USGS Volcano Notice - DOI-USGS-AVO-2023-08-05T13:16:28-08:00

The eruption yesterday morning produced an ash cloud the drifted to the northeast at about 26000 ft above sea level.  This drifting ash cloud could be seen in satellite data and was observed by pilots.  Seismicity remained significantly elevated until 3:00 pm AKDT (23:00 UTC) when the seismic intensity dropped sharply to slightly elevated levels.  At this time, a high level meterological cloud obscured satellite views of both the volcano and the drifting ash cloud.  Due to the decrease in seismicity, the Alaska Volcano Observatory lowered the Aviation Color Code and Alert Level to ORANGE/WATCH on Aug. 4 at 8:55 pm (Aug. 5 03:55 UTC).  Since then, seismicity has decreased in intensity to low levels.

Shishaldin has had six periods of elevated eruptive activity resulting in significant ash emission during the current eruption which started on July 12.  It is unknown how long this eruption will last, but previous eruptions of Shishaldin Volcano have lasted weeks to months with repeated cycles of activity similar to those seen in the last two weeks.

Shishaldin Volcano is monitored by local seismic and infrasound sensors, web cameras, and a telemetered geodetic network. In addition to the local monitoring network, AVO uses nearby geophysical networks, regional infrasound and lighting data, and satellite images to detect eruptions.

Slow eruption of lava continues at Great Sitkin Volcano, where it is producing a thick lava flow within the summit crater. The eastern lobe of this flow continues to advance.  Earthquake activity remains slightly elevated over the past day.  Clouds obscured views of the volcano by satellite and web camera.

The current lava flow at Great Sitkin Volcano began erupting in July 2021. No explosive events have occurred since a single event in May 2021.

The volcano is monitored by local seismic and infrasound sensors, web cameras, regional infrasound and lightning networks, and satellite data.

Seismic activity at Cleveland volcano remains low over the past day with possible tremor detected. Cloudy conditions obscured satellite and web camera views over the past day.

Episodes of lava effusion and explosions can occur without advance warning. Explosions from Mount 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 currently monitored with a five-station real-time seismic network and three nearby web cameras. Based on past events, explosive eruptions of Cleveland may occur with little or no warning. Rapid detection of an ash-producing eruption may be possible using a combination of seismic, infrasound, web camera, lightning, and satellite data.

Seismic activity near Trident Volcano remained elevated over the past day. No activity was observed in partly cloudy satellite and web camera views.  

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 and did not result in eruptions. We expect additional shallow seismicity and other signs of unrest, such as gas emissions, elevated surface temperatures, and ground movement, to precede any future eruption if one were to occur.   AVO issued an Information Statement on July 25 providing a more detailed update on the volcanic unrest at Trident Volcano and the broader Katmai volcanic cluster (https://www.avo.alaska.edu/news.php?id=1595).

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

Strong southeasterly winds in the afternoon of August 4 resuspended ash from the Aniakchak region producing an ash cloud that drifted to the northwest. This phenomenon is not the result of the recent volcanic unrest and occurs during times of high winds and dry snow-free conditions. The National Weather Service has issued a SIGMET for this low-level event and suggests that the maximum cloud height is 6,000 ft above sea level.

Seismicity remains low at Aniakchak volcano over the past day.

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 additional surface deformation to precede any future eruption, if one were to occur.

Aniakchak volcano is monitored by local seismic and infrasound sensors, web cameras, regional infrasound and lightning networks, and satellite data.

Strong southwesterly winds in the vicinity of Katmai and the Valley of Ten Thousand Smokes have picked up loose volcanic ash erupted during the 1912 Novarupta-Katmai eruption and carried it to the northwest. The National Weather Service has issued a SIGMET for this low-level event and suggests that the maximum cloud height is 6,000 ft above sea level.

This phenomenon is not the result of recent volcanic activity and occurs during times of high winds and dry snow-free conditions in the Katmai area and other young volcanic areas of Alaska. No eruption is in progress.

Resuspended volcanic ash should be considered hazardous and could be damaging to aircraft and health. For more information on volcanic ash and human health, visit the following website: http://volcanoes.usgs.gov/ash/. Official warnings about these ash resuspension events are issued by the National Weather Service: https://www.weather.gov/afc/. Forecasts of airborne ash hazard to aircraft: https://www.weather.gov/aawu/. Volcanic Ash Advisories: https://www.weather.gov/vaac/. Forecasts of ash fall: http://www.weather.gov/afc. Air quality hazards and guidance from Alaska Department of Environmental Conservation, Division of Air Quality: http://dec.alaska.gov/Applications/Air/airtoolsweb/Advisories/Index