MOSCOW, April 12, Vladislav Strekopytov. The strongest eruption of the Shiveluch volcano was accompanied by the most powerful ash emission in 59 years. Under its thick layer were several villages in the north-east of the peninsula. About what happened — in the material.
Similarity of a nuclear winter
In Kamchatka — the activation of volcanoes. On Friday, April 7, powerful emissions began at Bezymyanny. Volcanologists working on the slopes were hit by a severe ash fall, which was accompanied by the fall of small stones and lapilli — fragments of porous volcanic rocks up to five centimeters in size.
According to video and satellite data, the ash column rose to a height of 10-12 kilometers and began to drift towards the village of Klyuchi located 40 kilometers to the southeast. The ash cloud did not reach the settlement then.
On Monday, April 10, the neighboring Shiveluch volcano woke up, and on Tuesday at 06:20 am local time an eruption occurred. The most powerful ejection reached a height of 15-20 kilometers. The sky was covered with ash clouds, and it became dark as night — a picture reminiscent of a nuclear winter.
Now the volcanic activity continues. The villages of Klyuchi and Kozyrevsk in the Ust-Kamchatsky region, as well as Esso in the Bystrinsky region, are covered with ash, in Klyuchi its layer is about 8.5 centimeters. Rescuers with a batch of protective masks left the place. The situation was assigned the maximum level of danger, people are urged not to go out. Car traffic was stopped, air flights were cancelled.
The ash has already spread for about 500 kilometers. According to scientists, if the emissions continue, ash clouds will reach Petropavlovsk-Kamchatsky. The last time something like this was in 1964.
Special situation
Kamchatka volcanoes do not erupt very often. For example, the same Shiveluch operated from 2008 to 2016, and before that, from 2001 to 2003. Activity has been recorded with short breaks since the end of the 18th century, when observations began.
Both Shiveluch and Bezymyanny, and the most famous volcano of Kamchatka — Klyuchevskaya Sopka belong to the Klyuchevskaya group in the north-east of the peninsula. From a geological point of view, it is located at the intersection of two large tectonic structures at the boundary of lithospheric plates.
«The Klyuchevskaya group of volcanoes is located at the junction of the Kamchatka and Aleutian volcanic arcs,» says Pavel Plechov, doctor of geological and mineralogical sciences, volcanologist. special activity is explained by the influence of this triple junction.There is also a version that the reason is the restructuring of the Kamchatka arc itself in connection with the subsidence of a lithospheric plate under it, the edge of which is located just under Shiveluch.
Hot March 1956
Extrusive, or explosive, type of eruptions is accompanied by volumetric emissions of ash and detrital material. This is typical for volcanoes with viscous lava, which does not flow out freely, but is squeezed out gradually, piling up above the vent in the form of a dome that covers the mouth.
Over time, gases accumulate under the dome, and when another portion of magma enters, an explosion occurs . The volume of ash thrown into the atmosphere — a thin detrital material — depends on the size of the dome.
“The volcanoes of the Klyuchevskaya group are characterized by viscous, water- and gas-rich andesitic magmas. This determines the predisposition to explosions,” explains the scientist. “Strong eruptions occur here every 20-30 years and are always accompanied by ash emissions. The mathematical model shows that It usually takes about three weeks for magma to reach the surface before a major explosion.»
The largest eruption in the northeast of Kamchatka, the consequences of which were really catastrophic, occurred on March 30, 1956. Five months earlier, Nameless began to show signs of activity, swelling appeared on the slopes, domes of viscous lava began to grow, and magmatic melt spread throughout the entire volcanic structure.
At some point, one of the slopes of the volcano collapsed, and a debris avalanche, raking up a shaft of snow, soil and vegetation in front of her, rushed down the river valleys. The collapse was immediately followed by a directional explosion, caused by the collapse dramatically reducing the lithostatic pressure holding the magma.
The height of the ash cloud was about 35 kilometers. The material thrown out by the explosion formed a pyroclastic flow — a mixture of high-temperature volcanic gases, ash and rock fragments. Its speed exceeded 60 meters per second, and the temperature was about 300 degrees Celsius. It spread over 20 kilometers.
As in Pompeii
Under the thickness of a similar pyroclastic flow during the eruption of Vesuvius in 79 AD, the ancient city of Herculaneum ended its existence. Neighboring Pompeii, where the flow was less strong, was covered with many meters of volcanic ash.
Plechov is sure that the fate of ancient Roman cities does not threaten Kamchatka villages.
“Firstly, Shiveluch is much farther from settlements. At a distance of 50-60 kilometers from the volcano, one cannot expect such massive ashfalls as in Pompeii,” the volcanologist notes. “Secondly, Vesuvius has a very specific magma, it is much larger saturated with gases.»
People in Herculaneum and Pompeii died mainly not from ash and falling debris, but from poisoning by volcanic gases. The incandescent pyroclastic flow sealed the premises of the buildings, depriving the inhabitants of access to oxygen. Therefore, the remains of the victims were preserved intact. width=»600″ data-crop-height=»402″ data-source-sid=»rian_photo» class=»lazyload» width=»1920″ height=»1285″ decoding=»async» />
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The concentrations of volcanic gases in the vicinity of Shiveluch do not pose a threat to life and health. Ashes are more dangerous — the smallest silicate particles settle in the respiratory tract and lungs. Therefore, people are advised, if possible, not to leave home yet, and if it is still necessary to go out, wear a medical mask.