Ora Caldera (original) (raw)

The Ora Caldera is a Permian supervolcano in the Southern Alps of northern Italy. This 42 km (26 mi) wide and 40 km (25 mi) long caldera was formed by a supereruption 277–274 million years ago that produced more than 1,000 km3 (240 cu mi) of rhyodacitic-rhyolitic ignimbrite. The ignimbrite from this eruption forms the 10 to 1,350 m (33 to 4,429 ft) thick Ora Formation, which represents the youngest eruptive unit of the Athesian Volcanic Group.