VarninG! visit the active stratovolcano without special equipment is not recommended!
Bezymianny (Russian: БезымÑнный — lit. unnamed) is an active stratovolcano in Kamchatka, Russia. Prior to its noted 1955-56 eruption, Bezymianny volcano had been considered extinct. The modern Bezymianny volcano, much smaller in size than its massive neighbors Kamen and Kliuchevskoi, was formed about 4700 years ago over a late-Pleistocene lava-dome complex and an ancestral volcano that was built between about 11,000-7000 years ago. Three periods of intensified activity have occurred during the past 3000 years. The latest period, which was preceded by a 1000-year quiescence, began with the dramatic 1955-56 eruption. This eruption, similar to that of Mount St. Helens in 1980, produced a large horseshoe-shaped crater that was formed by collapse of the summit and an associated lateral blast. Subsequent episodic but ongoing lava-dome growth, accompanied by intermittent explosive activity and pyroclastic flows, has largely filled the 1956 crater.
Foto from February 18, 2005.
Bezymiannaya Sopka is located in the central part of the Klyuchevskaya volcano, south-west of Klyuchevskaya. Stratovolcano are complex volcanic areas, slightly elongated in sublatitudinal direction. The top is crowned with a crater the size of 1,3 × 2,8 km and a depth of 700-1000 m currently in the crater formed by extrusion of andesitic dome of the New. The top of the dome has moved beyond the edge of the crater. The slopes of the volcano are covered with lava flows and pyroclastics. The eastern slope is complicated pothole formed by the eruption of 1956. In the southern and south-western foot of the array are 16 extrusive domes of different sizes and ages. Nameless volcanic massive volcano began to form 10-11 thousand years ago on the Late extrusive domes previous eruptions. The latter, in turn, is located on the volcanic formations of volcanic stone. Modern stratovolcano Nameless emerged 5-5.5 thousand years ago.
Topography map of Bezymianny active stratovolcano in Kamchatka, Russia.
Over the last 2.5 thousand years are three period of heightened volcano: 2400-1700, 1350-1000 years and 1955-1956. Each period is characterized by a powerful explosive activity and lava effusion andesite and andesite-basalt composition. Catastrophic eruption 1955-1956 period occurred after 900-1000-year-old peace and continues to this day. In October 1955, the gradual rise of the earthquake volcanic character, then began a fairly strong ash eruptions. In December 1955 and January-February 1956, it (the eruption) has reduced its activity, but it has become celebrated squeezing rigid extrusion and destruction of apical part of the building. March 30, 1956 at the volcano experienced a catastrophic explosion, which completely destroyed the vertex and part of the east building. Formed on top of a rather large and deep crater, and on the eastern side – a deep pothole. The height of the volcano has decreased by 200 m detrital material of construction was thrown out in an easterly direction to a distance of 25-30 km, where it was deposited in the form of an oval area of ​​500 km ² and a capacity of 0.5 to 15-20 m The volume of material ejected by the explosion directed was 1 km ³, the rate of release was 300-500 m / sec. Following directional explosion erupted plinian type. Eruptive cloud loaded with ash, rose to 35-40 km and 5 km band began to spread in the north-east. Along with the ash cloud from the crater began active pyroclastic flow of products in the form of streams, which filled the valleys near the volcano, and the bed of the river dry Hapitsa down to a distance 128 km from the center of eruption. The thickness of these deposits amounted to 25-340 m, and volume – 0.8 km ³. The deposits on the composition of sand and silt are hornblende andesite. In addition, following the culmination of an explosion in the crater of the volcano started to grow new extrusive dome, which in July 1956 had a height of 320 m and 600-650 m diameter at the base of the dome formation was accompanied by explosions of varying strength and rolling pyroclastic flows along the eastern trough. Separate streams have length of 8 to 15 km and the power from 5 to 20 pm In addition to the explosions at the dome was observed squeezing hard blocks and plastic lava, and in 1977, at the final stage of the eruption, the slopes of the extruded lava began to pour.
The most violent eruption was noted on the dome in 1985. It is accompanied by a blast that destroyed the houses of volcanologists, located on the northern ridge, 3.5 km from the center of eruption. During the eruption occurred fairly large collapse of the eastern slope of the dome, which may have contributed to the appearance of directed blast.
The chemical composition of the products of construction varies from 54.5 to 62,5% SiO2, ie from andesitic basalt to andesite-dacite products last eruption – from 60,5 to 56,2% SiO2. Is a decrease in the basicity of andesite, which is characteristic of all cycles of eruptions mentioned above. The mineralogy is horny obmankovye-andesite-dacites, andesites and two-pyroxene andesites, basaltic andesites. In quiet periods of volcanic activity in the apical part of the dome is marked active gassing. Their composition – SO2, H2S, CO, CO2, H2, CH4, and so their concentration is high enough. Due to frequent landslides and rock avalanches high concentration of gases visit top of the dome without special equipment is not recommended.
Here’s what he wrote in 1955 in his classic book “Volcanoes” academic Zavaritskii: “Nameless Sopka, altitude 3150 m (now on the cards – 2882 m. – Ed. Site), is an extinct volcano, located near with stones and south of Klyuchevskaya volcano. This rather new volcano. convex vertex Nameless busy firn field, where the glacier down to the river dry Hapitse. ”
The absence of any signs of activity in historical times has caused to him for a while neglect. And, perhaps, only a connoisseur of Kamchatka volcanoes older generation, as Piip, believed that the hill can still surprise. The assumption was justified, and, moreover, very soon.
In 1955, the station began Klyuchevskoy seismographs recorded numerous aftershocks in the direction of the Nameless. But distrust of him was so strong that it pushes considered harbingers of the emergence of a side of the crater Klyuchevskoi. Suddenly, Oct. 22, in the year the book was published Zavaritskii, dead has risen!
The eruption began massive emissions of ash, rising to a height of 5 km, but then the volcano started to die down, and it seemed that this awakening and it will end. But on March 30 next, in 1956, a grand explosion shook the neighborhood, and a huge billowing cloud of swirling sent ash to a height of 35 km. The top of the volcano was destroyed in its place the crater diameter of 1.5 km, and the height of the volcano has decreased by 250 m
The blast was directed at an angle to the horizon to the east, to the Big Hapitse. Explosions at a distance of 25 km were flattened or burned trees, covered with shrubs. Glowing ashes, sand, debris covered the area with a thick layer of about 500 square meters. km, destroying all vegetation. Mass accumulated over the winter snow had melted quickly, and mudslides swept into the valley Large Hapitsy, carrying back the trees and debris of all sizes. Powerful stream swept through its valley, forming before it flows into the Kamchatka impassable obstruction from trees, rocks and mud. Muddy and poisoned by sulfur impurities of water flow for many days to make the water unfit for drinking Kamchatka and caused mass death of fish.
After the formation of the crater with its bottom began squeezed viscous lava dome – a new cone. In 1966, 10 years after the eruption, when climbing on it was felt that he was full of life. From time to time under the feet of strong aftershocks were felt, the slope rolled boulders of the many crevices rose smelling sulfur dioxide gas jets translucent. Climbing was stopped.
The eruption in 1956 is considered one of the largest in the total Earth in historical times. After it happened on an unnamed two weak eruptions in 1961, 1966 and more powerful – in 1977. Revitalization was observed in 1984, but in 1985 the volcano gave a new surprise.
In late June, began to register tremors. Immediately was sent under the leadership team of volcanologists PP Firstova. And June 29, the volcano exploded. Again there was a directed blast east, but enormous power, the strength – the second after the explosion in 1956. No one expected. The nature of the volcano was considered to be studied, used to shock, and the band nearly died.
Scorching cloud swept by 12 miles, killing a young, newly launched attack on the desert vegetation. Were destroyed and houses built by volcanologists at the volcano, fortunately uninhabited. Growing up in 1956 after the eruption of a new dome survived, but the size of the crater increased.
Explosion of the volcano Bezymianny , October 22, 1955
Unique rarity photo Kamchatka pilot observer A. Semenov
On the Kamchatka Peninsula, in the heart of Klyuchevskaya volcano group of giant, has settled a relatively small height hill (3085 meters), which because of its inexpressive and has not received a name and a directory of volcanoes appeared as Bezymianny. This hill was considered an extinct volcano. On her awakening heralded tremors registered on volcanological station keys, located 45 kilometers from the Nameless. The eruption began at the dawn of October 22, 1955. Of the keys have been seen clouds of white smoke appeared over the eastern slope Klyuchevskoi. Then began falling ash. A few days rising above the crater dark plume of volcanic emissions reached an altitude of 8 kilometers. In a monstrous cloud of night were seen tremendous lightning. Explosions, one stronger than the other, did not stop for the whole of November. On some days, the shroud of ash hanging over the volcano was so thick that out the sun rays in the Keys lit the lamp in the houses and the cars came with lights on. A month crater has grown from 250 to 800 meters.
In late November, decreased activity of the volcano, eruptions occurred less and less, but it began to grow in the crater of viscous lava dome, closed out the volcanic gases. The pressure inside the volcano has reached such strength that the long-hardened old dome, adjoining to the volcano, gradually climbed almost 100 meters and shifted to the south-east.
Last March 30, 1956 there was a huge explosion. Shot up over the volcano oblique pillar of fire, to tend to the east at an angle of 30 degrees. Above it, too obliquely, clouds of black smoke that after one or two minutes, shut mountains. A cloud of ash, like a giant fan, rushed upward and outward, reaching an altitude of about 40 kilometers. In Ust-Kamchatsky, that is 120 kilometers from the volcano, the cloud obscured the horizon. She seemed impenetrably black, only the edges of the light in the rays of the setting sun was bright golden. A quarter of an hour after the explosion, saw a jet of gas shot up over a black veil. It reached an altitude of 45 kilometers. Soon sent ash cloud covered the volcanological station keys. Started ash falls. First fell some large grains up to 3 mm. It seemed like a hailstorm has a windowpane. Ash falls gradually increased, and soon came a thick darkness, it was impossible to see the object, a present to the eyes. The area covered with ashes, was 400 kilometers in length and in width – 100-150 kilometers. Its total volume was at least 0.5 billion cubic meters.
But the full picture of the disaster was not obtained until after managed to visit around the volcano. Nameless has changed beyond recognition. From the right, slightly truncated cone, he became a semi-circle caldera. Ancient dome, raised at the first stage of the eruption, now absent. In place of the summit and the south-eastern slopes of Mount yawned a huge crater in the form of half-ring of 1500 x 2000 meters. The top of the volcano was destroyed by explosion. His height was reduced by 200 meters.
At a distance of over 10 kilometers it was buried under a half-meter layer of volcanic sand. Jet of sand stripped bark from trees within a radius of 30 kilometers. All thin trees were broken. Home – base volcanologists (fortunately without people), located 12 kilometers from the eruption, in the literal sense of the word was blown away from the face of the earth: from him there was not a board.
Under a huge layer of the fallen from the sky hot sand began the rapid melting of snow. Arisen powerful mudslides, pulling fragments of rocks weighing hundreds of tons, rushed through the valleys, destroying everything in its path.
After March 30 paroxysm occurred last phase of the eruption. The new huge crater began to rise two domes. When in August volcanological station chief Keys G. Gorshkov climbed the Nameless, the first of these domes and reached a height of 320 meters. In November, the eruption ended.
Bezymianny eruption occurred in a completely deserted area. The largest volcanic disaster of the century is not claimed any lives.