Aoga-shima volcano (青ヶ島, Aogashima) is a stratovolcano forming a beautiful small 2.5 x 3.5 km island with steep cliffs in the Izu island chain, 300 km south of Tokyo.
The dominantly basaltic Aoga-shima volcano contains a complex caldera (Ikenosawa Crater) with a diameter of 1.7 x 1.5 km. 2 cones were built inside the caldera during the volcano's last eruptions in 1781-85.
Activity of Aogashima volcano includes pyroclastic flows and lava flows from both summit and flank vents.
1781-85, 1670-80, 1652, 600 BC ± 200 years, 1100 BC ± 300 years, 1200 BC ± 50 years, 1800 BC ± 100 years
Style éruptif tipique
The oldest part of Aoga-shima volcano was the Kurosaki stratovolcano in the NW part of the island. The present-day stratovolcano grew later in the SE part of the island. A 1-1.5 km wide crater or caldera formed on the SE flank of the main cone.
About 3000 years ago a powerful explosive eruption produced pyroclastic surges that swept over the entire island, and during the activity in the following 600 years, most of the crater on the SE side was filled by lava flows and scoria deposits. Renewed collapse and possibly a debris avalanche re-formed the caldera and created the present-day Ikenosawa Crater, which also was the site of the historic activity.
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