Event Name : Shishaldin 2019
|Start:||July 12, 2019 ||Observed|
|Lava flow: ||
|Lahar, debris-flow, or mudflow: ||
|Tephra plume: ||
The Alaska Volcano Observatory raised the Aviation Color Code to YELLOW and the Alert Level to ADVISORY at Shishaldin Volcano on July 12, 2019. This change was based on increased seismic activity over the past few weeks, accompanied by elevated surface temperatures at the summit in satellite data. A pilot also observed incandescence in the summit crater during a recent overflight.
On July 23, AVO field crews observed an active lava lake and minor spattering within the summit crater during a helicopter overflight. Elevated seismic activity continues similar to the past few weeks along with consistent elevated surface temperatures in satellite images. AVO raised the Aviation Color Code and Volcano Alert Level to ORANGE/WATCH on July 24, 2019. During September, seismicity and surface temperatures decreased, and AVO lowered the Aviation Color Code and Volcano Alert Level to YELLOW/ADVISORY on September 26, 2019.
A new lava effusion event began on October 13, 2019, and AVO again raised the Aviation Color Code and Volcano Alert Level to ORANGE/WATCH. Over the next several weeks, these lava flows intermittently advanced. The summit cone partially collapsed on November 25, producing a pyroclastic flow down the northwest side of the volcano. A new lava flow was also generated. On December 12, 2019, a short-lived explosion from Shishaldin produced an ash cloud to 20,000-25,000 ft. The cloud moved west-northwest and dissipated within a couple of hours. During late December, eruptive activity continued, with lava flows, and low-level explosive activity at the summit. On January 3, 2020, beginning at about 9:30 am AKST, seismicity at the volcano began increasing over a period of several hours and eventually led to a brief period of sustained ash emission resulting in an ash cloud that reached as high as 27,000 feet above sea level according to reports from passing pilots. The ash cloud consisted of a linear, directed ash plume that extended from the volcano to the southeast at least 75 miles. The ash cloud also produced minor amounts of volcanic lightning. Seismicity then abruptly decreased.