[microgood]

one of the largest calderas in the world and certainly the largest in the U.S

Nice photos. Is this caldera larger than the Yellowstone caldera? I thought Yellowstone's was the second largest in the world, next to one in India.

[cogitator]

Is this caldera larger than the Yellowstone caldera?

There are a variety of estimates available, but the best estimate I could find puts the diameter of Jemez, better known as Valles, Caldera at about 20-24 km. Yellowstone has three overlapping calderas, so while the whole area may be larger, the individual calderas aren't quite as large as Valles. (So I understand -- obviously this is an area subject to geological interpretation.)