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Iliamna Volcano

Updated: 29 mars. 2024 08:54 GMT -
stratovolcano 3053 m / 10,016 ft
Cook Inlet (SW Alaska), 60.03°N / -153.09°W
Condition actuelle: normal / en sommeil (1 sur 5)
Last update: 7 juin 2023 (Smithsonian / USGS Weekly Volcanic Activity Report)
The summit of Iliamna volcano with active fumaroles (photo: Tina Neal, Alaska Volcano Observatory / USGS)
The summit of Iliamna volcano with active fumaroles (photo: Tina Neal, Alaska Volcano Observatory / USGS)

Iliamna volcano is a large stratovolcano on the western side of the Cook Inlet, in Lake Clark National Park 220 km SW of Anchorage or 100 km NW of Homer.
There are several uncertain reports about activity in the past 250 years, but the only confirmed known historical eruptions were small to moderate explosive eruptions in 1876, 1867, and between 778 and 1879. A larger eruption with pyroclastic flows was dated by radiocarbon method and occurred between 300 and 140 years ago, but was not observed. Most of the sparse eruption reports from Iliamna are probably referring to strong activity of fumaroles located east and SE of the summit.

[smaller] [larger]
Style éruptif tipique: explosive
Eruptions du volcan Iliamna: 1953(?), 1952(?), 1933(?), 1876, 1867, 1843(?), 1793(?), 1778-79, 1768(?)
radiocarbon-dated: 1650 ?, 450 BC ?, 2050 BC ?, 5050 BC ?

Derniers séismes proches

HeureMag. / ProfondeurDistance / Lieu
19 mars 19:56 (Anchorage)
20 mars. 03:56 GMT
2.3

111 km
12 km au sud-ouest 50 km ENE of Pedro Bay, Alaska Info
mardi, 19 mars 2024 GMT (1 séisme)
18 mars 23:27 (Anchorage)
19 mars. 07:27 GMT
2.3

154 km
13 km au nord-ouest 58 km E of Port Alsworth, Alaska Info
dimanche, 17 mars 2024 GMT (1 séisme)
17 mars 02:08 (Anchorage)
17 mars. 10:08 GMT
3.1

95 km
21 km au sud-est États-Unis, 59 km à l'ouest de Anchor Point, Kenai Peninsula, Alaska Info
mardi, 26 mars 2024 GMT (1 séisme)
25 mars 23:15 (Anchorage)
26 mars. 07:15 GMT
2.2

124 km
19 km au sud-ouest Kenai Peninsula, États-Unis, 237 km au sud-ouest de Alaska City, Anchorage, Alaska Info
jeudi, 21 mars 2024 GMT (1 séisme)
21 mars 10:00 (Anchorage)
21 mars. 18:00 GMT
2.2

130 km
24 km au sud-ouest 41 km ENE of Pedro Bay, Alaska Info
lundi, 18 mars 2024 GMT (1 séisme)
18 mars 10:37 (Anchorage)
18 mars. 18:37 GMT
2.1

97 km
26 km au sud-est 50 km WNW of Anchor Point, Alaska Info

Introduction

Iliamna volcano has no distinct summit crater, but forms a flat top joined on the south by a 5 km long ridge with the prominent flank lava domes of North and South Twin Peaks. Another important flank vent is the Johnson Glacier dome on the NE flank.
Steep headwalls on the southern and eastern flanks expose an inaccessible cross-section of the volcano.
Several major glaciers radiate from its summit; the 4 largest together contain an estimated volume of 15 cubic km of ice.
Eruptions producing pyroclastic flows have been dated at as recent as about 300 and 140 years ago (into the historical period), and elevated seismicity accompanying dike emplacement beneath the volcano was recorded in 1996.

Eruptions du volcan Iliamna



1996-97 earthquake swarms
During 1996-97, dike intrusions under the volcano caused several shallow earthquake swarms, but no eruption. ...plus d'info

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.

Latest satellite images

Iliamna satellite image sat1Iliamna satellite image sat2
mer., 7 juin 2023, 14:00

Iliamna volcano (Alaska Peninsula) - Smithsonian / USGS Weekly Volcanic Activity Report for 31 May-6 June 2023 (Continuing Activity)

AVO reported that seismic activity at Iliamna began to increase at around 1200 on 5 June. Initially earthquakes occurred about every one minute, then became more closely spaced. The source of the activity was possibly from movement of magma or hydrothermal fluids beneath the volcano, though similar activity had been observed before large mass movements or avalanches; AVO could not rule out either. ... Read all
mar., 6 juin 2023, 06:02

Iliamna volcano (Cook Inlet, SW Alaska): ice-rock avalanche followed earthquakes

Vertical-component seismic waveforms and spectrograms from AVO station ILSW for the May 2016, June 2019, and June 2023 avalanches on Iliamna volcano (image: AVO)
An elevated seismic activity occurred beneath the volcano yesterday. ... Read all

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