ALASKA VOLCANO OBSERVATORY DAILY UPDATE
U.S. Geological Survey
Sunday, October 3, 2021, 11:51 AM AKDT (Sunday, October 3, 2021, 19:51 UTC)

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

Seismicity has remained elevated with intermittent bursts of activity over the past day. No explosions were detected in infrasound data. Ash clouds from explosive activity yesterday and early this morning were observed in satellite images and were under 10,000 ft above sea level and drifting N and NW . Sulfur dioxide emissions were also observed in satellite imagery.

Small eruptions producing minor ash deposits within the vicinity of the active north crater of Mount Cerberus and ash clouds usually under 10,000 feet above sea level have characterized the recent activity, which shows no signs of abating. Small explosions may continue to occur and could be difficult to detect, especially during poor weather conditions.

Semisopochnoi Island is monitored by local seismic and infrasound sensors, satellite data, web cameras, and remote infrasound and lightning networks.

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

Seismicity has remained elevated over the past day. No explosive activity was detected in regional infrasound data. Mostly cloudy conditions obscured views of the volcano by satellite and web camera. Partly clear web camera images from this morning show that recent ash deposits on the flanks of the volcano are covered by new snow.

Small explosions accompanied by low-level ash emissions could happen at any time, and are typically a hazard in the immediate vicinity of the summit. The level of unrest at Pavlof can change quickly and the progression to more significant eruptive activity can occur with little or no warning.

Pavlof Volcano is monitored by local seismic and infrasound sensors, satellite data, web cameras, and remote infrasound and lightning networks.

GREAT SITKIN VOLCANO (VNUM #311120)
52°4'35" N 176°6'39" W, Summit Elevation 5709 ft (1740 m)
Current Volcano Alert Level: WATCH
Current Aviation Color Code: ORANGE

Seismicity remains slightly elevated with small earthquakes consistent with lava effusion continuing. No explosive activity or ash emissions have been detected in seismic, infrasound, or satellite data. Elevated surface temperatures were observed in clear satellite images over the past day. Satellite images show that the dome within the summit crater currently has dimensions of about 3940 ft (1200 m) east-west and about 3280 ft (1000 m) north-south. As the dome continues to grow, lava is spilling out of breaches in the crater to the south and southwest. These lava flow lobes are roughly 985 ft (300 m) and 1150 ft (350 m) long, respectively. The lobe going to the southwest is starting to split into two drainages and there is evidence that hot debris has cascaded downslope on top of snow field around 450 m past the end of the main flow.

There is no indication of how long lava effusion will continue during the current eruption, and it is possible that explosive activity could occur with little or no warning.

Great Sitkin Volcano is monitored by local seismic and infrasound sensors, satellite data, web cameras, and remote 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

No significant seismic or infrasound activity was detected over the past day. Weakly elevated surface temperatures were observed in satellite data.

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.

When operational, Cleveland volcano is monitored by only two seismic stations, which restricts AVO's ability to precisely locate earthquakes and 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.

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:

Matt Haney, Acting Scientist-in-Charge, USGS
mhaney@usgs.gov (907) 786-7497

David Fee, Coordinating Scientist, UAF
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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