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Types and Processes Gallery - Calderas

Calderas
Calderas are large volcanic depressions formed by collapse of the summit or flanks of a volcano into underlying chambers evacuated by very large explosive eruptions or the effusion of large volumes of lava flows. Earth's calderas range from a kilometer to as much as about 100 kilometers in width; many contain scenic caldera lakes. Calderas may be simple structures formed during an eruption that truncates either the summit of a single stratovolcano or a complex of multiple overlapping volcanoes, such as at Crater Lake in Oregon. Other calderas are compound structures formed incrementally as a result of multiple eruption-related collapses, such as the massive 30 x 100 km wide Toba caldera in Sumatra, which was formed during four powerful explosive eruptions during the Pleistocene. Calderas are most often defined as depressions produced as a result of large-scale eruptions, but the word has also been used as a morphological term that encompasses volcanic depressions formed by erosion or large volcanic landslides. Calderas may be ephemeral features that are partially or totally obscured by post-caldera eruptions.

Toba
The 35 x 100 km wide Toba caldera, partially filled by Sumatra's Lake Toba, is Earth's largest Quaternary caldera. This view looks W toward the northern end of Samosir Island, which is part of a block that was 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.

Photo by Tom Casadevall, 1987 (U.S. Geological Survey)


Toba
Toba is Earth's largest Quaternary caldera and is partially filled by Lake Toba, seen here in a NASA Landsat satellite image (N is to the top). The 35 x 100 km caldera 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 an uplifted resurgent dome.

NASA Landsat7 image (worldwind.arc.nasa.gov)


Banda Api
The arcuate islands of Banda Neira and Lonthor, seen here looking E 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 and the nested inner caldera is 3 km wide. Neira, the largest town in the Banda Islands, occupies the southern tip of Banda Neira Island.

Photo courtesy Tom Casadevall, 1988 (U.S. Geological Survey).


Taal
A 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 the much larger 15 x 20 km Taal caldera, of which the western wall is seen across Lake Taal in the distance. The small island in the center of the photo is a remnant of historical eruptions on Volcano Island and is an island in a lake, on an island in a lake, on an island.

Photo by Chris Newhall, 1989 (U.S. Geological Survey).


Pinatubo
The major explosive eruption on 15 June 1991 created a 2.5-km-wide caldera at the summit of Pinatubo. The elevation of the caldera floor is more than 900 m below that of the pre-eruption summit. Plumes rise from fumaroles on the caldera floor in this 4 October 1991 photo taken from the N. The outer flanks of the caldera are stripped of vegetation and covered with ash and pyroclastic surge deposits.

Photo by Chris Newhall, 1991 (U.S. Geological Survey).


Mashu
Mashu is a 6-km-wide caldera on the northernmost Japanese island of Hokkaido, seen here from the SW rim with the Kamuishi Island lava dome in the center of the lake. It truncates a stratovolcano on the ESE rim of the larger Kutcharo caldera. The latest eruption of Mashu took place about 1,000 years from Kamuinupuri, the lower flanks of which appear to the far-right.

Photo by Lee Siebert, 1977 (Smithsonian Institution).


Akademia Nauk
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 to the upper left is the southern rim of Odnoboky caldera, and the northern rim is truncated by the Akademia Nauk. Karymsky Lake fills the 3 x 5 km Akademia Nauk caldera that most recently erupted in 1996.

Photo by Dan Miller, 1990 (U.S. Geological Survey).


Uzon
The Uzon and Geyzernaya calderas, containing Kamchatka's largest geothermal area, form a 7 x 18 km depression that formed 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 contains numerous lakes, streams, and thermal areas. Sharp-peaked Kronotsky volcano and flat-topped Krasheninnikov volcano appear in the distance beyond the N caldera rim.

Photo by Dan Miller, 1990 (U.S. Geological Survey).


Aniakchak
Aniakchak is a 10-km-wide summit caldera containing numerous cones, lava domes, and lava flows on the caldera floor. The largest intra-caldera cone is Vent Mountain that reaches 430 m in height and has a diameter at the base of 2.5 km. At least 20 Holocene eruptions may have occurred before the Aniakchak II caldera-forming eruption.

Photo by M. Woodbridge Williams (National Park Service).


Crater Lake
The 8 x 10 km wide Crater Lake caldera was formed about 7,700 years ago when Mount Mazama, a complex of overlapping stratovolcanoes, collapsed following a major explosive eruption. The eruption produced widespread ashfall and pyroclastic flows that traveled as far as 70 km. The caldera, seen here from the S rim, is 1,200 m deep and filled to half its depth by Crater Lake.

Photo by Dave Wieprecht, 1995 (U.S. Geological Survey).


Masaya
A broad expanse of lava flows extends across the floor of Nicaragua's Masaya caldera, with the wall forming the arcuate rim in the background. The lava flows originated from the post-caldera cones of Masaya and Nindirí. Lake Masaya is located 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.

Photo by Jaime Incer.


Apoyo
The 7-km-wide, lake-filled Apoyo caldera is seen here from the W with Lake Nicaragua in the distance beyond its low eastern caldera rim. The surface of Laguna de Apoyo is 78 m above sea level. The steep caldera walls rise about 100 m along the eastern rim and up to 500 m along the western rim (foreground). The caldera was formed during two major dacitic explosive eruptions radiocarbon dated at about 23,000 years BP.

Photo by Jaime Incer.


Askja
Askja is a central volcano made up of the Dyngjufjöll massif and at least three calderas, the largest of which is 8 km wide. This view from the SE looks across Öskjuvatn lake within the youngest caldera that formed in 1875 during Askja's largest historical eruption. It 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 Sveinagjá graben, is also related to the Askja volcanic system.

Photo by Michael Ryan, 1984 (U.S. Geological Survey).


Deception Island
Deception Island in Antarctica contains a 7-km-wide caldera flooded by the sea. A narrow passageway named Neptune’s Bellows cuts through the caldera wall to the left. Numerous vents located along the caldera ring fractures around the low, 14-km-wide island have been active during historical time. Maars produced by magma-water interaction occur across the shores of the 190-m-deep Port Foster.

Photo by Juan Bastias (published in González-Ferrán, 1995).