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 |
|---|---|---|---|
| 13 July 1989 | 13 July 1989 | 1 | Teishi-kaikyu (4 km NE of Ito City) · Observations: Reported |
| c. 750 BCE | — | 3 | Iwano-yama, Iyuzan, and other vents · Correlation: Tephrochronology |
| 1,150 BCE ± 50 years | — | 4 | Kawagodaira · Isotopic: 14C (calibrated) |
| c. 2,050 BCE | — | ? | Yoichizaka · Correlation: Tephrochronology |
| 2,100 BCE ± 100 years | — | 4 | Omuro-yama · Isotopic: 14C (calibrated) |
| c. 8,050 BCE | — | 3 | Akakubo · Correlation: Tephrochronology |
Data: Global Volcanism Program, Smithsonian Institution (#283010)