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USGS Volcano Notice - DOI-USGS-AVO-2023-04-22T12:22:36-08:00
ALASKA VOLCANO OBSERVATORY DAILY UPDATE
U.S. Geological Survey
Saturday, April 22, 2023, 12:32 PM AKDT (Saturday, April 22, 2023, 20:32 UTC)
SEMISOPOCHNOI (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
Bursts of tremor were detected at Semisopochnoi volcano over the past 24 hours in seismic data. No evidence for explosive activity seen in infrasound data. Nothing significant observed in cloudy satellite images and webcam views.
Small eruptions producing minor ash deposits within the vicinity of the active north crater of Mount Young and ash clouds usually under 10,000 ft (3 km) above sea level have characterized the recent periods of activity. Additional ash-producing events could occur again with little warning.
Semisopochnoi volcano is monitored by local seismic and infrasound sensors, satellite data, webcams, and regional infrasound and lightning networks.
GREAT SITKIN (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
Lava continues to erupt at the summit of Great Sitkin Volcano, producing a thick lava flow within the summit crater. Nothing signifiant was seen in cloudy satellite images over the past day. Webcam views were also obscured by clouds. Seismic activity was low and characterized by occasional small earthquakes.
Great Sitkin Volcano is monitored by local seismic and infrasound sensors, satellite data, webcams, and regional infrasound and lightning networks.
TANAGA (VNUM #311080)
51°53'2" N 178°8'35" W, Summit Elevation 5925 ft (1806 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW
Elevated earthquake activity beneath Tanaga Volcano and nearby Takawangha volcano continued over the past 24 hours, although the rate and size of the earthquakes was lower than during previous days. No eruptive activity was observed in cloudy to partly cloudy satellite observations.
Increases in seismic activity have been detected previously at Tanaga Volcano and other similar volcanoes, with no subsequent eruptions. We expect additional shallow seismicity and possibly other signs of unrest, such as gas emissions, elevated surface temperatures, and surface deformation to precede any future eruption, if one were to occur.
Tanaga Volcano and Takawangha volcano are monitored with a local seismic and infrasound network, regional infrasound and lightning detection networks, and satellite data. Takawangha volcano is about 5 miles (8 km) east of Tanaga Volcano on Tanaga Island.
TAKAWANGHA (VNUM #311090)
51°52'1" N 178°1'37" W, Summit Elevation 4754 ft (1449 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW
Elevated earthquake activity beneath Takawangha volcano and nearby Tanaga Volcano continued over the past 24 hours, although the rate and size of the earthquakes was lower than during previous days. No eruptive activity was observed in cloudy to partly cloudy satellite observations.
Increases in seismic activity have been detected previously at Takawangha volcano and other similar volcanoes, with no subsequent eruptions. We expect additional shallow seismicity and possibly other signs of unrest, such as gas emissions, elevated surface temperatures, and surface deformation to precede any future eruption, if one were to occur.
Takawangha volcano and Tanaga Volcano are monitored with a local seismic and infrasound network, regional infrasound and lightning detection networks, and satellite data. Tanaga Volcano is about 5 miles (8 km) west of Takawangha volcano on Tanaga Island.
ANIAKCHAK (VNUM #312090)
56°54'21" N 158°12'32" W, Summit Elevation 4400 ft (1341 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW
Earthquake activity beneath Aniakchak volcano continued over the past 24 hours. No eruptive activity was observed in clear satellite and webcam views of the volcano.
The current period of seismic unrest began in October 2022. Increases in seismic activity have been detected previously at other similar volcanoes, with no subsequent eruptions. We expect additional shallow seismicity and other signs of unrest, such as gas emissions, elevated surface temperatures, and surface deformation to precede any future eruption, if one were to occur.
AVO monitors Aniakchak with a local network, which currently consists of three functional seismometers, as well as satellite remote sensing data and regional infrasound and lightning networks.
TRIDENT (VNUM #312160)
58°14'3" N 155°6'9" W, Summit Elevation 3599 ft (1097 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW
Earthquake activity continued in the vicinity of Trident Volcano over the last 24 hours at a low rate, but above background levels. No volcanic activity was observed in clear satellite and webcam data.
The current period of seismic unrest began on August 24, 2022. Increases in seismic activity have been detected previously at Trident Volcano and other similar volcanoes, with no subsequent eruptions. We expect additional shallow seismicity and other signs of unrest, such as gas emissions, elevated surface temperatures, and surface deformation to precede any future eruption, if one were to occur.
AVO monitors Trident Volcano with a local network of seismometers, a webcam, remote sensing data, and regional infrasound and lightning networks.
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
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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) 378-5460
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.