Description: From Reeder (1989): "Steam-blast eruptive activity with and without ash occurred intermittently during 19 March 1986 up into 1987." Details of the 1986 eruption are in Reeder, 1989; details of the 1987 eruption are in Reeder, 1990.
From Reeder (1989): "At about 1325LT 19 march 1986, James Dickson, a resident of Unlaska, observed, while on a MarkAir Inc. flight from Dutch Harbor to Anchorage, yellow to brown wisp rise about 90 m above the summit crater of Shishaldin Volcano. Previous emissions strung out as a nearly transparent brown horizon toward the SW, which could be seen for over 50 km.
"Captain Jerry Chisum of MarkAir Inc., who flies the Dutch Harbor to Anchorage route often, observed another ash horizon from the volcano on 28 March. Based on Jerry's observations, Shishaldin normally emits intermittenly only minor amounts of steam from its summit crater.
"Several pilots observed anomalous steam and ash emission activity from the summit crater of Shishaldin Volcano on the 5 through 8 May 1986.
"At 1400LT 5 May, pilot Harold Wilson of Peninsula Airways Inc. observed continuous and very strong steam and ash emission from the summit crater that was rising 500 m above the volcano and trailing as far as one could see to the WNW over the Bering Sea. Harold observed some hot rock with debris avalanching from the crater rim.
"Captain Jerry Chisum observed at 1320LT 6 May an impressive steam plume with some ash that was continuously rising at a 45 degree angle to the 3,400 m altitude, and it had drifted then horizontally for 25 km. Captain Lee Goch of Reeve Aleutian Airways Inc. at 1350LT observed a steam plume with traces of ash. The slightly gray plume was drifting to the NE for at least 40 km at a 3,600 m altitude.
"Pilot Thomas Madsen, President of Aleutian Air Ltd. at Dutch Harbor, observed the plume at 1300LT 7 May. The plume trailed at about 3,600 m altitude to the S for at least 130 km. The plume had a definite gray tone with some streaks of dark ash. Captain Jerry Chisum also observed the impressive plume at 1320LT, at which time large puffs were occurring from the crater about every 20 minutes.
"Less intense activity was reported by both Tom and Lee on the 8 May. On the same day, Tom still detected a grayish plume that drifted for a considerable distance to the E."
From the 10th of May until the end of June, 1986, only steam plumes were observed at Shishaldin. Minor amounts of ash were observed on June 19th, and "smoke" throughout July.
Reeder (1989) continues: "On the 20 August 1986, Jason Currier, a resident of Unalaska, observed at 'close range' traces of ash along with voluminous amounts of steam being emitted from the volcano at 1345LT, while he was on a MarkAir Inc. flight from Dutch Harbor to Anchorage." Another steam plume was observed on 21 August.
Reeder (1989), continued: "On the 2 October 1986, Captain Jerry Chisum observed anomalous steam-blast activity with minor amounts of ash. Stephanie Madsen of Aleutian Air Ltd. of Dutch Harbor was on Jerry's flight to Dutch Harbor, and she observed at about 1145LT the Shishaldin steam plume with minor amounts of 'smoke' trailed to the SW for at least 15 km.
"On the 3 October 1986, Captain Harold Blake of Reeve Aleutian Airways Inc. observed at 1330LT anomalous steam puffs with minor amounts of ash from the Shishaldin summit crater." The steam plume drifted about 400 m above the summit crater, and puffs lasted about 3 minutes each, and were 3 minutes apart. Steam-blasts were observed on 4 October, and minor amounts of ash were visible on the flanks. Steam plumes were also observed on 8, 10, and 27 October. On 17 November, a steam plume with an ash haze was observed. Steam plumes were observed periodically throughout the end of the year.
Activity continued into 1987. Steam plumes were common at Shishaldin from January 1987 until March, 1987. Ash was observed on 15 February, and possibly on 26 February. Reeder (1990): "Marsha Brown observed from Cold Bay at 1600LT 15 February a large dark (apparent ash rich) plume that rose at least 600 m above the volcano and that then was drifting an unknown distance ENE toward Cold Bay. The plume did not exist two hours earlier. The plume was dark gray while other lower altitude nearby clouds were white to very light gray. She watched the plume until darkness at 1830LT.
"At 0925LT 26 February, Theresa Dubber at Cold Bay observed a 300 m high steam plume above the volcano that was drifting to the SW. Pilot Tom Madsen observed this plume at close range and thought he could recognize some traces of ash in the plume."