Iliamna Volcano Eruptions
stratovolcano 3053 m / 10,016 ft
Cook Inlet (SW Alaska), 60.03°N / -153.09°W
Eruption list: 1953(?), 1952(?), 1933(?), 1876, 1867, 1843(?), 1793(?), 1778-79, 1768(?)
radiocarbon-dated: 1650 ?, 450 BC ?, 2050 BC ?, 5050 BC ?
Eruptions of Iliamna volcano
1996-97 earthquake swarms
During 1996-97, dike intrusions under the volcano caused several shallow earthquake swarms, but no eruption.
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A small shallow earthquake swarm occurred beneath Iliamna during mid-May 1996. Seismic activity increased again on 1 August and during September and the first half of October, 6 to 27 volcanic earthquakes were recorded each day. The activity continued through November, December and Januaray at lower, but still elevated levels (3-16 quaks per day), and slowly declined until by 28 March, seismicity was again at background levels..
The swarm was located 5 km S of the summit at a depth of less than 10 km, where magma is thought to have intruded, but never reached the surface to produce an eruption.
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Soource: Smithsonian / GVP Iliamna volcano monthly reports
1987 steam plume
On the morning of 19 March 1987 at 8am, several pilots observed an unusually large steam plume rising about 1000-1100 m above the summit of Iliamna. The plume originated from an area on the upper S flank vent, but did not contain visible ash.
The event is not counted as an eruption, but a period of exceptionally strong degassing from active fumaroles.
1978 steam eruption
A brief steam eruption occurred on 7 November 1978 between 10 and 13 h local time, producing puffs of steam, ejected every 1-5 minutes, that rose an estimated 3 km above the summit. No ash was visible in the steam puffs. No unusual seismic activity was recorded.