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AVO/USGS Volcanic Activity Notice

Volcano: Cleveland (CAVW #1101-24-)

Current Volcano Alert Level: WATCH
Previous Volcano Alert Level: ADVISORY

Current Aviation Color Code: ORANGE
Previous Aviation Color Code: YELLOW

Issued: Tuesday, September 6, 2011, 4:08 PM AKDT (20110907/0008Z)
Source: Alaska Volcano Observatory
Notice Number: 2011/A5
Location: N 52 deg 49 min W 169 deg 56 min
Elevation: 5676 ft (1730 m)
Area: Aleutians Alaska

Volcanic Activity Summary: Observations of Cleveland Volcano from Tuesday September 6, 2011 show that the small lava dome in the summit crater has resumed growth and now fills the floor of the crater. In response, AVO is raising the Aviation Color Code to Orange and the Alert Level to Watch.

A persistent thermal anomaly has been observed since September 3, probably marking the timing of resumed lava dome growth. The size of the dome as of August 30 when it appeared to have stopped growing was approximately 80 meters (262 feet)in diameter. The current dome is approximately 120 meters (394 feet) in diameter. If dome growth continues, lava flows onto the flanks of the volcano may develop but would not be hazardous to aviation. The presence of the lava dome increases the possibility of an explosive eruption, but does not necessarily indicate that one will occur. Short-lived explosions could produce an ash cloud that exceeds 20,000 ft above sea level. These events can occur without warning and may go undetected in satellite imagery for hours.

Without a real-time seismic network on the volcano, AVO is unable to track local earthquake activity related to volcanic unrest, provide forecasts of eruptive activity, or confirmation of explosive, ash-producing events. AVO will continue to monitor the volcano using satellite data as it becomes available.

Recent Observations:
[Lava flow/dome] 120 meter (394 feet) diameter dome fills the floor of the summit crater as of September 6, 2011.
[Volcanic cloud height] Unknown
[Other volcanic cloud information] Unknown

Contacts: John Power, Scientist-in-Charge, USGS
jpower@usgs.gov (907) 786-7497

Steve McNutt, Coordinating Scientist, UAF
steve@giseis.alaska.edu (907) 474-7131

Next Notice: A new VAN will be issued if conditions change significantly or alert levels are modified. While a VAN is in effect, regularly scheduled updates are posted at
http://www.avo.alaska.edu

The Alaska Volcano Observatory is a cooperative program of the U.S. Geological Survey, the University of Alaska Fairbanks Geophysical Institute, and the Alaska Division of Geological and Geophysical Surveys.
(1) VOLCANO OBSERVATORY NOTICE FOR AVIATION (VONA)
(2) Issued:(20110907/0008Z)
(3) Volcano:Cleveland (CAVW# 1101-24-)
(4) Current Color Code:ORANGE
(5) Previous Color Code:yellow
(6) Source:Alaska Volcano Observatory
(7) Notice Number:2011/A5
(8) Volcano Location:N 52 deg 49 min W 169 deg 56 min
(9) Area:Aleutians Alaska
(10) Summit Elevation:5676 ft (1730 m)
(11) Volcanic Activity Summary:Observations of Cleveland Volcano from Tuesday September 6, 2011 show that the small lava dome in the summit crater has resumed growth and now fills the floor of the crater. In response, AVO is raising the Aviation Color Code to Orange and the Alert Level to Watch.

A persistent thermal anomaly has been observed since September 3, probably marking the timing of resumed lava dome growth. The size of the dome as of August 30 when it appeared to have stopped growing was approximately 80 meters (262 feet)in diameter. The current dome is approximately 120 meters (394 feet) in diameter. If dome growth continues, lava flows onto the flanks of the volcano may develop but would not be hazardous to aviation. The presence of the lava dome increases the possibility of an explosive eruption, but does not necessarily indicate that one will occur. Short-lived explosions could produce an ash cloud that exceeds 20,000 ft above sea level. These events can occur without warning and may go undetected in satellite imagery for hours.

Without a real-time seismic network on the volcano, AVO is unable to track local earthquake activity related to volcanic unrest, provide forecasts of eruptive activity, or confirmation of explosive, ash-producing events. AVO will continue to monitor the volcano using satellite data as it becomes available.
(12) Volcanic cloud height:Unknown
(13) Other volcanic cloud information:Unknown
(14) Contacts:John Power, Scientist-in-Charge, USGS
jpower@usgs.gov (907) 786-7497

Steve McNutt, Coordinating Scientist, UAF
steve@giseis.alaska.edu (907) 474-7131
(15) Next Notice:A new VONA will be issued if conditions change significantly or alert levels are modified. While a VONA is in effect, regularly scheduled updates are posted at
http://www.avo.alaska.edu