Shiveluch volcano, also sometimes referred to as Sheveluch, is the northernmost active volcano on Kamchatka Peninsula, Russia. It is also the largest active andesitic eruption center in Kamchatka, with a volume of about 1000 cubic kilometers. The Aleutian Island Arc and the Kurile-Kamchatka Arc subduction zones meet near Shiveluch and probably explain its high magma output. Shiveluch complex comprises the remains of "Old Shiveluch" (3283 m), a voluminous, predominantly effusive, conical edifice which suffered catastrophic collapse at least 10,000 years ago and "Young Shiveluch" (2800 m), a lava dome complex which has grown in the resulting 7 km wide collapse scar. Young Shiveluch is notable for a relatively high frequency of edifice failures leading to massive debris avalanches inundating the landscape to the south and southwest of the Young Shiveluch lava domes. More than 13 large scale sector collapse events appear to have occurred in the last 6000 years, with the largest event in approx.1430 having a volume of over 3 cubic km and inundating an area of over 200 square kilometers. The most recent was in 1964, when 2 cubic km of dome material was mobilized and inundated an area of 98 sq. km. The landslide triggered a Plinian eruption in a sequence of events probably similar to those at most previous sector collapses of Shiveluch. The 1964 event is described in more detail below. A new cycle of dome growth resumed in the 1964 collapse scar after a repose period of 16 years, with periods of dome growth being observed in 1980-1981, 1993-1995 and 2001-2013 (ongoing).
Ash venting episode from summit of dome
Incandescent rockfall down flank of lava dome
The structure of Old Shiveluch and the transition to Young Shiveluch are explained in detail by Gorbach et al. (J. Volc. Geotherm. Res. 263(1), p.193-208 (2013)). The entire massiv started to form about 60-70 ka BP and has a volume of about 1000 cubic km, of which the base consists largely of products of explosive volcanism, accounting for about 60% of Old Shiveluch, whilst the upper Old Shiveluch cone was largely composed series of overlying thick basaltic-andesitic lava flows which were ultimately erupted from at least 4 vents, the remains of which are found around the collapse crater edge, with remnants of the main crater being found near the summit. The location of the craters (Southern, Baidarny, Western and Central Vents) and also of numerous intrusive dikes around the crater edge suggest that this was a zone of weakness where magma could easily penetrate and which predisposed it as the site of edifice failure. In the summit region, lava flows were initially emplaced near-horizontally at elevations of just under 2000 m, and were 40-50 m thick, but as growth of Old Shiveluch progressed, flows were emplaced at angles up to 40 degrees and were from 80 m thick near the main summit to 20 m thick near their ends. At the time of collapse the volcano may have reached a height of about 4000 m and had a central crater about 500 m deep and nearly 1 km wide.
It is noted that several dates have been proposed for the large-scale sector collapse which destroyed Old Shiveluch and formed the huge horseshoe-shaped crater in which Young Shiveluch subsequently formed. Dates of 10ka BP are suggested by Belousov, based on age of Old Shiveluch upper lava flows, 23-24 ka BP by Meleksetev, based on interaction with glaciation, and an at least three-stage collapse starting about 15.8-16 ka BP is proposed by Pevzner based on radiodating of organic matter in debris avalanche deposits (see Gorbach et al. 2013 for references). The authors also disagree on the volume of the collapse with figures of 30-100 cubic km being proposed. Irrespective of the exact figure, it is clear that the collapse represents the largest such event known in Kamchatka.
For a detailed discussion of the petrology of Shiveluch, the reader is referred to Gorbach et al. 2013. About 75% of the volume of Old Shiveluch is constituted by magnesian andesites with from 53.7-63.8% silicate. These andesites were erupted during the initial explosive phase which produced the old pyroclastics forming the base of the complex but also during the initial effusive phase. No abrupt change in lava composition was associated in this change of style of activity. Over time, an increase in MgO could however be observed, whilst levels of silicate, aluminium oxide, potassium oxide and sodium oxide gradually decreased. The magnesian andesites were erupted by the Central and Western vents which appear to have had overlapping periods of activity. The peripheral Nordic and Semkorok dome complexes were also formed by this lava type. The second main type of lava found at Old Shiveluch is high aluminium basaltic andesite with 53.5-55.7% silicate. This was erupted sequentially by the Western, Baidarny and Southern vents as activity at the complex migrated in a SW direction over time. The summit crater was not magmatically active by the time of the collapse and was extensively hydrothermally altered.
Following the collapse of Old Shiveluch, a major change in magma composition occurred. This may be related to a reorganization of the magma feeder system partly in reponse to the huge change in lithostatic pressure due to the removal of the edifice. Whilst the volcano returned to the eruption of magnesian andesites (as initially erupted at Old Shiveluch) and accordingly changed to a more explosive style of volcanis associated with cycles of dome construction and failure, the exact composition of the Old Shiveluch and Young Shiveluch magnesian andesites is different. It appears that Young Shiveluch has a smaller shallow magma chamber where direct mixing of evolved andesite and ascending primitive basaltic magmas can occur, whilst under Old Shiveluch, fractional crystallization of basaltic magmas at medium and shallow depths dictated the exact properties of erupting magmas.
The present summit of Young Shiveluch is represented by the 2800 meter high peak of "Fourth Summit Dome". During the evolution of Young Shiveluch, a further dome complex known as the Karan Domes was formed outside of the perimeter of the Old Shiveluch Collapse scar immediately NW of the location of the Baidarny Vent.
The top of the peripheral (upper) magma chamber of Shiveluch could be as little as 4 km under the edifice, whilst a larger crustal chamber starting at a depth of 20 km may also be involved in intermediate storage of magma. The chambers have been calculated to have volumes of about 100 and 200 cubic km, respectively (Fedotov et al. 2000. Volcanol. Seismol. 22(3), p. 239-258). These volumes may however be vastly exaggerated. Based on studies of the 2001-2004 extrusion period, Dirksen et al. (J. Volc. Geotherm Res. 155, p.201-226 (2006) calculate that the upper chamber has a volume of 7 cubic km, resides at a depth of 5-6 km or more and is connected to the dome by a cylindrical conduit with a diameter of between 53 and 71 meters.
Earthquakes at a depth of around 70-130km appear to correlate to activity at the volcano (Gorelchik et al. 1997. J. Volc. Geotherm. Res. 78, p.121-132), suggesting that magma is ultimately sourced from at least this depth.
The active volcanoes in Kamchatka belong to a SW-NE oriented volcanic arc which extends southwestwards through the Kurile Islands. Arc formation is linked to northwestward subduction of the Pacific Plate under the Okhotsk and Kamchatka-Okhotsk Blocks (together forming the Okhotsk Microplate) at a rate of 7.5-8.2 cm per year. The Aleutian Islands represent a second volcanic arc, resulting from northward subduction of the Pacific Plate under the North American Plate. The two subduction zones intersect off the coast of Kamchatka, with the NE oriented Kamchatka plate boundary meeting the NW-oriented western Aleutian plate boundary at an angle of roughly 90 degrees. At the western Aleutian plate boundary, the pacific plate is essentially moving NW-wards, more or less parallel to the plate boundary so that little or no subduction can be taking place in this area.
By analysis of the passage of seismic P- and S-waves during natural earthquakes, in a technique known as regional tomography, the location of hypocenters attributed to the process of subduction of slabs can be detected, and thus indirectly the rough 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 up to 900 km being detected in places. The plate is already about 100 km below the surface as it passes under the E coast of Kamchatka and at a depth of about 200 km when about 150 km inland.
The situation becomes more complex in northern Kamchatka where the intersection with the western Aleutian Arc complicates the subduction mechanism. Here, Koulakov detects a subducting slab down to a depth of 250-300 km which may be a remnant of a now passive subduction complex. Parts of the stagnant slab may be gradually breaking off. Certainly, there is a discontinuity in the slabs relating to subduction under Kamchatka and the Aleutian Islands.
It is likely that this discontinuity is intricately linked to the highly productive volcanic centers of Shiveluch and Klyuchevskaya Group. Levin et al. 2002 (Nature 418, p.763-767) attribute changes in volcanism in northern Kamchatka to breaking off of subducting slab sections about 5-10 and 2 million years ago. The latter event is considered linked to the high productivity of e.g. the Klyuchevskaya Group of volcanoes and the presence of adakite ("slab-melt") in the products of Shiveluch volcano, which is also notable for unusually high productivity for a subduction zone volcano.
Ferlito (Earth Sci. Rev. 105(1-2), p.49-69 (2011) suggests that Shiveluch lies above two distinct slabs subducting at different angles which account for the distinct compositions of the Old Shiveluch basaltic endesite effusions and the current magnesian andesites. The actual exact mechanisms occuring at the plate intersection remain controversial.
(Relatively) clear view of dome. Summit of Old Shiveluch is behind dome
Dome steaming at dawn with typical morning cloud forming in front
Lava dome at dawn.
Note: Step in landscape (right middle) is Toreva block from 1964 collapse
Lava dome under moonlight
Old dike intrusions in front of dome, Fourth Summit Dome at top left
Note: Extruded viscous lava flow from 2011 lies on right side of dome
Dome with partially filled erosion gulley (Kamenskaya Drainage (?)) in foreground
View of dome from SW with warm deposits in foreground
Nighttime incandescent rockfall from growing dome
Nighttime incandescent rockfall from growing dome
The current cycle of dome growth, covering the years 1980-1981, 1993-1995 and 2001-2013 (ongoing), has already emplaced a several hundred meter high lava dome. Dome growth fluctuates significantly and since 2001 was most intense following explosive eruptions in 2001, 2004, 2005 and 2010 (Zharinov and Demyanchuk, 2013. J. Volc. Seismol. 7(2), p.131-144).
The dome has been gradually increasing in height, yet has suffered several setbacks in the form of partial collapse events. The 27. Febr. 2005 eruption removed the summit and part of the western section of the lava dome, reducing its height by about 125 meters. About 0.04 cubic km of dome was removed and in total a volume of 0.2 cubic km of material was erupted. Pyroclastic flows extended as far as 25km from the dome in a SW direction along the Baidarnaya River and inundated about 21 sq. km of land (Girina et al. 2007. J. Volc. Seismol. 1(4), p.237-247). [Note: On Sept. 22 in the same year, pyroclastic flows again extended in the same direction, with runouts of 20 km. These were triggered by failure of an extrusive block and show that even small events can have a potentially devastating effect]. On 27. October 2010, a further particularly violent eruption took place. At this time, the dome had reached a height of 563m over its base (2740m a.s.l.) and was about 700 meters wide at its summit. The eruption resulted in destruction of about half of the dome, in particular its SE section, leaving a 2.5 x 1.1 km collapse scar. 0.27 cubic km of material were deposited over an area of 25 sq. km and ash was deposited over an area of 2000 sq. km. Pyroclastic flows extended 15 km ESE and destroyed forest around the Bekesh River valley and ash clouds reached heights of up to 12 km.
Readers interested in lava domes in general may also find the extremely detailed page on Soufriere Hills volcano interesting, or the pages relating to lava dome emplacement at Chaiten or Paluweh volcanoes.
ANIMATION OF NIGHTTIME INCANDESCENT ROCKFALLS FROM LAVA DOME:
Ash eruption at night. Fourth Summit Dome on left.
Daytime ash eruption, Baidarnaya valley extends to bottom left of image.
VIDEO OF ERUPTION OF ASH CLOUD FROM SUMMIT OF LAVA DOME:
Deep erosion gulley (Kamenskaya Valley) in deposit field
Deep erosion gulleys in deposit field
Deposits in Baidarnaya valley remain warm
Pumice deposits in snow
Huge broken boulder on flow field
Baidarnaya valley largely filled with pyroclastic flow deposits
Baidarnaya valley extending down flank
The devastating 1964 Eruption can be considered as typical for the large scale catastrophic sector collapse events punctuating the recent history of Shiveluch volcano. Belousov (J. Volc. Geotherm. Res. 66, p.357-365 (1995)) provides a detailed acount of the eruption. Seismic unrest preceding the eruption was first noted on 24. Jan. 1964. An earthquake swarm was detected in May and a strong tremor on 25. July marked the beginning of a gradual increase in seismicity leading up to the eruption. During October, a strong increase in tremor frequency and intensity occurred until finally constant tremor was observed in the early hours of the morning of 12. November. At 7:07 in the morning, edifice failure occurred, with the mobilization of 1.154 cubic km of dome material. This was shortly followed by a series of phreatic explosions of gradually increasing intensity which ejected 0.01 cubic km of ash. At 7:20, volcanic tremor suddenly intensified as juvenile material started to be erupted. This resulted in a powerful Plinian eruption which launched 0.3 cubic km of juvenile andesitic material into the atmosphere, creating a 15 km high eruption column, accompanied (from about 7:47 onwards) by pumiceous pyroclastic flows with a total volume of up to 0.5 cubic km and inundating an area of 50 sq. km. The event was powerful but short-lived as activity rapidly declined at 8:22. The eruption left a southward-opening horseshoe-shaped crater with a diameter of about 1750 meters. Location and dimension were almost identical to the crater left by the 1854 eruption.
The fine ash layer overlaying the landslide deposit to a depth of up to 8cm contained explosively fragmented partially altered andesites and included some gypsum. This is presumed to have been created as the phreatic explosions destroyed the hydrothermal system at the base of the mobilized dome. No juvenile material was found in the landslide deposit or the overlying ash layer, suggesting that magma had not yet entered into the dome at the time collapse was instigated. However, due to removal of the dome, depressurization of the system allowed rapidly rising magma to reach the surface in under half an hour of the sector collapse event.
Due to the preceeding tremor activity, it is however almost certain that rising magma triggered the collapse event. Interestingly, landslide deposits from previous sector collapse events at Shiveluch also don't appear to contain juvenile material (Belousov et al. 1999. Bull. Volcanol. 61, p.324-342). One could conclude that the risk of large-scale sector collapse is low whilst extrusion is taking place, possibly since whilst there is an existing extrusion channel the strain on the edifice is sub-critical but when a new batch of magma approaches a partially cooled and thus more viscous dome the strain on the structure may surpass a critical level (my comments). The increasing vapour pressure in the dome and localized earthquakes at its base as magma approaches are considered the primary triggers by Belousov.
Based on analysis of the deposits, the 1964 collapse, and possibly most of the previous collapses, involved a retrogressive multi-stage collapse wherein with the leading blocks strongly disintegrating and spreading as a debris avalanche, whilst the last-released blocks are far less fragmented and may simply slip whilst rotating slightly backward to a short distance from the dome (Belousov et al. 1999. Bull. Volcanol. 61, p.324-342). These huge blocks can leave a series of steps in the landscape (facies blocks / toreva blocks), several of which were formed in 1964. The highest step, over 100m high is still clearly visible 50 years later. The landslide deposit may retain some larger fragments of dome material which may form the typical hummocks found in debris flow deposits.
Further large-scale collapse events of Young Shiveluch occurred 600, 1000, 1600, 2600, 3700 and 5700 years ago according to Belousov. Ponomareva et al. 2006 (J. Volc. Geotherm Res. 158, p.117-138) attribute deposits to events 500, 1100, 1450, 1600, 1700, 1850, 1900, 2550, 3100, 3700, 4000, 5500 and 5700 years ago. Both authors used carbon dating of soil or tree remains in deposits to determine approximate eruption dates. Neither author mentions the 1854 eruption which was reported to have involved debris flows with runouts of about 20 km associated with failure of the dome complex, including part of the "Fourth Summit Dome" which is the summit of Young Shiveluch. Ponomareva mentions the event and considers its magnitude exaggerated in historical records, with no landslide deposits thereof localized beyond 8 km from the crater. This also casts doubts on claims of pyroclastic flow runout distances of up to 90 km.
Dead Trees at Periphery of 1964 Landslide Deposit Caught in 2005 Pyroclastic Surge
Pyroclastic flows generated during the 27. February 2005 eruption killed a significant amount of forest (Grishin, 2009. Russian J. Ecol. 40(2), p.146-148). Whilst trees caught in the center of the flow were flattened, moving to the periphery, where trees were impacted by a pyroclastic surge associated with the flow, trees remained standing. On the sides of the Baidarnaya valley, which largely channelled the flow, trees were found standing with blackened trunks to a height of 1.5-2 meters. The trees suffered little mechanical damage except near the flow edge and in the upper valley, where the flow would have been more dynamic, yet the thermal impact sufficiently scorched the stems and removed the foliage for the trees to be killed. Whilst trees caught in the pyroclastic flow caught fire, the surge does not appear to have been hot enough for this to occur, suggesting temperatures of under 250'C. The effect of pyroclastic flows on forest is also shown in the section on Chaiten volcano.
Shiveluch volcano is the most northerly historically active volcano in Kamchatka. Petropavlovsk city, with its International Airport is the entry point for visitors to the region. Shiveluch lies about 10 hours drive from Petropavlovsk, along largely unpaved roads. The Klyuchevskaya Group including active Kliuchevskoi, Bezymianny and Tolbachik volcanoes is passed en route to Shiveluch. The volcano can be seen from Kliuchi village, which is the nearest settlement to the volcano, and also the point where one must cross Kamchatka River before approaching it. A ferry was in use in 2013, but a new bridge should be completed shortly. Local guides may be able to take visitors onto the zone devastated by the 1964 eruption, where it is possible to drive several kilometers towards the active lava dome with a 4WD vehicle. However, visitors to this area must be aware that collapses of the lava dome can occur without warning and produce dangerous debris avalanches and pyroclastic flows which would kill anyone in their path. It is therefore not recommended to enter this zone. Further, temperatures can be extremely low (well below freezing already in October) and the weather in the region is unstable. There is no tourist infrastructure near the volcano, but food stores and a basic restaurant can be found in Kliuchi.
Avachinsky volcano (Site of huge collapse 30000 years ago) towering above Petropavlovsk.