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00:01: Most continuous seismic activity since 22:00, 12/17.
01:00: Seismic activity declines over last hour.
02:00: 1-2 minute "calms" between short periods of seismic activity characterized by last hour.
03:35: Strong burst of activity on recorders lasting about 20 minutes.
05:15: Increased seismic activity with microbursts recorded on all stations, declines to previous level by 05:35.
09:30+: AVO field crews report two major channels carved into the Drift glacier.
10:35: Pilot report of plume estimated at 20,000 feet and drifting to SE.
10:42: DROF crew reports ash plume rising to about twice the height of the continuous steam plume; time noted "some minutes" after start of event.
12:40: AVO report of plume consists of billowing steam clouds rising to about 20,000 ft. Ash separates from the plume at low altitudes. The eruption vent is located between 8,000 and 8,500 ft. A "curtain of steam" rises from the north flank down to about 4,500 ft. and individual steam plumes are visible farther down the valley to about 2,500 ft.; these plumes are probably related to hot water emanating from the vent and flowing down channels in the Drift River Glacier.
14:00+: DROF crews record ashfall at DROF.
14:32: Pilot report of "ash cloud" with top estimated at between 18,000 and 20,000 feet and moving E.
22:00: Basically no change in seismic activity through day.