ALASKA VOLCANO OBSERVATORY DAILY UPDATE
U.S. Geological Survey
Thursday, November 7, 2019, 11:29 AM AKST (Thursday, November 7, 2019, 20:29 UTC)

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

A low-level eruption continues at Shishaldin. Seismic tremor has been very low over the past day, with no episodes of tremor and just a few discrete events. This suggests that eruptive activity may have subsided and/or paused. Satellite and web camera observations were mostly obscured by clouds over the past day but elevated surface temperatures in the summit crater were observed during a brief period of clear weather. These observations are consistent with elevated unrest, but active lava effusion is less likely to be occurring. No significant ash emissions observed in satellite or infrasound data, although there may have been brief periods of minor ash emissions in the immediate vicinity of the summit crater.

Shishaldin is monitored by local seismic and infrasound sensors, satellite data, a web camera, a telemetered geodetic network, and distant infrasound and lightning networks.

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

Robust steaming from the summit crater was observed in satellite and web camera data yesterday afternoon. The water-rich plume extended for about 25 km (16 miles) from the volcano, rising several hundred meters (~500 ft) above the summit. Weakly elevated surface temperatures were observed in satellite data, but thermal emission were likely masked by the steam emissions. Steaming is relatively common at Cleveland and does not necessarily indicate an increase in unrest. No activity was observed in the local seismic or infrasound data at Cleveland over the past day.

Episodes of lava effusion and explosions can occur without advance warning. Explosions from Cleveland are normally short duration and only present a hazard to aviation in the immediate vicinity of the volcano. Larger explosions that present a more widespread hazard to aviation are possible, but are less likely and occur less frequently.

Cleveland volcano is monitored by only two seismic stations, which restricts AVO's ability to detect precursory unrest that may lead to an explosive eruption. Rapid detection of an ash-producing eruption may be possible using a combination of seismic, infrasound, lightning, and satellite data.

SEMISOPOCHNOI VOLCANO (VNUM #311060)
51°55'44" N 179°35'52" E, Summit Elevation 2625 ft (800 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW

Seismicity remains low. No eruptive activity has been detected by regional infrasound data, and no anomalous activity was observed in mostly cloudy satellite data over the past day.

Semisopochnoi is monitored with an on-island seismic network and remotely by satellite and lightning sensors. An infrasound array on Adak Island may detect explosive emissions from Semisopochnoi with a slight delay (approximately 13 minutes) if atmospheric conditions permit.

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

The Aviation Color Code was reduced to GREEN and the Volcano Alert Level to NORMAL earlier today. Pavlof is at background levels of activity.

The level of unrest at Pavlof can change quickly and the progression to eruptive activity can occur with little or no warning. We continue to monitor Pavlof closely and will provide any new information about the status of the volcano when or if it becomes available.

OTHER ALASKA VOLCANOES

Information on all Alaska volcanoes is available at : http://www.avo.alaska.edu.

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

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

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CONTACT INFORMATION:

Michelle Coombs, Scientist-in-Charge, USGS
mcoombs@usgs.gov (907) 786-7497

David Fee, Coordinating Scientist, UAFGI
dfee1@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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