Seismic activity is monitored closely by New Zealand’s GeoNet. Aira Caldera (Japan) Size: 20 kilometers in diameter Potential Damage and Power: The Aira Caldera erupted 22,000 years ago ...

The pyroclastic flow and volcanic ash spewed out by the Aira caldera in southern Kagoshima Prefecture in Kyushu was 1.5 times larger than previous research estimates and reached a depth of about ...