Eruption of the Nameless Volcano 1956. Nameless Volcano. The role of Bezymyanny in world volcanology

55°58′ N. w. 160°36′ E. d. HGIOL

Nameless- an active volcano in Kamchatka, near Klyuchevskaya Sopka, about 40 km from the village of Klyuchi, Ust-Kamchatka region.

Current state[ | ]

Absolute height - 2882 m (up to the city - 3075 m), the composition includes the remains of an old volcano destroyed by the 1956 eruption (in the south-eastern part of the massif), a young active stratovolcano and a crater on the site of the old volcano with a diameter of 1.3x2.8 km . There are numerous lava flows on the slopes, and 16 extrusive domes at the foot.

Eruptions [ | ]

Bezymyanny Volcano before the catastrophic eruption of 1955-56

The famous catastrophic volcanic eruption on March 30, 1956 was identified by G. S. Gorshkov and G. E. Bogoyavlenskaya as an independent type - “directed explosion” or “Bezymyanny type”, which is recognized by world volcanology (“directed blast”, “lateral blast”, "type Bezymianny")

Eruption 1955-1956[ | ]

Eruption 1955-1956 was the first in this area since 1697 and occurred, according to tephrochronological studies, after a 1000-year dormant period. Before the eruption, the volcano had the shape of a regular cone with a height of 3085 m (a stratovolcano of predominantly andesitic composition, complicated by summit and side extrusive domes). The eruption began on October 22, 1955, after a 23-day earthquake swarm. Until March 30, 1956, the eruption was of a moderate, Vulcan nature ( pre-climax stage). During this period, a crater with a diameter of 800 m was formed at the top of the volcano, from which frequent ash emissions occurred to a height of 2-7 km. At the end of November, the squeezing out of the viscous lava dome began in the crater. Simultaneously with the growth of the intracrater dome, a strong swelling of the southeastern slope of the volcano began. The amount of deformation, estimated from photographs, reached 100 m. The deformation of the slope was due to the fact that part of the magmatic melt was introduced in the form of a cryptodome (near-surface intrusion) into the volcano building.

Catastrophic eruption on March 30, 1956 ( climax stage) was triggered by the collapse of the eastern slope of a volcanic structure with a volume of 0.5 cubic meters. km. The collapse transformed into a cold (< 100 °С) обломочную лавину , скорость которой превышала 60 м/с. Обломочная лавина образовала три ветви, вложенные в речные долины . Максимальный путь (22 км) прошла центральная ветвь. В процессе распространения обломочная лавина сдирала и толкала перед собой вал материала подножья вулкана (снег, почву, аллювий , растительность), который образовал протяжённые грязевые потоки. Сразу за обрушением последовал катастрофический направленный взрыв, вызванный тем, что обвал резко уменьшил литостатическое давление на магму , внедрившуюся в постройку на докульминационной стадии извержения. Материал, выброшенный взрывом (0,2 куб.км.), распространился вдоль восточного подножия вулкана в виде пирокластической волны (турбулентный поток горячей смеси газа и пирокластики). Скорость потока превышала 60 м/с, температура составляла около 300 °C. После направленного взрыва произошло извержение пирокластических потоков протяжённостью более 20 км. Высота эруптивного облака извержения достигла высоты около 35 км. В результате извержения образовался подковообразный кратер диаметром ~1,3 км, открытый на восток. У восточного подножья вулкана на площади ~500 км² деревья и кустарники были сломаны и повалены в направлении от вулкана. В зоне разрушений возник покров специфических пирокластических отложений (отложения направленного взрыва). После пароксизма (post-climax stage) in the horseshoe-shaped crater, a dome of viscous lava began to squeeze out, the formation of which continues to the present day.

Formation of the “New” dome[ | ]

The formation of the “New” dome began immediately after the culminating stage on March 30, 1956. In the first years, there was a continuous squeezing of hard obelisks on the dome. Subsequently, the growth of the dome became intermittent and, along with hard blocks, viscous lava flows began to be squeezed out since 1977. The viscosity of the lava continues to gradually decrease and the length of the lava flows gradually increases (the decrease in viscosity is due to a gradual decrease in the silicic acid content). Currently, lava flows cover the entire surface of the dome, which almost filled the 1956 crater. The formation of the dome throughout its history is accompanied by weak to moderate explosive eruptions with the deposition of small block-ash pyroclastic flows and associated pyroclastic waves of the ash cloud. The frequency of eruptions reaches 1-2 per year. Among the explosive eruptions accompanying the growth of the dome, we can roughly distinguish the relatively strong eruptions of 1977, 1979, 1985 and 1993. The longest pyroclastic flows associated with the growth of the “Novy” dome traveled a distance of 12.5 km (1985). Until 1984, pyroclastic flows did not have a noticeable eroding effect. During subsequent eruptions, pyroclastic flows began to cut troughs on the slope of the dome. Simultaneously with the increasing erosive effects of pyroclastic flows during eruptions, large collapses of old parts of the dome began to occur. The largest collapse of the dome occurred during the 1985 eruption of the Bezymyanny volcano in Kamchatka.

Malyshev A. I. Life of a Volcano. - Ekaterinburg: Publishing house of the Ural Branch of the Russian Academy of Sciences, 2000. - 262 p.
Alidibirov M. A., Bogoyavlenskaya G. E., Kirsanov I. T. et al. Eruption of the Bezymyanny volcano in 1985 // Volcanology and seismology. - 1988. - P. 3-17.
Sediments and sequence of events of the Bezymyanny volcano eruption on March 30, 1956 (Kamchatka): sediments of a debris avalanche // Volcanology and seismology. - 1998. - No. 1. - pp. 25-40.
Belousov A. B., Belousova M. G. Deposits and sequence of events of the Bezymianny volcano eruption on March 30, 1956 (Kamchatka): deposits of a directed explosion // Volcanology and seismology. - 2000. - No. 2. - P. 3-17.
Bogoyavlenskaya G. E., Kirsanov I. T. Twenty-five years of volcanic activity of the Bezymyanny volcano // Volcanology and seismology. - 1981. - No. 2. - P. 3-13.
Gorshkov G. S., Bogoyavlenskaya G. E. Sopka Bezymyannaya in 1956-1958. // Bulletin of Volcanology. - M.: Nauka, 1961. - No. 31. - pp. 17-22.
Dubik Yu. M., Menyailov I. A. A new stage of eruptive activity of the Bezymyanny volcano // Volcanoes and eruptions. - M.: Nauka, 1969. - P. 38-77.
Florensky P.V. Unique shots // Nature. - 2007. - No. 1. - pp. 38-39.
Belousov A., Voight B., Belousova M. Directed blasts and blast-currents: a comparison of the Bezymianny 1956, Mount St Helens 1980, and Soufriere Hills, Montserrat 1997 eruptions and deposits // Bulletin of Volcanology. - 2007. - No. 69. - pp. 801-840.
. Scale: 1: 100,000. Condition of the area in 1979. 1986 edition

The famous Bezymyanny volcano is located in the eastern part of the Kamchatka Peninsula. Its peak for a long time had the shape of a regular cone, the height of which at the beginning of the last century was 3085 meters. The volcano was considered extinct because it had been dormant for about 1000 years. But on October 22, 1955, an eruption began, which until March 30, 1956 was moderate. Such an eruption could be described as the awakening of a volcano.

For six months, the volcano smoked, and the hill on which Nameless woke up was what is called “shaking.” It seemed as if the hill was being shaken by convulsions. For six months, gas explosions with ash emissions and lava splashes were heard in the area. During these six months, a new crater with a diameter of 800 m was formed at the top of the volcano, from which frequent ash emissions occurred to a height of 2 to 7 km. But on March 30, the volcano simply exploded. This eruption was catastrophic according to scientific classification.

With a terrible roar, hot gases demolished the top of the old volcano cone along with the newly formed crater, so that it became 200 meters shorter, and a new giant horseshoe-shaped crater with a diameter of 1.3 km, open to the east, appeared on the eastern slope of the hill. From it into the atmosphere to a height of 35 km. a huge black cloud of volcanic ash (tephra), heated to 300 degrees, shot up. Following the explosion and the release of a black cloud of gases and tephra, huge streams of fiery lava poured onto the ground from the hole. Its speed exceeded 60 m/s, the temperature was about 300 °C. Rushing down, the hot lava tore off and pushed in front of it the soil, huge boulders and vegetation from the foot of the volcano, falling and cooling hot ash, melting snow, mixing into one mass, forming mud flows that swept away everything in its path. Under the newly formed crater at the eastern foot of the volcano, over an area of about 500 km 2, trees and bushes were broken and felled in the direction from the volcano.

Mud streams, in which ash, lumps of hardening lava and huge boulders mixed with the trunks of uprooted trees, rushed down. They traveled a distance of 22 km. Fortunately, these flows bypassed the village of Klyuchi, located near the Bezymyanny volcano, and no people were injured during this catastrophic eruption of the “extinct” volcano. But clouds of hot ash covered this village, so that its residents, returning from work, were forced to search for their homes almost by touch. But the British were lucky.

The Nameless Volcano gave them a wonderful "show", as the British were soon able to admire for some time unusually beautiful sunsets caused by atmospheric pollution as a result of emissions of volcanic ash.

One of the greatest Peleian-type eruptions was the eruption of Bezymianny volcano in Kamchatka (USSR) on March 30, 1956. It occurred without recorded casualties. The huge Bezymyanny explosion on the Kamchatka Peninsula (USSR) went largely unnoticed, as there were no fatalities. But in terms of intensity it ranks with the most violent Peleian eruptions and as such deserves mention.

Considered extinct, with no record of eruptions in historical times, Bezymyanny Volcano attracted little attention even after it became the epicenter of a series of earthquakes in September and October 1955. Then they decided that the nearby Klyuchevskaya Sopka volcano was to blame for everything.

But on October 22, 1955, Bezymyanny erupted with medium strength, and ash fell until March 29, 1956.

Then, on March 30, 1956, at 17.10, a monstrous explosion split the top of the snow-covered Bezymyanny, which had previously risen to a height of 3048 meters above sea level. Within a matter of seconds, 183 meters of the peak were “cut off” from the volcano, and volcanic dust rose from the crater to a height of 45 kilometers.

Russian volcanologist G. O. Gorshkov, who was nearby in the village of Klyuchi, described this scene as follows:

“The cloud swirled strongly and quickly changed its shape... It seemed very dense and almost tangibly heavy. Along with the cloud, the roar of thunder arose and intensified, accompanied by incessant flashes of lightning. At about 17.40, when the cloud had already passed its zenith, ash began to fall... and by 18.20 it became so dark that it was impossible to see one’s own hand, even if one raised it to one’s face. People returning from work wandered around the village in search of their homes. The thunder rumbled with deafening force and did not stop. The air was saturated with electricity, telephones were ringing spontaneously, loudspeakers on the radio network were burning out... There was a strong smell of sulfur.”

A hot layer of ash, covering an area of 482 square kilometers, melted the snow and formed rapid mud flows in the valley of the Sukhaya Khapitsa River and valleys located on the slopes of adjacent volcanoes. These streams washed away huge boulders weighing hundreds of tons and carried them through the valley, sweeping away everything in their path. Trees were uprooted or burned. Three weeks after the eruption, Gorshkov discovered thousands of streams of fumarolic gases rising from the surface of a 30-meter layer of ash over an area of 47 square kilometers. This area was called “the blast furnace of 10,000 smokes of Kamchatka.” A similar eruption of Mount Katmai occurred in 1912.

Nature and its development by man

The Kamchatka Peninsula belongs to the northern part of the Pacific seismic belt, where earthquakes are frequent and fiery mountains are found in abundance. The entire northern part of this belt is represented mainly by islands; it is the local island arcs that are, as geologists put it, “fire-breathing.” Thus, Kamchatka is a surprising exception, since the peninsula is home to many volcanoes, including active and dormant ones. Bezymianny Volcano (3085 m) lies in the Eastern Range and is located in the so-called Klyuchevskaya group, which includes many other Kamchatka volcanoes. The main fire mountain of the group is Klyuchevskaya Sopka, however Bezymianny has gained perhaps the greatest fame.

The eruption in 1955-1956 was the greatest volcanic disaster of the past century. Fortunately, the volcano is located far from settlements, so the cataclysm was not accompanied by destruction or loss of life. Due to its remoteness from cities and towns, this volcano did not receive any name for a long time. That is why he was included in works on volcanology under the name Bezymyanny. The volcano, which was considered extinct, woke up after many years of sleep in the early morning of October 22, 1955 and began throwing out clouds of hot ash and clouds of grains of sand. A column of dust particles shot up into the air to a height of 8,000 m. A thick ash fall began, forcing residents of the neighboring village of Klyuchi to turn on their lights during the day. Over the next month, the Nameless One only threw out ashes, but the activity of the subsoil, not externally manifested, increased.

Hot sand and ash, falling in tons from the sky, caused intense snow melting near the Nameless Hill. As a result, powerful mud flows arose that rushed down to the river valleys.

The volcano's crater slowly but steadily grew and eventually increased 3.2 times in size, reaching a diameter of 800 m. Over time, activity gradually declined, and in early December the volcano's mouth was completely clogged with solidified lava. Therefore, the pressure of accumulating gases began to increase inside the channel. Under their influence, the dome of lava strata rose 100 m and shifted in a southeast direction. A gas explosion occurred on March 30, 1956.

Origin and age

All Kamchatka volcanoes are geologically very young, most of them are no more than 60 thousand years old. The history of volcanism on the peninsula goes back a long way. Over 70 million years ago, Kamchatka was a chain of volcanic islands like the Kuril ridge, and only after more than 60 million years did the islands unite into a continuous massif that joined the continent.

Destruction of the Bezymyanny cone as a result of the 1956 eruption. The outline shows the original size of the volcanic hill, the three-dimensional drawing depicts the current outlines of the stratovolcano.

About 3 million years ago, mountain building processes began on the peninsula, and at the same time the first volcanic cones of the new era began to form along the growing mountain ranges. 1 million years later, the Kamchatka Peninsula was dotted with ancient shield volcanoes. Subsequently, 50-60 thousand years ago, hills of modern stratovolcanoes (layered), including Bezymyanny volcano, grew on the surface of these volcanoes.

Around the cones of the Klyuchevskaya group there are ridges with an average height of 2000-2500 m. The slopes of the ridges are covered with coniferous forest. But during lava eruptions, forest areas on volcanic hills are completely felled or burned out.

Bezymyanny is an active volcano in Kamchatka, near Klyuchevskaya Sopka, about 80 km from the village of Klyuchi, Ust-Kamchatka region.
The height is 2882 m (until 1956 - 3075 m), it consists of the remains of an old volcano destroyed by the 1956 eruption (in the southeastern part of the massif), a young active stratovolcano and a crater on the site of the old volcano with a diameter of 1.3x2.8 km. There are numerous lava flows on the slopes, and 16 extrusive domes at the foot.
The famous catastrophic volcanic eruption on March 30, 1956 was highlighted by G.S. Gorshkov and G.E. Bogoyavlenskaya into an independent type - “directed explosion” or “Bezymianny type”, which is recognized by world volcanology (“directed blast”, “lateral blast”, “type Bezymianny”).

Eruption 1955-1956 was the first in the historical period (in this area since 1697) and occurred, according to tephrochronological studies, after a 1000-year period of rest. Before the eruption, the structure of the volcano had the shape of a regular cone with a height of 3085 m (a stratovolcano of predominantly andesitic composition, complicated by summit and side extrusive domes). The eruption began on October 22, 1955, after a 23-day swarm of earthquakes. Until March 30, 1956, the eruption was of a moderate, Vulcanic nature (pre-climax stage). During this period, a crater with a diameter of 800 m was formed at the top of the volcano, from which frequent ash emissions occurred to a height of 2-7 km. At the end of November, a dome of viscous lava began to squeeze out of the crater. Simultaneously with the growth of the intracrater dome, a strong swelling of the southeastern slope of the volcano began. The magnitude of the deformation, estimated from photographs, reached 100 m. The deformation of the slope was due to the fact that part of the magmatic melt was introduced in the form of a cryptoculol (near-surface intrusion) into the volcano edifice.

The catastrophic eruption on March 30, 1956 (culmination stage) was triggered by the collapse of the eastern slope of a volcanic structure with a volume of 0.5 cubic meters. km. The collapse transformed into a cold (< 100°С) обломочную лавину, скорость которой превышала 60 м/с. Обломочная лавина образовала три ветви, вложенные в речные долины. Максимальный путь (22 км) прошла центральная ветвь. В процессе распространения обломочная лавина сдирала и толкала перед собой вал материала подножья вулкана (снег, почву, аллювий, растительность), который образовал протяженные грязевые потоки. Сразу за обрушением последовал кастрофический направленный взрыв, вызванный тем, что обвал резко уменьшил литостатическое давление на магму, внедрившуюся в постройку на докульминационной стадии извержения. Материал, выброшенный взрывом (0,2 куб.км.), распространился вдоль восточного подножия вулкана в виде пирокластической волны (турбулентный поток горячей смеси газа и пирокластики). Скорость потока превышала 60 м/с, температура составляла около 300 градусов С. После направленного взрыва произошло извержение пирокластических потоков протяжённостью более 20 км. Высота эруптивного облака извержения достигла высоты около 35 км. В результате извержения образовался подковообразный кратер диаметром ~1,3 км, открытый на восток. У восточного подножья вулкана на площади ~500 кв. км деревья и кустарники были сломаны и повалены в направлении от вулкана. В зоне разрушений возник покров специфических пирокластическлх отложений (отложения направленного взрыва). После пароксизма (посткульминационная стадия) в подковообразном кратере начал выжиматься купол вязкой лавы, формирование которого продолжается до настоящего времени.