ALASKA VOLCANO OBSERVATORY DAILY UPDATE
U.S. Geological Survey
Monday, January 20, 2020, 12:12 PM AKST (Monday, January 20, 2020, 21:12 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

The Aviation Color Code and Alert Level for Shishaldin Volcano were raised to RED/WARNING yesterday morning (January 19) when geophysical and observational data showed that eruptive activity had begun to intensify. Eruptive activity was characterized by elevated seismicity, lava flows on the northeast and north flanks of the volcano producing meltwater lahars, and a steam and ash plume that extended up to 150 km (~90 miles) east-southeast at a height of 20,000 ft. Trace ash fall was reported in False Pass. This activity continued through the day.

Seismicity decreased abruptly to low levels at about 3:30 PM yesterday afternoon, and ash production increased at about the same time, producing an ashy plume that reached to 30,000 ft. The eruption continued to produce ash until about 10 PM last night, when activity slowed. The Aviation Color Code and Alert Level were lowered to ORANGE/WATCH shortly after midnight, when it became clear that activity had waned and an ash cloud was no longer being produced. The ash cloud that had formed earlier continued to drift east-southeast overnight as it dissipated, but was still visible some 300 km (~185 miles) offshore this morning.

Elevated surface temperatures are still apparent in satellite images this morning. Webcam images captured after sunrise of the southeast side of the volcano show a weak steam plume at the summit, new tephra and (or) lava deposited on the upper flanks of the cone, and a dusting of ash on the snow across the entire area.

Shishaldin is monitored by local seismic and infrasound sensors, satellite data, web cameras, 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

No unusual activity was observed in seismic data over the past day. Elevated surface temperatures were observed in satellite views, and a weak steam plume from the volcano's summit was seen in web camera views.

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.

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

Elevated surface temperatures were seen in satellite images over the past day. Seismicity remains elevated but has not changed significantly over the past several days.

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.

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


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

No activity was detected in seismic data, satellite data, or other geophysical monitoring data over the past day.

Semisopochnoi is monitored by local seismic sensors, satellite data and distant lightning networks. An infrasound array on Adak Island may detect explosive emissions from Semisopochnoi with a slight delay (approximately 13 minutes) if atmospheric conditions permit.

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/

FOLLOW AVO ON FACEBOOK: https://facebook.com/alaska.avo

FOLLOW AVO ON TWITTER: https://twitter.com/alaska_avo

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.

---