Maat Mons has a large summit caldera, 28x31 km in size.

Half of all eruptions occur at or near Kīlauea's summit caldera.

They discovered a fissure vent near the summit caldera a bit to the west of Guðnasteinn.

There is a small string of faults on and near the main summit caldera, arranged parallel to the northern coast.

The magma, called lava as it pours out of the summit caldera, does indeed arise from the underworld.

A few low mounds with summit calderas were found-almost certainly lunar volcanos.

A 3 km-wide summit caldera tops the volcano and a sample from there yielded a potassium-argon date of 500,000 years ago.

The summit caldera is quite large, being approximately 3 x 4 km (1.9 x 2.5 miles) in size at the rim (2007).

The summit caldera is estimated to have collapsed between 200,000 and 50,000 years ago.

A former summit caldera may have been filled and buried by later summit eruption deposits.