ALASKA VOLCANO OBSERVATORY WEEKLY UPDATE
U.S. Geological Survey
Friday, June 6, 2014, 1:27 PM AKDT (Friday, June 6, 2014, 21:27 UTC)

PAVLOF VOLCANO (VNUM #312030)
55°25'2" N 161°53'37" W, Summit Elevation 8261 ft (2518 m)
Current Volcano Alert Level: WATCH
Current Aviation Color Code: ORANGE

The eruption of Pavlof Volcano that began late on the evening of May 30 is continuing, although the level of activity has declined appreciably over the past 24 hours. Elevated surface temperatures at the summit of the volcano persist in satellite images indicative of continued effusion of lava, cooling lava flows and spatter, or both. At present, ash emissions appear to be greatly reduced and no ash or steam plumes have been evident in satellite images since June 4, although cloud cover has obscured the volcano since Wednesday, June 4. Significant emissions of SO2 gas have been observed in satellite images beginning several days into the eruption.

Beginning May 31, the level of activity escalated gradually and the volcano was producing a nearly continuous ash plume from June 2-4, and ash and steam plumes up to 30,000 feet were observed in clear satellite and web camera images. AVO raised the Aviation Color Code and Volcano Alert Level to RED/Warning on the afternoon of Monday, June 2 as a result of rapidly increasing seismicity and observations of ash plumes above 20,000 feet. This level of eruptive activity persisted for about 6 hours before beginning to decline back to earlier levels, and soon after AVO reduced the status to ORANGE/Watch on Tuesday, June 3, 2014, at 5:54 PM AKDT (01:54 UTC June 4) where it presently remains. Observations this morning indicate a pause in eruptive activity and greatly diminished ash emissions and lava production at the vent.

The largest ash and steam plumes generated thus far have reached about 30,000 ft ASL and have extended about 50-60 mi (80-90 km) downwind of the volcano. AVO has received no reports of significant ash fallout on communities near the volcano, including Sand Point, King Cove, Nelson Lagoon, or Cold Bay, although trace amounts of ash may have reached these areas on occasion. Significant ash fallout has been limited to the immediate area surrounding the volcano. Seismic data from stations on the north flank of the volcano indicate that volcanic mudflows (lahars) have been occurring intermittently and these are likely causing minor flooding in the main drainages on the north flank of the volcano. The extent of inundation associated with these flows is not yet known.

Pavlof Volcano is experiencing a typical Strombolian eruption, characterized by lava fountaining, minor explosions, and the accumulation of spatter on the upper north flank of the volcano. Accumulations of spatter have occasionally built up and collapsed, forming hot, ashy, particle-rich flows that generate high-rising steam plumes on the lower north flank of the volcano. As these flows interact with ice and snow on the volcano, they produce meltwater and steam plumes. Spatter-fed lava flows also are likely forming.

Pavlof is one of the most frequently active volcanoes in Alaska and it has had eruptions lasting as short as 2 days and as long as 2 years. At this point in the current eruption it is not known if or when significant eruptive activity will resume. The activity could abruptly intensify with increased lava fountaining, spatter accumulation, and generation of ash plumes with little or no warning. Even if ash plumes are not significantly above 20,000 ft ASL the amount of ash produced could interfere with local air travel and local communities could receive a trace dusting of ash. Significant ash fall on local communities is not expected to occur given the level of eruptive activity observed thus far.


Pavlof Volcano is a snow- and ice-covered stratovolcano located on the southwestern end of the Alaska Peninsula about 953 km (592 mi) southwest of Anchorage. The volcano is about 7 km (4.4 mi) in diameter and has active vents on the north and east sides close to the summit. With over 40 historic eruptions, it is one of the most consistently active volcanoes in the Aleutian arc. Eruptive activity is generally characterized by sporadic Strombolian lava fountaining continuing for a several-month period. Ash plumes as high as 49,000 ft ASL have been generated by past eruptions of Pavlof, and during the 2013 eruption, ash plumes as high as 27,000 feet above sea level extending as much as 500 km (310 mi) beyond the volcano were generated. The nearest community, Cold Bay, is located 60 km (37 miles) to the southwest of Pavlof.

SHISHALDIN VOLCANO (VNUM #311360)
54°45'19" N 163°58'16" W, Summit Elevation 9373 ft (2857 m)
Current Volcano Alert Level: WATCH
Current Aviation Color Code: ORANGE

The Low-level eruptive activity at Shishaldin continued during the past week. Elevated surface temperatures were observed almost daily in satellite images, and when the web camera view was clear, summit steam emissions were visible. The local seismic network detected only a few events from explosions deep in the summit crater.

Shishaldin volcano, located near the center of Unimak Island in the eastern Aleutian Islands, is a spectacular symmetric cone with a base diameter of approximately 16 km (10 mi). A small summit crater typically emits a noticeable steam plume with occasional small amounts of ash. Shishaldin is one of the most active volcanoes in the Aleutian volcanic arc, with at least 54 episodes of unrest including over 24 confirmed eruptions since 1775. Most of Shishaldin's eruptions have produced small ash and steam plumes, although a recent eruption in April-May 1999 generated an ash column that reached a height of 45,000 ft above sea level.

CLEVELAND VOLCANO (VNUM #311240)
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 activity was observed this week at Cleveland until the late evening hours of Wednesday June 5, 2014. An explosion occurred at volcano at about 10:08 AKDT (06:08 UTC) and was detected on the Dillingham acoutstic infrasound array and at seismic stations at Korovin Volcano; AVO has no seismic instruments on Cleveland or Chuginadak Island. The event appears to have been of short duration and with similar amplitude to previous explosions at Cleveland. A small, detached cloud with a weak ash signal was observed in a satellite image at 00:04 AKDT (08:04 UTC) June 5. The cloud was at an altitude of about 25,000 ft. ASL and about 140 km (86 mi) southwest of the volcano, and rapidly dissipated. The last previous explosion at Cleveland occurred in early March, 2014.

Cleveland volcano forms the western half of Chuginadak Island, a remote and uninhabited island in the east central Aleutians. The volcano is located about 75 km (45 mi) west of the community of Nikolski, and 1500 km (940 mi) southwest of Anchorage. The most recent significant eruption began in February, 2001 and produced 3 explosive events that generated ash clouds as high as 39,000 ft above sea level. The 2001 eruption also produced a lava flow and hot avalanche that reached the sea.

VENIAMINOF VOLCANO (VNUM #312070)
56°11'52" N 159°23'35" W, Summit Elevation 8225 ft (2507 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW

Seismicity remained slightly above background this week. Weakly elevated surface temperatures were observed intermittently in satellite imagery consistent with the cooling lava flows. Minor steam emissions from the intracaldera cone were occasionally visible in clear web camera views.

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 cubic km, 77 cubic mi) 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 Strombolian eruptions producing lava fountans and minor emissions of ash and gas from the main intracaldera cone. During the 1993-95 activity, a small lava flow was extruded into the ice field producing a melt pit. Minor ash-producing explosions occurred nearly annually between 2002 and 2008. Previous historical eruptions have produced ash plumes that reached 20,000 ft above sea level (1939 and 1956) and ash fallout that blanketed areas within about 40 km (25 mi) of the volcano (1939).

OTHER ALASKA VOLCANOES

Other Alaska volcanoes show no signs of significant unrest: http://www.avo.alaska.edu/activity/

AVO scientists conduct daily checks of earthquake activity at all seismically-monitored volcanoes, examine web camera and satellite images for evidence of airborne ash and elevated surface temperatures, and consult other monitoring data as needed.

For definitions of Aviation Color Codes and Volcano Alert Levels, see: http://www.avo.alaska.edu/color_codes.php

FOR MORE INFORMATION ON ALASKA VOLCANOES: http://www.avo.alaska.edu

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CONTACT INFORMATION:

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

Jeff Freymueller, Coordinating Scientist, UAFGI
jeff.freymueller@gi.alaska.edu (907) 322-4085

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.

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