|Start:||March 27, 2016 ||Observed|
|Lahar, debris-flow, or mudflow: ||
|Tephra plume: ||
|ColHeight: ||10600 m ||
|Duration: ||About 1 week ||
Pavlof Volcano began erupting abruptly on the afternoon of Sunday, March 27, 2016, sending an ash cloud to 20,000 ft ASL as reported by a pilot. As of 4:18 pm AKDT (00:18 UTC), ash was reportedly moving northward from the volcano. Seismicity began to increase from background levels at about 3:53 pm (23:53 UTC) with quick onset of continuous tremor. AVO raised the Aviation Color Code to RED and the Volcano Alert Level to WARNING. Ash emission continued until midday on March 28, with maximum heights of about 35,000 feet. The ash cloud from Pavlof extended more than 400 miles to the northeast of Pavlof, over interior Alaska. Lava fountaining and lightning were observed from Cold Bay. Minor ashfall occurred at Nelson Lagoon on the evening of March 27 and morning of March 28. Trace ashfall was reported at Dillingham, Port Heiden, and Togiak on March 28.
On the afternoon of March 28, seismicity began to decline, and evening ash emissions were observed to 20,000 ft asl. Citing the decline in ash emission, seismicity, and infrasound, AVO lowered the Aviation Color Code / Volcanic Alert Level to ORANGE/WATCH on Monday, March 28 at 6.01 pm AKDT.
On March 29, intermittent ash emissions below 15,000 ft were observed, and seismicity remained somewhat elevated. The drifting remnant ash plume from March 27 and 28 was still present in satellite imagery, extending over the Bering Sea and interior Alaska. Intermittent, low-level ash emissions continued on March 30. A pilot reported a possible low-level ash to 8,000 ft on March 31. For the next several days, cloudy conditions prevented direct observation of the volcano, although weakly elevated surface temperatures were observed in some satellite images, and seismicity remained elevated compared to background, but continued to decline.
On Wednesday April 6, AVO lowered the Aviation Color Code / Volcano Alert Level to YELLOW/ADVISORY, and stated tha the recent period of eruptive activity at Pavlof had ended. On April 22, AVO lowered Pavlof again to GREEN/NORMAL.
On Friday, May 13, 2016, seismic activity at Pavlof Volcano increased to levels typically associated with low-leve eruptive activity. AVO raised the Aviation Color Code / Level of Concern from GREEN/NORMAL to ORANGE/WATCH. During the day of May 14, seismicity remained elevated but clear webcam and satellite images showed no sign of eruption. Minor ash emissions at Pavlof were noted by local observers and in web camera views from about 19:27-21:07 AKDT (3:27-5:07 UTC). The diffuse ash plume reached heights of 15,000 - 18,000 feet asl, did not travel far, and remained in the vicinity of the volcano. Minor ash emission resumed at about 8:50 AKDT (16:50 UTC) on May 15, and elevated surface temperatures were also seen in satellite data. These thermal signals at Pavlof are typically associated with lava effusion and it is possible that low-level fountaining may have been temporarily occurring on the morning of May 15, 2016. Seismicity at Pavlof remained elevated - additional periods of small explosions and minor ash emission were observed on May 17, beginning around 4:45 AKDT (12:45 UTC). Ash emissions during this time were also reported by people in Cold Bay and Sand Point.
On May 20, 2016, citing declining seismic signals, satellite thermal signals, and lack of further ash emission, AVO lowered the Aviation Color Code and Volcano Alert Level to YELLOW/ADVISORY. Weak seismic tremor and small explosions were observed on May 21, but no ash emissions or evidence of elevated surface temperatures was detected in satellite or web camera data, indicating that activity was minor.
By June 17, seismicity had returned to its normal background state, and AVO lowered the Aviation Color Code and Volcano Alert Level at Pavlof to GREEN/NORMAL.
On July 1, noting an increase in seismicity over the past 24 hours, and steam plumes visible in the FAA Cold Bay webcam, AVO raised the Aviation Color Code and Volcano Alert Level to YELLOW/ADVISORY.