ALASKA VOLCANO OBSERVATORY WEEKLY UPDATE
U.S. Geological Survey
Friday, August 30, 2013, 11:18 AM AKDT (Friday, August 30, 2013, 19:18 UTC)
56°11'52" N 159°23'35" W,
Summit Elevation 8225 ft (2507 m)
Current Volcano Alert Level: WATCH
Current Aviation Color Code: ORANGE
Increased seismicity, characterized by elevated levels of continuous tremor, lava fountaining, and ash emissions as high as 15,000 to 20,000 feet above sea level have been occurring at Veniaminof Volcano this morning. The ongoing episode of activity is some of the strongest unrest detected at the volcano so far. Although the activity at present is primarily lava fountaining and moderate ash emission, it is possible, but not certain, that conditions may continue to escalate, and higher rising, more ash rich plumes may be generated.
Throughout the past week, the volcano has experienced fluctuating levels of seismic activity characterized by alternating periods of relatively continuous low-level tremor and discreet bursts of higher amplitude tremor. Amounts of lava effusion and ash emission have also fluctuated slightly throughout the week, until this morning when ash production and lava fountaining have intensified.
The ash plume associated with the current level of unrest is moving in a southeasterly direction and has resulted in trace amounts of ash fall on areas downwind of the volcano including Perryville. Trace amounts of ash fall on other communities southeast of the volcano, including Chignik Bay, Chignik Lagoon, and Chignik Lake is possible. Ash fall amounts are not expected to be significant and likely will be less than 1/16 inch, although areas within 1-2 miles of the intracaldera cone could receive thicker amounts of ash fall. Information about volcanic ash and its potential effects can be found on the AVO web page (www.avo.alaska.edu).
AVO is monitoring the volcano closely and will provide additional information about the ongoing eruption as the situation warrants.
Mount Veniaminof volcano is an andesitic stratovolcano with an ice-filled 10-km diameter summit caldera located on the Alaska Peninsula, 775 km (480 mi) southwest of Anchorage and 35 km (22 mi) north of Perryville. Veniaminof is one of the largest (~ 300 km3) and most active volcanic centers in the Aleutian Arc and has erupted at least 13 times in the past 200 years. Recent significant eruptions of the volcano occurred in 1993-95 and 2005. Both were moderate Strombolian eruptions producing intermittent low-level jets of incandescent lava fragments, and low-level emissions of steam and ash from the main intracaldera cone. During the 1993-95 activity, a small lava flow was extruded into the summit caldera ice field producing an ice pit. Minor ash-producing explosions occurred in 2002, 2004, early 2005, November 2006, and February 2008. Previous historical eruptions have produced ash plumes that reached 6,000 m (20,000 ft) above sea level and ash fallout that blanketed areas within about 40 km (25 mi) of the volcano.
52°49'20" N 169°56'42" W,
Summit Elevation 5676 ft (1730 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW
No anomalous activity at Cleveland Volcano was observed in satellite imagery during the past week. Possible faint thermal features were observed in a few satellite images throughout the past week, but no persistent thermal signals at the summit of the volcano were evident throughout the week. AVO has received no other reports of activity at the volcano.
Cleveland volcano forms the western half of Chuginadak Island, a remote and uninhabited island in the east central Aleutians. It is located about 75 km (45 mi.) west of the community of Nikolski, and 1500 km (940 mi.) southwest of Anchorage. The volcano's most recent significant eruption began in February, 2001 and it produced 3 explosive events that produced ash clouds as high as 12 km (39,000 ft) above sea level. The 2001 eruption also produced a rubbly lava flow and hot avalanche that reached the sea. The most recent minor ash emissions were observed in November 2012.
OTHER ALASKA VOLCANOES
Seismic activity is monitored in real time at 29 volcanoes in Alaska. Satellite images of all Alaskan volcanoes are analyzed daily for evidence of ash plumes and elevated surface temperatures. Some volcanoes may currently display anomalous behavior but are not considered to be at a dangerous level of unrest. Akutan, Aniakchak, Augustine, Dutton, Fisher, Fourpeaked, Gareloi, Great Sitkin, Griggs, Iliamna, Isanotski, Kanaga, Katmai, Mageik, Makushin, Martin, Novarupta, Okmok, Pavlof, Redoubt, Shishaldin, Snowy, Spurr, Tanaga, Trident, Ugashik-Peulik, Ukinrek Maars, and Westdahl volcanoes are in color code GREEN
and volcano alert level Normal. All are at or near normal levels of background seismicity. AVO did not detect ash plumes or significant elevated surface temperatures in the vicinity of any of these volcanoes.
Please see http://www.avo.alaska.edu/color_codes.php
for complete definitions of Aviation color codes and Volcano alert levels.
VOLCANO INFORMATION ON THE INTERNET: http://www.avo.alaska.edu
RECORDING ON THE STATUS OF ALASKA'S VOLCANOES (907) 786-7478
John Power, Scientist-in-Charge, USGS
firstname.lastname@example.org (907) 786-7497
Jeff Freymueller, Coordinating Scientist, UAFGI
email@example.com (907) 378-7556
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.