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Types and Processes Gallery - Lava Dome

Lava Dome
Lava domes are formed when viscous magma slowly extrudes from a vent and piles up around it. Silicon promotes rigidity in magmas because it has a +4 charge and forms multiple bonds with other elements. Domes are consequently often produced by magmas of more silica-rich dacitic-to-rhyolitic compositions. Domes are steep-sided structures typically a few tens of meters to a few hundred meters high and can form at the summit of a volcano, on its flanks, or as independent volcanic centers. Domes can form during single eruptive episodes or by periodic lava extrusion, such as occurred during the 1980-1986 eruption of Mount St. Helens. Compound lava domes, such as currently forming at Santiaguito at the base of Santa María volcano in Guatemala, are common. Some volcanoes, such as Augustine in Alaska, consist entirely of a complex of overlapping summit lava domes surrounded by fragmental material produced during growth and collapse of the domes. Dome formation is often preceded or accompanied by explosive eruptions, and dome collapse can produce pyroclastic flows and debris avalanches.

Merapi
A lava dome that was produced during 1972-1985 lies within the summit crater of Merapi volcano in central Java. A small spine appears on the right in this 4 July 1986 photo, which was taken during a period of inactivity prior to destruction of the dome on 10 October 1986. Historical eruptions have been characterized by repeated growth and collapse of the summit lava domes, periodically producing pyroclastic flows that have impacted communities on the western and southern flanks.

Photo by Tom Casadevall, 1986 (U.S. Geological Survey).


Merapi
Incandescent rockfalls can be seen accompanying growth of a Merapi lava dome beneath clouds covering the summit in this 1993 nighttime view. Periodic collapse of Merapi's lava dome has produced pyroclastic flows down the western and southern flanks that have devastated populated areas and agricultural lands.

Photo by Ruska Hadian, 1993 (Volcanological Survey of Indonesia).


Unzendake
This closeup view on 20 May 1991 shows the first lava extrusion of the 1990-95 dome of Unzen volcano in Japan. The dome was extruded in the Jigokuato crater, which was formed by an explosion on the first day of the eruption, 17 November 1990. By 23 May the dome had reached a height of 44 m with a diameter of 110 m. It proceeded to grow over the east crater rim (upper right). Periodic collapse of the steep front of the dome produced pyroclastic flows that traveled progressively farther down the Mizunashi valley.

Photo courtesy Shimbara Earthquake and Volcano Observatory, 1991.


Unzendake
The 1990-95 eruption of Unzen volcano, in Kyushu, southern Japan, produced a lava dome at the summit. The rising sun colors the dome, seen here from the NE on 2 February 1995, near the end of the eruption. By this time the dome had grown to about 200 m above the pre-eruption surface. Periodic collapse of the growing lava dome had produced pyroclastic flows that devastated areas on the SE and NE flanks, resulting in the evacuation of thousands.

Photo by Tom Pierson, 1995 (U.S. Geological Survey).


Bezymianny
The Novy lava dome at Kamchatka's Bezymianny volcano began growing in 1956 within the large horseshoe-shaped crater. The 1.8 x 2.5 km crater formed during the catastrophic 1956 eruption flank collapse that resulted in a debris avalanche and lateral blast to the E. This 1980's view from the SW shows the dome within the crater, which subsequently grew to the height of the crater rim.

Photo by Yuri Doubik (Institute of Volcanology, Petropavlovsk).


Bogoslof
Lava dome remnants from three historical eruptions can be seen in this NW-looking aerial view of Bogoslof Island in the Aleutians. The pinnacle on the left is Castle Rock, also referred to as Old Bogoslof, a remnant of a 1796 lava dome. The circular, flat-topped area to its right is a remnant of a 1927 lava dome. The 1992 eruption produced the light-colored conical lava dome forming the tip of the island at top right. Regular eruptions and vigorous wave erosion frequently modify the island.

Photo by Chris Nye, 1994 (Alaska Division of Geological & Geophysical Surveys).


Bogoslof
An aerial view shows the 1992 lava dome of Bogoslof Island, the summit of a largely submarine located in the Bering Sea 50 km behind the main Aleutian arc. The 1992 lava dome grew to a height of 100 m in July at the northern tip of the island. In May 1994, when this photograph was taken, the island was about 1.5 x 0.6 km wide, and due to frequent eruptive activity and energetic wave action, has changed shape dramatically since first mapped in the late 1700's.

Photo by Tom Miller, 1994 (Alaska Volcano Observatory, U.S. Geological Survey).


Redoubt
This view from the north shows the final lava dome of the 1989-90 eruption of Alaska's Redoubt volcano approximately one year after the end of the eruption. The dome measures 350-400 m across and contains around 10 million cubic meters of material. In this photo, snow is accumulating on the cooling lava blocks while hydrothermal activity continues to produce intermittent steam plumes. Periodic lava dome growth during the eruption was punctuated by strong explosions that destroyed earlier lava domes.

Photo by Game McGimsey, 1991 (Alaska Volcano Observatory, U.S. Geological Survey).


St. Helens
Incandescence is visible in fractures in a growing lava dome in the crater of Mount St. Helens on 18 October 1980. Several earlier lava domes that formed after 18 May 1980 had been removed by explosive eruptions. This photo shows the beginning stages of the lava dome that grew incrementally until the end of the eruption in October 1986.

Photo by Terry Leighley, 1980 (U.S. Geological Survey).


St. Helens
Beginning in October 1980, activity during 17 eruptive episodes built this lava dome that grew to 876 m above the crater floor, shown here in April 1983. During a 12-month period beginning in 1983 the dome primarily grew by magma rising into the interior of the dome, called endogenous dome growth. Hundreds of small gas-and-steam explosions occurred at the dome.

Photo by Bob Symonds, 1983 (U.S. Geological Survey).


Lassen Volcanic Center
Chaos Crags in the foreground and Lassen Peak in the background are large lava dome complexes in the southern Cascade Range. Chaos Crags consists of a group of six overlapping rhyodacite lava domes that erupted around 1,100 years ago. Lassen last erupted during 1914-17.

Photo by Dan Dzurisin, 1982 (U.S. Geological Survey).


Ceboruco
A small lava dome was extruded in the main vent of the 1870-75 eruption of Ceboruco volcano in western México. Fumaroles (not visible in this photo) with temperatures measured at about 100°C were located around the base of the dome when the photo was taken in 1997.

Photo by Lee Siebert, 1997 (Smithsonian Institution).


El Chichon
A forested lava dome, seen here from the east in 1974, filled the crater of México's El Chichón volcano and formed its highest point prior to a major eruption in 1982. The low ridge cutting across the middle of the photo is the rim of the pre-1982 crater. Powerful explosive eruptions in March and April 1982 removed the lava dome and produced a 1-km-wide crater.

Photo by Paul Damon, 1974 (University of Arizona).


Santa Maria
Incandescence is visible at the top of the growing Santiaguito lava dome in Guatemala. Rockfalls of hot material produce a visible trail down its northern flank. The dome began growing in 1922 in a large crater formed on the SW flank of Santa María volcano during a powerful explosive eruption in 1902. Dome growth has been continuous since 1922 and has produced a composite dome over 3 km long. This photo of El Brujo, the westernmost vent, was taken on 12 November 1967.

Photo by Charles Pineo, 1967 (Dartmouth College, courtesy of Dick Stoiber).


Santa Maria
A small blocky lava dome within the Caliente vent on the Santiaguito lava dome of Guatemala's Santa María volcano on 18 July 1969. This was near the beginning of a period of renewed activity at this vent. Growth of the composite Santiaguito lava dome has been ongoing since 1922.

Copyrighted photo by Dick Stoiber, 1969 (Dartmouth College).


Pululahua
Cerro Sincholagua (left) and Loma la Marca (right) are the southernmost of a group of lava domes at Pululahua volcano. Seen here from the south, they are part of a chain of lava domes that were constructed on a roughly N-S line east of the Pululahua caldera.

Photo by Lee Siebert, 1978 (Smithsonian Institution).


Pululahua
Pululahua is a relatively low-profile, forested volcano immediately north of the equator, 27 km N of Quito. Loma Pondona (left) and the lower Rumiloma (right center) are two of a group of lava domes that partially fill a 3-km-wide caldera. They are seen here from the SE caldera rim. The caldera was formed during the latest dated eruption about 2,400 years ago. Large explosive eruptions were accompanied by pyroclastic flows during the late Pleistocene and Holocene.

Photo by Lee Siebert, 1978 (Smithsonian Institution).


Soufriere Hills
Scientists from the Montserrat Volcano Observatory make monitoring measurements in February 1997 as small rockfalls descend the flanks of the lava dome. Castle Peak lava dome, constructed during the previous eruption of Soufrière Hills during the 17th century, had collapsed three days before this photograph was taken from the Tar River Estate house, 2 km NE of the dome. Periodic collapse of the growing lava dome produced pyroclastic flows that in some cases reached the sea.

Photo by Mark Davies, 1997 (Montserrat Volcano Observatory).


Soufriere St. Vincent
A lava dome 130 m high and more than 840 m wide filled much of the crater floor of Soufrière St. Vincent volcano during the 1979 eruption. Dome growth began in May, after a series of powerful explosive eruptions 13-15 April, and continued until October. Steam continued to rise from the dome in this 1983 photo from the SW crater rim.

Photo by Richard Fiske, 1983 (Smithsonian Institution).