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ALASKA VOLCANO OBSERVATORY WEEKLY UPDATE
U.S. Geological Survey
Friday, June 21, 2013, 12:56 PM AKDT (Friday, June 21, 2013, 20:56 UTC)
55°25'2" N 161°53'37" W,
Summit Elevation 8261 ft (2518 m)
Current Volcano Alert Level: WATCH
Current Aviation Color Code: ORANGE
Eruptive activity at Pavlof continued over the past week. Persistent elevated surface temperatures consistent with lava effusion were observed in satellite images, and minor ash plumes below 20,000 ft were generated through most of the week. There were no reports of ash fall on local communities. On June 18, small discreet ash puffs were seen in images of the volcano from a web camera located in Cold Bay. Refer to the NWS Alaska Aviation Weather Unit (http://aawu.arh.noaa.gov/) for updates on SIGMETs related to ash emissions.
Volcanic tremor and small explosions continue to be detected on the compromised but functional local seismic network. The volcano is obscured by weather in recent web camera images.
Previous eruptions of Pavlof Volcano have lasted for weeks, months or years and often exhibit fluctuating levels of activity and it is not uncommon for the volcano to enter short periods of repose followed by vigorous ash emissions, lava fountaining, and lahar generation. Occasionally past eruptions have generated vigorous ash emissions and clouds that reached 30,000-50,000 ft. above sea level. We expect this eruption to proceed in a manner similar to previous eruptions.
Eruptive activity at Pavlof could increase with little to no warning.
Pavlof volcano is located on the southwestern end of the Alaska Peninsula. Pavlof is a stratovolcano which rises to an elevation of 8262 feet. With almost 40 historic eruptions, it is one of the most consistently active volcanos in the Aleutian arc. Eruptive activity is generally characterized by sporadic strombolian fountaining continuing for a several-month period. The community of Cold Bay is located 60 km (37 miles) to the southwest of Pavlof.
56°11'52" N 159°23'35" W,
Summit Elevation 8225 ft (2507 m)
Current Volcano Alert Level: WATCH
Current Aviation Color Code: ORANGE
The eruption of Mount Veniaminof volcano which began on June 13 continues. Satellite images showed intense elevated surface temperatures consistent with lava effusion at the cinder cone inside the caldera throughout the week. Seismic tremor continued throughout the week. On June 18, small, short lived ash bursts rising to less than 15,000 ft were seen in clear images from the FAA web camera in Perryville. On June 19, residents in Sandy River reported seeing ash bursts from the volcano rising to 10,000-15,000 ASL and blowing to the northeast. The volcano was obscured by weather in web camera images for the rest of the week and it is possible that ash bursts continue and are undetected. Refer to the NWS Alaska Aviation Weather Unit (http://aawu.arh.noaa.gov/) for updates on SIGMETs related to ash emissions.
Recent satellite images continue to show intense elevated surface temperatures at the cinder cone inside the caldera and seismic tremor continues. The seismic network at Veniaminof is not fully functional compared to that operating during the last eruption (2005), so the accuracy with which we can interpret ongoing seismicity is diminished.
Technical problems temporarily disabled the real-time seismic data feeds from Veniaminof on Wednesday, June 19, and were resolved within a few hours, restoring the data stream.
Recent eruptions of Veniaminof volcano have all occurred from vents located on the cinder cone inside the caldera and were characterized by brief bursts of ash emission and small explosions. Ash plumes associated with this type of activity are typically diffuse and generally do not reach more than 20,000 feet above sea level. Ash fallout is typically limited to the flanks of the volcano. Minor emissions of steam and ash may persist for for weeks to months. The current lava flow is expected to remain within the confines of the caldera. There is a possibility that activity at the volcano could increase with little to no warning.
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 elevated surface temperatures were observed in satellite images throughout the week. We have received no other reports of activity at the volcano.
Sudden explosions of blocks and ash are still possible with little or no warning. Ash clouds, if produced, could exceed 20,000 feet above sea level. If a large ash-producing event occurs, nearby seismic, infrasound, or volcanic lightning networks should alert AVO staff quickly. However, for some events, a delay of several hours is possible. Cleveland volcano does not have a local seismic network and is monitored using only distant seismic and infrasound instruments and satellite data.
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, 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
Jessica Larsen, Acting Coordinating Scientist, UAFGI
email@example.com (907) 474-7992
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.