Iliamna Volcano
Updated: Jun 9, 2025 00:55 GMT -
stratovolcano
Cook Inlet (SW Alaska), 60.03°N / -153.09°W 
Summit height: 3053 m / 10,016 ft
Current status: normal or dormant (1 out of 5)
Last update: 7 Jun 2023 (Smithsonian / USGS Weekly Volcanic Activity Report)
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.
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Iliamna volcano eruptions: 1953(?), 1952(?), 1933(?), 1876, 1867, 1843(?), 1793(?), 1778-79, 1768(?)
radiocarbon-dated: 1650 ?, 450 BC ?, 2050 BC ?, 5050 BC ?
Latest nearby earthquakes
| Date and Time | Mag / Depth | Distance / Location | |||
|---|---|---|---|---|---|
| Jun 8, 11:00 pm (Universal Time) | 1.5 115 km | 3 km (1.8 mi) to the NE | Kenai Peninsula Borough, 134 mi southwest of Anchorage, Anchorage Municipality, Alaska, United States | Info | |
| Saturday, June 7, 2025 GMT (2 quakes) | |||||
| Jun 7, 04:17 pm (Universal Time) | 2.5 132 km | 9.9 km (6.1 mi) to the NW | 59 km NE of Pedro Bay, Alaska | Info | |
| Jun 7, 02:58 am (Universal Time) | 1.5 106 km | 13 km (7.8 mi) to the NE | 66 km WNW of Happy Valley, Alaska | Info | |
| Friday, June 6, 2025 GMT (4 quakes) | |||||
| Jun 6, 03:05 pm (Universal Time) | 1.5 129 km | 17 km (10.6 mi) to the SW | 47 km ENE of Pedro Bay, Alaska | Info | |
| Jun 6, 01:50 pm (Universal Time) | 1.6 103 km | 29 km (18 mi) to the SE | 142 mi southwest of Anchorage, Anchorage Municipality, Alaska, United States | Info | |
| Jun 6, 12:54 pm (Universal Time) | 1.6 127 km | 17 km (10.5 mi) to the W | 48 km NE of Pedro Bay, Alaska | Info | |
| Jun 6, 01:02 am (Universal Time) | 1.6 80 km | 28 km (18 mi) to the E | 30 mi northwest of Anchor Point, Kenai Peninsula Borough, Alaska, United States | Info | |
| Saturday, May 31, 2025 GMT (3 quakes) | |||||
| May 31, 10:49 am (GMT -8) | 3.4 118 km | 10.2 km (6.4 mi) to the S | 56 mi west of Homer, Kenai Peninsula Borough, Alaska, United States | Info | |
| May 31, 03:10 am (GMT -8) | 2.4 85 km | 23 km (14 mi) to the E | 53 km WNW of Anchor Point, Alaska | Info | |
Background
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.
Significant volcanic eruptions: Iliamna volcano
In the past 10,000 years, Iliamna has had at least 7 confirmed volcanic eruptions, out of which 3 are documented by historical records, while the others can be inferred from geological evidence.
Additionally, there are 10 uncertain or discredited eruptions from Iliamna volcano.
Additionally, there are 10 uncertain or discredited eruptions from Iliamna volcano.
The table below lists all known eruptions (date in bold face) of Iliamna volcano in historic times and during the past 10,000 years. Updates on the most recent volcanic activity of Iliamna can be found on the news page of Iliamna volcano.
| Date | Note | VEI | Deaths | Damage | ||
|---|---|---|---|---|---|---|
Discredited Eruption | ||||||
Discredited Eruption | ||||||
?? | Uncertain Eruption | 2? | ||||
?? | Uncertain Eruption | ? | ||||
?? | Uncertain Eruption | ? | ||||
?? | Uncertain Eruption | ? | ||||
Historical obs./docs. | 3 | |||||
Historical obs./docs. | 2 | |||||
?? | Uncertain Eruption | ? | ||||
?? | Uncertain Eruption | ? | ||||
?? | Uncertain Eruption | ? | ||||
Historical obs./docs. | ? | |||||
?? | Uncertain Eruption | ? | ||||
| ? | ||||||
| ? | ||||||
| Upper NE flank | 4P | |||||
| 4P | ||||||
Remark:
Our list of volcanic eruptions closely follows the database of eruptions of the Smithsonian's Global Volcanism Project (GVP), the internationally most recognized data source for volcanic eruptions, but also includes significant eruptive episodes or related volcano events. "Volcanic eruptions" are usually to be understood as sequences of individual eruptive episodes that can follow each other, or even overlap (if several vents are involved), and can last many years, decades or even longer. For example, the current activity of Stromboli volcano is understood as a single eruption that has been ongoing since 1934.
Sources: NOAA National Centers for Environmental Information (NCEI), Global Significant Volcanic Eruptions Database. doi:10.7289/V5TD9V7K | Global Volcanism Project / Smithsonian Institution
Eruptions of Iliamna volcano
1996-97 earthquake swarms
During 1996-97, dike intrusions under the volcano caused several shallow earthquake swarms, but no eruption. ...more info
During 1996-97, dike intrusions under the volcano caused several shallow earthquake swarms, but no eruption. ...more 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.
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.
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.
Iliamna Volcano FAQ
+When was the last eruption of Iliamna volcano?
The last confirmed eruption of Iliamna occurred in 1876.
+How often does Iliamna volcano erupt?
Since 1778, Iliamna volcano has had at least 3 historically documented eruptions. This means that it erupts on average every 82 years.
Many eruptions of Iliamna have lasted more than one year. In total, the volcano has been in eruption during 4 out of 247 years until now. In other words, Iliamna has been active at least one in 61.8 years on average. Note that this value is likely an underestimate, because the known history of eruptions from Iliamna is likely incomplete, especially further back in time.
+When was the largest eruption of Iliamna volcano?
The largest eruption known from the younger geological history of Iliamna volcano occurred in 2050 BC. It ranks as a "vulcanian" eruption with a magnitude 3 on the VEI (Volcanic Explosivity Index) scale.
Latest satellite images
Iliamna Volcano Maps
Below is a selection of maps showing the location and surroundings of the volcano at various resolutions based on aerial-imagery / terrain maps. Feel free to use them for non-commercial purposes on your blog or website as long as you credit them with a link back to this page (click to copy it).
Satellite/aerial-type map of Iliamna volcano (world scale)
Terrain-type map of Iliamna volcano (world scale)
Satellite/aerial-type map of Iliamna volcano (region scale large)
Terrain-type map of Iliamna volcano (region scale large)
Satellite/aerial-type map of Iliamna volcano (region scale medium)
Terrain-type map of Iliamna volcano (region scale medium)
Satellite/aerial-type map of Iliamna volcano (region scale small)
Terrain-type map of Iliamna volcano (region scale small)
Satellite/aerial-type map of Iliamna volcano (local scale large)
Terrain-type map of Iliamna volcano (local scale large)
Satellite/aerial-type map of Iliamna volcano (local scale medium)
Terrain-type map of Iliamna volcano (local scale medium)
Satellite/aerial-type map of Iliamna volcano (local scale small)
Terrain-type map of Iliamna volcano (local scale small)
Satellite/aerial-type map of Iliamna volcano (scale of 10s of km)
Terrain-type map of Iliamna volcano (scale of 10s of km)
Satellite/aerial-type map of Iliamna volcano (scale of 20-40 km)
Terrain-type map of Iliamna volcano (scale of 20-40 km)
Satellite/aerial-type map of Iliamna volcano (scale of approx. 10-20 km)
Terrain-type map of Iliamna volcano (scale of approx. 10-20 km)
Satellite/aerial-type map of Iliamna volcano (scale of 5-10 km)
Satellite/aerial-type map of Iliamna volcano (scale of few kilometers)
