![]() ![]() 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 three weeks. Shishaldin has now had six periods of elevated eruptive activity resulting in significant ash emissions during the current eruption which started on July 12. Elevated surface temperatures were observed most days throughout the week consistent with low-level eruption or recent cooling deposits. Prior to each of these events during the week, seismic activity had remained above background. Trace to minor tephra fallout is expected to the northeast of Shishaldin. At 10:17 am AKDT (18:17 UTC), the Aviation Color Code and Volcano Alert Level/Alert Level was raised to RED/WARNING where it currently remains. Over the next hour, the height of the plume increased to 30,000 ft above sea level with the plume extending over 100 km (62 miles) to the northeast. Ash emission gradually increased and the Alaska Volcano Observatory issued a second Volcanic Activity Notice while remaining at Aviation Color Code and Volcano Alert Level ORANGE/WATCH at 9:04 am AKDT (17:04 UTC). Satellite images indicated low-level ash emissions by 5:20 am (13:20 UTC) as cloud cover cleared. Seismic activity continued to increase through the night with strongly elevated surface temperatures observed through cloud cover suggesting lava was active at the surface. There was a steady increase in seismicity throughout the day and the Alaska Volcano Observatory issued a Volcanic Activity Notice announcing the lead up to explosive activity at 5:36 pm AKDT (01:36 UTC August 4). Cloudy conditions obscured satellite and web camera observations. On August 3 at about 9:00 am AKDT (18:00 UTC), seismic activity began to increase in intensity. Overall seismic activity was low at this time, however, small explosive events consistent with low level strombolian activity were detected. On August 2, an ash plume was observed by pilots north of Shishaldin from the ground surface to 9000 ft (2.7 km) above sea level. Low-level eruption of lava confined to the summit crater as well as a short duration pause in the eruption occurred between these events. The Aviation Color Code and Volcano Alert Level was raised to RED/WARNING for this second event which is ongoing. Two episodes of elevated eruptive activity occurred at Shishaldin Volcano over the past week on August 2, and August 3-4. Geological Survey Friday, August 4, 2023, 2:57 PM AKDT (Friday, August 4, 2023, 22:57 UTC) SHISHALDIN VOLCANO ALASKA VOLCANO OBSERVATORY WEEKLY UPDATE U.S. ![]()
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