Active volcanoes / Aktive vulkaner:
Cleveland, Alaska

Mt. Cleveland is a stratovolcano that comprises the entire western half of Chuginadak Island, 40 km west of Umnak.
Distinctively conical and symmetrical in form, Cleveland is about 8.5 km in diameter and is joined to the rugged,
though lower, eastern half of the island by a low, narrow strip of land. Sekora (1973) reports that this strip is
dotted with "lava flow, cinder, and ash patches, and conical hills.

Although it is the tallest member of the Four Mountains group, Mt. Cleveland is reported to lose snow more rapidly
than neighboring peaks presumably from anomalous heat generation Hot springs were noted at the base of a volcano
on Chuginadak Island in the 1800's .

Like many other Aleutian volcanoes, the lower flanks of Mt. Cleveland up to about the 300 m elevation are more
irregular and dissected than the upper flanks. The cones on the eastern half of Chuginadak Island are dissected by
broad valleys presumably eroded in part by glaciers; in contrast, the upper cone of Mt. Cleveland is virtually undissected.

Wednesday, February 1st, 2012
Renewed eruptive activity of Cleveland Volcano has been observed in satellite data, and AVO is raising the Aviation
Color Code to Orange and the Alert Level to Watch. A new lava dome has been observed in the summit crater,
and as of 30 January 2012 was approximately 40 meters (130 feet) in diameter. There have been no observations
of ash emissions or explosive activity during this current lava eruption.

The lava dome that formed throughout the fall-winter of 2011 was largely removed by the explosive activity on 25
and 29 December, 2011. It remains possible for intermittent, sudden explosions of blocks and ash to occur at any time,
and ash clouds exceeding 20,000 feet above sea level may develop. Such explosions and their associated ash clouds
may go undetected in satellite imagery for hours.

Friday, December 30th, 2011

The Volcano Cleveland has erupted violently early on Thursday, spouting an ash cloud 15,000 feet (4,570 metres) into
the sky and prompting an air-traffic alert. As of 1445 UTC the ash cloud was approximately 80 KM/50 miles
moving ESE from the volcano. Based on the presence of an ash cloud, AVO has raised the aviation color code
at Cleveland Volcano to ORANGE and alert level WATCH.

Ash from the 5,676-foot (1,730 metre) volcano is considered potentially dangerous to aircraft because Cleveland's peak lies directly below commercial flight paths between Asia and North America.

Thursday's explosion, captured by satellite imagery, likely stemmed from a gradual buildup of pressure
during months of intermittent low-level eruptions.
See Spurr volcano and Aviation-page

Wednesday, December 21st, 2011
Whether intermittent lava effusion in the summit crater of Cleveland has ceased or has merely paused is
not certain. Effusion could resume at any time and send lava over the crater rim and down the steep flanks
of the volcano. Such lava flows might collapse and produce avalanches of hot debris that reach the sea and
may be accompanied by small ash clouds.

Sudden explosions and ash emission could also occur, and ash clouds exceeding 20,000 feet above sea
level may develop.
See our WEB-camera here.

September 14th, 2010
During the week-end, Cleveland volcano sent up an ash- and vapourcloud about 7.000 m in the air.
This is, however, not abnormal, as according to AVO, it is known to have about 6 such eruptions during the year. Rest of the year it lets out smaller clouds almost regularly.
There are no seismic equipment at the volcano, so scientists are uncertain what is going on inside.
Cloud are normally only reported via satellite photos or from aircraft and fishingvessels in the area.

See our WEB-camera here.

March 20th, 2001

An explosive eruption began at . 00.30 last night.. According to satelite-observations at 03:30 UTC, two clouds of
ash going from the volcano, one eastward 185 km, the other wouth 200km. Both clouds about 10.000m asl.

photo by Dr. Cathy Cahill.

1944-eruption had a 2 days explosive eruption from the main crater, with lavaflows as well as tephra. Strong quakes were also registered in connection with the eruptions.
A cloud of ash and vapour was observed up to 6.000 m asl, and the lavaflow reached 5 km away from the crater.
"Bombs" as large as cars, were throuwn over large areas, and 1 person who came to close, was killed. All others on the island at that time, US Army Air Force personel, were evacuated, and the island was uninhabited for the rest of the war.

 AVO Alaska, Introduction to Cleveland Volcano


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