Description: From Dixon and others, 2020: "Shishaldin Volcano did not erupt in 2017, but volcanic unrest in December resulted in an elevated Aviation Color Code and Volcano Alert Level of YELLOW and ADVISORY, respectively, for much of the month. On April 20, AVO received a pilot report of an ash rich plume. Web-camera images confirmed the plume was composed of gas with no evidence of ash. Gas plumes are common at Shishaldin Volcano, and occasional reports of gas plumes and increased low-frequency seismic events were reported in AVO’s internal logs for most of 2017.
"In the last week of October, AVO noted elevated surface temperatures at the summit of Shishaldin Volcano. Throughout November, AVO observed increased low-frequency seismicity likely to be associated with small explosions. At the end of November, these explosions were being recorded on the infrasound array at Sand Point, Alaska, 230 km (140 mi) east of the volcano. In response to multiple signs of unrest, AVO elevated the Aviation Color Code to YELLOW and Volcano Alert Level to ADVISORY on December 6. Observations of degassing and energetic small explosions continued through December."
From Cameron and others, 2023: "The overall activity at Shishaldin Volcano declined throughout January 2018, and on February 7, 2018, this continued decline triggered AVO to lower the Aviation Color Code and Volcano Alert Level of the volcano to GREEN and NORMAL. No other notable unrest took place at the volcano for the remainder of 2018."