ALASKA VOLCANO OBSERVATORY WEEKLY UPDATE
U.S. Geological Survey
Friday, November 21, 2014, 12:02 PM AKST (Friday, November 21, 2014, 21:02 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

Since the explosive eruption on Saturday, November 15, activity at Pavlof has remained low. Seismicity in the form of intermittent volcanic tremor has been detected since Saturday, and satellite images show that a lava flow on the volcano's northwest flank now reaches about 7 km (4.4 miles) from the summit. It is unclear whether eruptive activity has currently paused, or whether lava effusion is occurring at a low rate.

The ash-producing eruption on November 15 lasted from mid-morning until about 7 PM AKST, and produced an ash cloud that stretched northwest over the Bering Sea for over 400 km (250 miles). Numerous pilot reports placed the top of the cloud at 30,000 to 35,000 ft asl, consistent with satellite data. No ash fall was reported in nearby communities.

Pauses of days to weeks are common during eruptive episodes at Pavlof and increased activity could occur with little warning.

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

Seismic activity in the form of intermittent volcanic tremor continues and is consistent with low-level eruptive activity. Seismic levels have increased somewhat over the past day but are still within the range of what has been observed during the current eruptive phase, which began in March 2014.

Satellite observations suggest that the current activity is confined to the area immediately around the volcano's summit vent. No ash emissions were observed in the past week. The webcam has been obscured by clouds, snow, and rain for most of the past week.

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 200-m-wide (660 ft) funnel-shaped summit crater typically emits a steam plume and 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 eruptions are relatively small, although the April-May 1999 event generated an ash column that reached 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

Low-level volcanic unrest continues at Cleveland. Weakly elevated temperatures were observed at the summit in some satellite images. When webcam views were clear, a small but steady steam plume was visible rising from the summit vent. Seismicity remains low.

Cleveland volcano forms the western portion 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 period of 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. Since then, Cleveland has been intermittently active producing small lava flows, often followed by explosions that generate small ash clouds generally below 20,000 ft above sea level. These explosions also launch debris onto the slopes of the cone producing hot pyroclastic avalanches and lahars that sometimes reach the coastline.

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

SUBSCRIBE TO VOLCANO ALERT MESSAGES by email: http://volcanoes.usgs.gov/vns/

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CONTACT INFORMATION:

John Paskievitch, Acting Scientist-in-Charge, USGS
jpaskie@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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