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 |
|---|---|---|---|
| 690 ± 100 years | — | 4 | S caldera wall · Isotopic: 14C (calibrated) |
| 490 ± 100 years | — | 4 | South caldera wall · Isotopic: 14C (calibrated) |
| c. 1,450 BCE | — | ? | South of East Lake · Chem/Bio: Hydration Rind |
| c. 4,450 BCE | — | ? | Center, N & S caldera, upper SE flank · Chem/Bio: Hydration Rind |
| 4,690 BCE ± 150 years | — | 0 | NW rift zone · Isotopic: 14C (calibrated) |
| 4,770 BCE ± 75 years | — | ? | NW rift zone (Sugarpine Butte) · Isotopic: 14C (calibrated) |
| 4,860 BCE ± 150 years | — | 0 | NW rift zone · Isotopic: 14C (calibrated) |
| 4,960 BCE ± 100 years | — | ? | East Lake fissure, south flank · Isotopic: 14C (calibrated) |
| 5,070 BCE ± 150 years | — | 3 | Lower NW rift zone (Lava Butte) · Isotopic: 14C (calibrated) |
| 5,260 BCE ± 150 years | — | 0 | NW rift zone (Lava Cast Forest) · Isotopic: 14C (calibrated) |
| 9,210 BCE ± 1,200 years | — | ? | South and east caldera rim · Isotopic: 14C (calibrated) |
Data: Global Volcanism Program, Smithsonian Institution (#322110)