ALASKA VOLCANO OBSERVATORY DAILY UPDATE
U.S. Geological Survey
Wednesday, July 19, 2023, 3:21 PM AKDT (Wednesday, July 19, 2023, 23:21 UTC)
Lava has continued to erupt from the summit crater of Shishaldin over the last day. This activity was reflected in satellite observations of strongly elevated surface temperatures at the summit. Seismicity is currently low. Low-level as emissions near the summit crater maybe occuring with current activity, and larger explosions from Shishaldin can occur with little warning.
High resolution satellite images from mid-day yesterday document deposits from the period of increased activity earlier that morning. Ash deposits tracked southwest from the vent and from pyroclastic deposits on the north, east, and south flanks. Pyroclastic deposits from the eruption to date have extended as far as 1.9 miles (3 km) from the vent. Mudflows triggered by the eruption have extended further down the flanks.
Shishaldin is monitored by local seismic and infrasound sensors, web cameras, and a telemetered geodetic network. The local monitoring network is partially impaired, therefore AVO is also using nearby geophysical networks, satellite data and regional infrasound and lighting data.
Slow eruption of lava continues at Great Sitkin Volcano, where it is producing a thick lava flow within the summit crater. Several local earthquakes were detected over the past day. Cloudy weather conditions prevented clear views of the volcano in satellite and web camera imagery.
An eruption of lava began at Great Sitkin Volcano in July 2021 and has continued to slowly erupt since, but no explosive events have occurred. An explosive event occurred in May 2021, before the current eruption of lava. The volcano is monitored by local seismic and infrasound sensors, satellite data, webcams, and regional infrasound and lightning networks.
There has been an increase in the number of earthquakes observed near Cleveland volcano over the past week, prompting an increase in the Aviation Color Code and Volcano Alert Level to YELLOW and ADVISORY. These earthquakes continued over the last day, along with steaming and gas emissions from the summit of Mount Cleveland seen in clear web camera images.
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. 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, lightning, and satellite data.
Seismic activity near Trident Volcano remained elevated over the past 24 hours. No volcanic activity or unrest was observed in clear satellite and web camera images over the past day.
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.
Seismicity was low at Aniakchak volcano over the past day with 3 local earthquakes detected. No activity was observed in partly cloudy satellite and web camera views over the past 24 hours.
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.
AVO currently monitors Aniakchak with satellite remote sensing data, regional infrasound and lightning networks and several regional seismometers. The local seismic network has been struggling with power issues during the past week.
A few single local earthquake was detected over the last day at Semisopochnoi Island. Clouds obscured all satellite and web camera images.
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 recent periods of eruption since 2018. 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.
Kristi Wallace, Acting Scientist-in-Charge, USGS firstname.lastname@example.org (907) 786-7497
Pavel Izbekov, Acting Coordinating Scientist, UAFGI email@example.com (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.
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