Eruption history
VEI – Volcanic Explosivity Index: 0 = lava outpouring, 4 = like Eyjafjallajökull 2010, 6 = like Pinatubo 1991, 7 = like Tambora 1815. The scale is logarithmic – each step is about 10 times more material.
| Start | End | VEI | Vent and dating |
|---|---|---|---|
| 12 July 2008 | 19 August 2008 | 4 | NE caldera floor · Observations: Reported |
| 11 February 1997 | 19 May 1997 | 3 | SW part of caldera (Cone A) · Observations: Reported |
| 18 November 1986 | 26 February 1988 | 2 | SW part of caldera (Cone A) · Observations: Reported |
| 8 July 1983 | 8 July 1983 | 2 | SW part of caldera (Cone A) · Observations: Reported |
| 24 March 1981 | 24 March 1981 | 3 | SW part of caldera (Cone A) · Observations: Reported |
| 15 October 1960 | 15 April 1961 | 3 | SW part of caldera (Cone A) · Observations: Reported |
| 14 August 1958 | 25 August 1958 | 3 | SW part of caldera (Cone A) · Observations: Reported |
| 4 June 1945 | 16 December 1945 | 2 | SW part of caldera (Cone A) · Observations: Reported |
| 16 June 1943 | — | 1 | SW part of caldera (Cone A) · Observations: Reported |
| 2 July 1938 | — | ? | SW part of caldera (Cone A) · Observations: Reported |
| 21 March 1931 | 13 May 1931 | 2 | Cone A? · Observations: Reported |
| 2 July 1899 | — | 3 | SW part of caldera (Cone A) · Observations: Reported |
| 2 July 1878 | — | 2 | Cone A? · Observations: Reported |
| 2 July 1824 | 2 July 1830 | ? | Cone B? · Observations: Reported |
| 1 March 1817 | 2 July 1820 | 3 | Cone E? or B? · Observations: Reported |
| 2 July 1805 | — | ? | Observations: Reported |
| 100 BCE ± 50 years | — | 6 | Okmok II caldera · Isotopic: 14C (uncalibrated) |
| 6,310 BCE ± 500 years | — | 4 | Isotopic: 14C (uncalibrated) |
Data: Global Volcanism Program, Smithsonian Institution (#311290)