Akademia Nauk caldera in central Kamchatka, seen here from the slopes of Karymsky volcano looking SW, is one of two overlapping calderas formed during the late Pleistocene within the 15-km-wide Polovinka caldera. The snow-capped ridge at the upper left is the southern rim of Odnoboky caldera, whose northern rim is truncated by the Akademia Nauk caldera. Karymsky Lake fills the 3 x 5 km Akademia Nauk caldera, which had its first historical eruption in 1996.
Calderas are very large depressions that form by collapse. Many, like this 10-km-wide caldera that truncates Alaska's Aniakchak volcano, are created by very powerful explosive eruptions that empty a magma chamber beneath a volcano, causing it to collapse inward. Other calderas, such as those on Hawaiian volcanoes, are produced by collapse following major lava extrusion. Calderas often form incrementally, during widely spaced eruptions. Later activity can cover their floors with a wide variety of volcanic landforms.
Askja is a large central volcano that forms the Dyngjufjšll massif. It is truncated by three calderas, the largest of which is 8 km wide. This view from the SE looks across …skjuvatn lake, which fills the youngest caldera. It formed in 1875 during Askja's largest historical eruption and truncates a larger caldera, whose wall is seen in the distance above the lava-covered caldera floor. The 100-km-long Askja fissure swarm, which includes the Sveinagj‡ graben, is also related to the Askja volcanic system.
The arcuate islands of Neira and Lonthor, seen here looking east from the summit of Indonesia's Banda Api volcano, are remnants of two largely submarine calderas that preceded the construction of the Banda Api stratovolcano. The outer caldera has a diameter of 7 km, the nested inner caldera is 3 km wide. Neira, the largest town in the Banda Islands, occupies the southern tip of Neira Island.
The spectacular 8 x 10 km wide Crater Lake caldera was formed about 6850 years ago when Mount Mazama, a complex of overlapping shield volcanoes and stratovolcanoes, collapsed following a major explosive eruption. The eruption blanketed a huge area with ash falls and produced pyroclastic flows that swept all sides of the volcano. The caldera, seen here from its southern rim, is 1200 m deep and filled to half its depth by the intensely blue waters of Crater Lake.
Lake Masaya lies within the 6 x 11 km Masaya caldera, whose rim appears on the far side of the lake with Lake Nicaragua in the background. The construction of more than a dozen vents within the caldera has restricted Lake Masaya to an elongated, 2 x 6 km area at the far eastern end of the caldera. The eastern caldera rim rises 200 above the caldera floor, which is only 50 m above sea level.
A broad expanse of youthful lava flows extends across the floor of Nicaragua's Masaya caldera, whose wall forms the arcuate rim in the background. The lava flows originated from the post-caldera cones of Masaya and Nindirí and constrain Lake Masaya against the eastern caldera wall. Recent lava flows have flooded much of the caldera and have overflowed its rim in one location on the NE side. This view from the NW shows Mombacho volcano in the distance.
Mashu is a 6-km-wide caldera on the northernmost Japanese island of Hokkaido. It truncates a stratovolcano constructed on the ESE rim of the larger Kutcharo caldera. Mashu caldera is seen here from its SW rim with the small island of Kamuishi, a mostly submerged lava dome, in the center of the lake. The steep-walled caldera is one of the scenic highlights of Hokkaido. The latest eruption of Mashu took place about 1000 years from Kamuinupuri, whose lower flanks appear at the extreme right.
The climactic eruptions on June 15, 1991, created a 2.5-km-wide caldera at the summit of Pinatubo volcano. The elevation of the caldera floor is more than 900 m below that of the pre-eruption summit of Pinatubo. Steam rises from fumaroles on the caldera floor in this October 4, 1991, view from the north. The outer flanks of the caldera are stripped of vegetation and covered with deposits of airfall ash and pyroclastic surges.
A small, 3-km-wide caldera is located at the center of Volcano Island, in the Philippines' southern Luzon Island. The 5-km-wide Volcano Island lies within a much larger, 15 x 20 km Taal caldera, whose low, western wall is seen across Lake Taal in the distance. The small island in the center of the photo, a remnant of historical eruptions on Volcano Island, is a geographical oddity--an island in a lake on an island in a lake on an island.
Toba, the Earth's largest Quaternary caldera, is seen here in a false-color satellite image. The 35 x 100 km caldera, partially filled by Lake Toba, was formed during four major ignimbrite-forming eruptions in the Pleistocene, the latest of which occurred about 74,000 years ago. The large island of Samosir is a resurgent uplifted block. The solfatarically active Pusukbukit volcano was later constructed near the south-central caldera rim, and Tandukbenua volcano on the NW rim may be only a few hundred years old. Landsat image, 1987 (National Aeronautical and Space Administration/EOSAT).
The 35 x 100 km wide Toba caldera, partially filled by waters of Sumatra's Lake Toba, is Earth's largest Quaternary caldera. This view looks west toward the northern end of Samosir Island, which is part of a massive inclined block uplifted after eruption of the Young Toba Tuff (YTT) about 74,000 years ago. The island, once entirely covered by Lake Toba, is formed of caldera-fill deposits of YTT capped by lake sediments.
The Uzon and Geyzernaya calderas, containing Kamchatka's largest geothermal area, form a 7 x 18 km depression that originated during the mid-Pleistocene. Post-caldera activity was largely Pleistocene in age, although the Lake Dal'ny maar formed during the early Holocene. This view looks from the SW across the flat caldera floor, which is dotted with numerous lakes, streams, and thermal areas. Sharp-peaked Kronotsky volcano and flat-topped Krasheninnikov volcano appear in the distance beyond the north caldera rim.