Sheveluch, Kamchatka
Sheveluch is a great stratovolcano in north-central Kamchatka. Faults
split this volcano into two parts. The northeast side is highest and has
the shape of the original volcano. This portion is not active, is covered
by ice, and is separated from the southwest part by a large fault scarp
(up to 6560 ft/2000 m).
- The lower southwest portion of Sheveluch
has a small stratovolcano cone where eruption still occur. This cone has
a large caldera that opens to the south. Volcanic domes fill this 1.8
mile (3 km) around caldera. Several smaller cones are found on the western
and southern slopes of Sheveluch's southwestern cone. Sheveluch erupted
violently in 1854 and 1964. Sheveluch has erupted at least 28 times, its
most recent eruption occurred in 1997.
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- July 31, 1997
- The alert level at Sheveluch was raised
to indicate that an eruption is possible this week, after several explosions
sent gas plumes high above the volcano. On July 21 and 27, gas at temperatures
up to 900 degrees F (500 degrees C) rose 1000-1300 ft (300-400 m) above
the dome inside the crater. Plumes from this event were blown to the southwest.
These plumes extended about 30 miles (50 km) from the volcano. On July
22-26, gas explosions sent a plume up to 5000 ft (1500 m) over the crater.
These plumes were blown a distance of 40 miles (60 km) to the northeast.
- This information was summarized from a
report by KVERT.
-
- Recent Activity:
- Fumarolic activity was observed in January
1997.
-
- 1996:In October, fumarolic plumes reached over a half mile (1 km) in
height. On May 26th through July 26th gas and steam plumes were erupted
to heights of 160-1000 ft. (50-300 m).
-
- 1986, 1988, 1989, 1990, 1991 and 1993
eruptions occurred but we have not yet found their documentation!
-
- 1985: Ash was explosively ejected from the crater on May 26th, August
8th, September 19th and October 25th. During the September 19th eruption
an ash cloud 2 1/2 miles (4 km) high was formed.
-
- 1984: On May 22nd a single ash cloud was ejected over a half mile (1
km) into the air. This eruption made no visible changes in the lava dome's
appearance.
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- 1980: In August a lava dome was observed growing in Sheveluch's summit
crater. The dome continued to grow throughout 1981 reaching a height of
590 ft.(180m). During this time a gas and ash vent formed on the dome's
southeastern slope and avalanche debris built up and extended 2,300 ft.(700m)
down the dome's southern slope.
-
- 1964: On November 12, a very short, powerful blast occurred, this Bezymianny
type of eruption lasted for only a hour. It had been preceded by a lengthy
increase in seismic activity. Then at 7.07 am when the strongest earthquakes
occurred, they were followed by a huge explosion that created a large
crater with a 1.25 mile (2km) diameter. This eruption destroyed Crater
Top's five large domes leaving only remnants of the largest dome "Fourth
top" and a huge south opening explosion crater. The northern wall
of this new crater reaches a height of 2,300ft.(700m) A 6-10 mile high
(10-15 km) ash cloud was ejected above the Kamchatka river valley. Lightning
shot through the center of the cloud and thunder was heard in the villages
of Kliuchi and Krakhtcha. The cloud moved to the southeast and created
conditions of zero visibility and electrical discharging phenomena in
the village of Ust-Kamchatsk. About an inch (3 cm) of ash was deposited
in three hours. The eruption had deposited a flow of pyroclastic material
up to 6 miles (10km) south of Sheveluch. This flow reached a maximum thinkess
of 160 ft.(50m) at a distance of 3-6 miles (5-10km) and had a maximum
length of 11 miles (18 km). Huge blocks of glacial ice were ejected more
than 6 miles (10 km) from their parent glacier.
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- 1944-50: The first explosion of this eruption occurred on December
23rd, over time the explosions became more frequent and energetic. Throughout
the later part of 1945 ash was ejected to heights of over 3 miles (5-6km).
Early in 1946 an extrusive dome named "Suelich" started to form;
by the end of that year it had grown over 1,300 ft.(400m), and continued
to grow another 300 to 500 ft.(100-150m) the next year. On April 6th,
1950, Suelich began to erupt explosively from its summit, but shortly
thereafter died down in activity. At this time, Suelich was ~2,000 ft.
tall (600m) and had a diameter of over a half mile (1 km) at its base.
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- 1928-29: A fairly weak and poorly documented eruption occurred.
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- 1905: Another poorly docummented eruption might have occurred.
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- 1897: It is believed that Sheveluch's central dome was formed during
this eruption.
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- 1879-83: A dome was formed within the crater walls but was destroyed
in an explosion.
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- 1854: For over 150 years Sheveluch was silent, but on February 18th
it erupted violently, nearly destroying "Fourth Top". From this
explosion a 1.25 mile (2 km) diameter crater was created as pyroclastic
flows extended out to the south and west. Some of these flows are almost
unbeliveably long - up to 65 miles (90 km). This eruption is thought to
have been more powerful than the 1964 eruption and most likely was larger
than
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