Seismol. 18(5), p.501-516). The eruption was also accompanied by N and SW-directed lava flows, of which the largest flowed 5 km NNW down the Krestovsky trench. As the lava came into contact with ice, large phreatomagmatic explosions generated ash clouds as high as 7 km, and the meltwater formed lahars which were initially directed through the Krutenkaya and Kirgurich Rivers, eventually overspilling these and flooding the road east of Kliuchi before finally spilling into the Kamchatka River. It is estimated that 0.05 cubic km of ash and lapilli were erupted during the Sub-Plinian phase, leaving deposits 5 cm thick at a sampling site 15 km downwind of the summit, with individual clasts at this location being over 5 cm in diameter.

Other powerful eruptions occurred in 1900, 1926 and 1945. Whilst the 1994 paroxysm marked the end of an eruptive phase, since activity rapidly declined and terminated 1.5 days later, the 1945 event was followed by a month of largely effusive activity.

The active volcanoes of Kamchatka belong to a SW-NE oriented volcanic arc which extends SW encompassing the Kurile Islands. Arc formation is due to northwestward subduction of the Pacific Plate under the Okhotsk and Kamchatka-Okhotsk Blocks (together forming the Okhotsk Microplate) at a rate of about 8 cm per year. The Aleutian Islands represent a further volcanic arc, resulting from northward subduction of the Pacific Plate under the North American Plate. These subduction zones intersect off the coastline of Kamchatka, with the NE-oriented Kamchatka Plate boundary meeting the NW-oriented Western Aleutian Plate boundary at an angle of about 90 degrees. At the Western Aleutian Plate boundary, the Pacific Plate is moving NW-wards, approximately parallel to the plate boundary so that no significant subduction can be taking place.

Analysis of the passage of seismic P- and S-waves during natural earthquakes allows the location of hypocenters linked to subduction of slabs to be detected, and thus the approximate location of the slabs themselves (Koulakov et al. 2011. Russian Geol. Geophys. 52, p.650-667). Subduction of the 70-100 km thick Pacific Plate under the Okhotsk Microplate in the northern Kuriles and southern Kamchatka region is relatively uniform with subduction down to a depth of 900 km detectable in places. The plate is 100 km below the surface as it passes under the E coast of Kamchatka and sinks to a depth of about 200 km, once 150 km inland.

The situation is more complex in northern Kamchatka, where intersection with the Western Aleutian Arc complicates the subduction mechanism. Here, Koulakov detects a subducting slab down to 250-300 km depth which may represent the remains of a now inactive subduction complex. Parts of the stagnant slab may be gradually breaking off. Certainly, there is a gap between the slabs relating to subduction under Kamchatka and the Aleutian Islands.

It is likely that this gap is linked to the highly productive volcanic centers of Klyuchevskaya Group and Shiveluch further north. Levin et al. 2002 (Nature 418, p.763-767) attribute changes in volcanism in north Kamchatka to breaking off of subducting pieces of slab about 5-10 and 2 million years ago. The more recent event is considered responsible for the high productivity of the Klyuchevskaya Group of volcanoes and the presence of adakite ("slab-melt") in the products of Shiveluch, which is also has an unusually high productivity for a subduction zone volcano.

Grey ash cloud rising before high altitude winds blow away	Ash from summit and steam from melting glacier

Steam and ash clouds as wind direction changes	Plume from Kliuchevskoi (4835m) blowing over Kamen (4585m)

The above video shows mild explosive activity accompanied by the generation of a brightly incandescent lava flow, clearly visible in daylight, and what appears to be a zone of sustained rockfall activity which is apparently remobilizing ash on the flank of the volcano.

20 km from Kliuchevskoi summit on plateau	Ash cloud from Kliuchevskoi

Kliuchevskoi erupting	Kliuchevskoi erupting

Ash cloud billowing from summit of Kliuchevskoi, with lava flow and persistent rockfall on the flank. Snow-covered Kamen volcano is on right.

Kliuchevskoi volcano largely erupts high-alumina basaltic (HAB) lavas, but also high-magnesium basaltic lavas from which the HAB lavas may be formed by differentiation (Ozerov, 2000. J. Volc. Geotherm. Res. 95, p.65-79). Lavas from Kliuchevskoi are clearly distinct in composition from those of the adjacent extinct Kamen volcano, although several cinder-lava cones on the W-SW flank of Kamen appear to be related to Kliuchevskoi. Bezymianny lavas on the other hand are closely related to those of Kamen and it is thought that Bezymianny lavas derive from the same source and plumbing system as those previously erupted at Kamen (Churikova et al. 2013. J. Volc. Geotherm. Res. 263, p.3-21). Lavas from Kliuchevskoi are also distinct from those of the plateau on which the volcanoes of the Klyuchevskaya Group lie. This plateau has been described as a large shield volcano with its center under Plosky Sopky. Although compositionally distinct, there are suggestions that there is some correlation between activity in the magmatic systems of Kliuchevskoi and Bezymianny (Koulakov et al. 2013. J. Volc. Geotherm. Res. 263, p.75-91). Based on a form of seismic analysis termed 4D tomography, it is suggested that a common channel in the mantle extending up to a depth of about 25km provides magma for all volcanoes of the Klyuchevskaya Group. Kliuchevskoi is fed via a complex system of reservoirs in the crust at depths of 8-13km and directly under the edifice, whilst it appears that Bezymianny is linked by a single short-lived channel. Due to the respective timing of eruptions at the two volcanoes it is considered possible that there is a link in activity and that filling of the reservoirs under Kliuchevskoi may be linked to opening of the Bezymianny magma channel. Generally, it appears that increased activity at Kliuchevskoi is linked to quiescence at Bezymianny and vica versa. A detailed model of the magmatic plumbing systems underlying the Klyuchevskaya Group was earlier provided by Fedotov et al. (Volcanol Seismol 1, p.3-35, 2010). Based on extensive review of prior publications and on own analysis, Fedotov places the intermediate magma chamber of Kliuchevskoi at a depth of 20-35km, with the peripheral (upper) magma chamber residing at a depth of 3-5km. The volumes of the chambers are estimated at 650 and 100 cubic km, respectively. Influx of magma into the chambers is not constant, so relative pressures and net in-/outflow rates vary and may play a role in determining types of activity. Pressure in the peripheral chamber was for example high in the 1983-1990 period, when numerous flank eruptions occurred. From 2003-2009, the intermediate chamber was gradually filling and only summit eruptions were recorded.

The ultimate driving force for volcanism at the Klyuchevskaya Group is probably the generation of energy (and thus heat) in the Pacific Benioff zone by earthquakes and inelastic strain associated with descent of the subducting Pacific Plate. It was noted by Fedotov that the major eruptions of the Klyuchevskaya Group in 1938, 1945, 1956 and 1975 were preceeded by powerful earthquakes in the Benioff Zone, although numerous other strong earthquakes do not appear to be associated with eruptions. Magma generated at the top of the subducting plate bouyantly ascends into the earths crust, due to the relatively low density of molten rock, where it is stored in the aforementioned magma chambers, before a small proportion ultimately ascends to the surface.

Nighttime view of eruption between clouds	Nighttime view of eruption between clouds

Nighttime view of eruption	Dense steam column rises as lava melts glacier

Powerful persistent strombolian activity at night	Strombolian activity at summit seen from Kliuchi

Ash cloud seen from Kliuchi settlement	Ash cloud seen from Kliuchi settlement

Although climbers have been killed by eruptions of Kliuchevskoi, the volcano is not generally a danger to populated areas, in particular the nearest settlement of Kliuchi on the banks of Kamchatka River. However, lahars resulting from eruptions may damage infrastructure. For example, the road east of Kliuchi was damaged over a stretch of 6 km by Lahars generated by the powerful 1994 eruption. The Kamchatka Volcanological Station of the Russian Academy of Sciences maintains a monitoring station in Kliuchi since 1935 and numerous seismometers in the field monitoring the Klyuchevskaya Group and Shiveluch volcano further north. Relatively accurate predictions of activity at Kliuchevskoi are possible, including the localization of sites of flank eruptions before the onset of surface activity. For example, in 1983, it was already possible to predict the site of an effusive flank eruption to within 2km of the actual vent (Tokarev, 1985. J. Volc. Geotherm. Res. 25, p.173-180.). Seismic data is today augmented by visual data and by data acquired by the ASTER sensor on NASA's EOS satellite, which is able to detect thermal anomalies at the regions volcanoes (see e.g. Rose and Ramsey, 2009. J. Volc. Geotherm. Res. 184, p.367-380). Further, geodetic measurements have been systematically taken since 1978, allowing monitoring of ground deformation as magma levels fluctuate in and below the edifice.

Ash cloud seen from Kliuchi settlement	Ash cloud seen from just west of Kliuchi

Visitor Information

Kliuchevskoi volcano belongs to the Klyuchevskaya Group of volcanoes in Kamchatka, which also includes Bezymianny and Tolbachik, notable for explosive and effusive eruptions, respectively. Petropavlovsk city is the entry point for visitors to Kamchatka and is serviced by regular flights from Moscow. The northern group lies about 6 hours drive away from Petropavlovsk. The mainly unpaved roads initially lead west and then northwards through the central Kamchatka Depression. In order to approach the volcano more closely one needs a driver with local knowledge who knows the forest roads leading to the area above the treeline. Further, a 4WD vehicle is essential as the terrain is boggy in summer and frozen and snow-covered in winter. From below the tree-line there are only few spots with a clear view unobstructed by forest. These include the bridge over Kamchatka River to the west of the volcano and fields near Kliuchi town to the north.

Temperatures can be extremely low (well below freezing already in October) and the weather in the region is extremely unstable so it is important to prepare for any expeditions to the region accordingly. There is no accommodation close to the volcano, but food stores and basic restaurants can be found in Kliuchi and Kosarevsk.

Koryaksky Volcano rising above city of Petropavlovsk	Main road northwards	Bridge over Kamchatka River

Mountain hut	Inside mountain hut

Trying to prevent water supplies freezing	Gale force winds blow snow into hut

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