USGS Photo Glossary:

Photograph by D.W. Peterson

Mauna Loa Volcano, Hawai`i. Snow-covered Moku`aweoweo Caldera atop Mauna Loa shield volcano (Mauna Kea in background). The caldera is 3 x 5 km across, 183 m deep, and is estimated to have collapsed between 600-750 years ago. Several pit craters along the upper southwest rift zone of Mauna Loa (lower right) also formed by collapse of the ground. For more information about the world's largest volcano, see Mauna Loa Volcano from the USGS Hawaiian Volcano Observatory.

Photograph by C. Neal on June 4, 1990

Kaguyak volcano, Alaska. This lake-filled caldera formed atop a former stratovolcano (note remnant of upper part of older cone at right center). The caldera formed about 1,100 years ago and is 2.5 km in diameter. The prominent peninsula and small island consists of lava domes erupted after the caldera formed.

Photograph by B. Yount on April 11, 1984

Ugashik volcano, Alaska. Aerial view, looking southwest, of Ugashik caldera. The caldera is 5 km in diameter and is partially filled by at least five lava domes erupted after the caldera formed.

Photograph by D. Wieprecht on August 20, 1995

Crater Lake, Oregon. Crater Lake partially fills an 8-10 km-wide caldera that formed when the top of the Cascade volcano known as Mount Mazama collapsed during an enormous explosive eruption about 7,700 years ago. The eruption expelled about 50 km³ of magma. This cataclysmic event was followed by a series of post-caldera eruptions until about 5,000 years ago. These smaller events erupted lava flows, a lava dome, and tephra from vents on the caldera floor. Such activity built Wizard Island (above) on the western caldera floor. A 1997 report describes the various types of volcano and earthquake hazards in the Crater Lake area, estimates the likelihood of future events, suggests ways to reduce risk, and includes a map of hazard zones.

Photo glossary of volcano terms

Calderas