Logo link to homepage

Types and Processes Gallery - Stratovolcanoes

Stratovolcanoes
Stratovolcanoes (also known as composite volcanoes) are what most people associate with the word volcano. These towering peaks rise hundreds to several thousand meters above their surroundings, often visually dominating the landscape around them. As their name implies, they are formed of stratified layers of both viscous lava flows and fragmental material. Classic symmetrical stratovolcanoes such as Shishaldin in the Aleutian Islands and Mayon in the Philippines are the exception rather than the rule. Most stratovolcanoes are complex structures formed by multiple eruptions from summit and flank vents. Compound stratovolcanoes may form when the focus of eruptions shifts, forming multiple overlapping edifices. Some stratovolcanoes may form in a few thousand years, but may remain active for tens to hundreds of thousands of years. During their lifespans, dormant intervals may also last tens of thousands of years. Perhaps the most common rock type of stratovolcanoes is andesite (named after the Andes Mountains), but stratovolcanoes form in a wide variety of tectonic settings and erupt a wide range of rocks. Their steep-sided profiles are often exaggerated even further by artists for dramatic effect. Slopes of stratovolcanoes rarely exceed the angle of repose for fragmental material at about 30-35 degrees, and eruptions from multiple vents often produce complex volcanoes with greatly variable morphology.

Tongariro
Snow-capped Ngauruhoe, seen here from the NE, rises 800 m above its surroundings and is the highest peak of the Tongariro massif. This large massif is located immediately NE of Ruapehu volcano, and is comprised of more than a dozen cones and craters. Frequent explosive eruptions have been recorded from Ngauruhoe since 1839.

Photo by Don Swanson, 1984 (U.S. Geological Survey).


Wurlali
Wurlali volcano (also referred to as Damar), seen here from Cape Wilhelmus on the north, is part of Indonesia’s Banda Island chain. The stratovolcano was formed in the northern part of a 5-km-wide caldera. During historical time only a single explosive eruption occurred in 1892 from the summit crater.

Photo by K. Sumaryano, 1994 (Volcanological Survey of Indonesia).


Mayon
Mayon in the Philippines is one of Earth's best examples of a classic, conical stratovolcano. Its symmetrical morphology is the exception rather than the rule and is the result of eruptions that are restricted to a single central conduit at the summit. Eruptions are frequent enough to overcome erosion processes that quickly modify the slopes of most volcanoes.

Photo by Chris Newhall, 1993 (U.S. Geological Survey).


Hakusan
Eruptions at Hakusan occur at multiple vents along a roughly N-S line; the volcano is viewed here from the W. Holocene eruptions have consisted of phreatic or phreatomagmatic explosions at several summit craters. Historical eruptions were recorded over almost a thousand-year period until the 17th century.

Photo by Ishikawa Prefecture, 1983 (courtesy Toshio Higashino, Haku-san Nature Conservation Center).


Iwatesan
Iwatesan on Japan's northern island of Honshu, seen from the SW. The extensively-dissected Onigajo volcano forms the older, western part of Iwate and is truncated by the 1.8 x 3 km Nishi-Iwate caldera. The smoother slopes at the right are formed by ejecta from the younger Yakushidake cone, which was constructed on the eastern rim of the caldera.

Photo by Hidenori Togari, 1994 (Hokkaido University).


Kronotsky
Kronotsky stratovolcano Is located between the Pacific Ocean and Lake Kronotsky, Kamchatka's largest lake. The flanks are dissected by radial valleys up to 200 m deep. Weak phreatic eruptions took place during the 20th century. Kronotsky is seen here from the SW with the caldera rim of neighboring Krasheninnikov volcano in the foreground.

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


Klyuchevskoy
Klyuchevskoy volcano has had more than 100 flank eruptions during the past 3,000 years. The conical stratovolcano is one of the youngest and largest of Kamchatka's volcanoes, having produced 300 km3 of material since the early Holocene.

Photo by Vera Ponomareva, 1976 (Institute of Volcanic Geology and Geochemistry, Petropavlovsk).


Vsevidof
The effects of erosion are visible in this view from the SW of two prominent stratovolcanoes on SW Umnak Island in the Aleutians. Mount Vsevidof (left) is a near-symmetrical volcano where frequent eruptions, which have continued into historical time, have overcome the effects of erosion. In contrast, Recheschnoi volcano (right) has been inactive for longer periods of time and has been extensively dissected by glaciers. Only small pyroclastic cones and lava domes have erupted during the past 10,000 years.

Photo by Chris Nye, 1985 (Alaska Division of Geological & Geophysical Surveys).


Recheschnoi
The effects of erosion are visible in this view from the SW of two prominent stratovolcanoes on SW Umnak Island in the Aleutians. Mount Vsevidof (left) is a near-symmetrical volcano where frequent eruptions, which have continued into historical time, have overcome the effects of erosion. In contrast, Recheschnoi volcano (right) has been inactive for longer periods of time and has been extensively dissected by glaciers. Only small pyroclastic cones and lava domes have erupted during the past 10,000 years.

Photo by Chris Nye, 1985 (Alaska Division of Geological & Geophysical Surveys).


Baker
Mount Baker in the northern Cascades rises 1,500 m above a dissected basement complex of metamorphic and sedimentary rocks, exposed at Dock Butte in the foreground. On the left skyline is the glacially eroded core of the Pleistocene Black Buttes stratovolcano, a predecessor to Mount Baker. From left to right, the Deming, Easton, Squock, Talum, Boulder, and Park Glaciers drape the volcano's flanks.

Photo by Lee Siebert, 1990 (Smithsonian Institution).


Rainier
Stratovolcanoes, also referred to as composite volcanoes, are constructed of sequential layers of resistant lava flows and fragmented rock produced by explosive eruptions. An aerial view of the glacially dissected SW flank of Mount Rainier shows the layered interior of a stratovolcano.

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


Rainier
Stratovolcanoes are composed of accumulated layers of lava flows from effusive eruptions and fragmented rock from explosive eruptions. Glacier-clad Mount Rainier, seen here from the NW, is located in the northern Cascade Range. Most eruptions originate from a central conduit, which produces the common conical profile of stratovolcanoes, but flank eruptions also occur. Both isolated stratovolcanoes like Mount Rainier and compound volcanoes formed by overlapping cones are common.

Photo by Lee Siebert, 1983 (Smithsonian Institution).


Jefferson
Mount Jefferson has been inactive since the late Pleistocene and shows the effect of extensive erosion by glaciers. The Jefferson Park Glacier on the N flank in the foreground and the Whitewater Glacier on the E flank are the two largest on Jefferson.

Photo by Dan Miller, 1977 (U.S. Geological Survey).


Colima
A weak plume from the summit of Mexico's Colima volcano in 1992 with snow-capped Nevado de Colima to the left; view from the WSW. Frequent eruptions have been recorded at Colima since the 16th century. Eruptions have been dominated during the past century by lava effusion associated with lava dome growth, explosive eruptions of varying magnitude, and frequent pyroclastic flows.

Photo by Jim Luhr, 1992 (Smithsonian Institution).


Popocatepetl
The snow-capped peak of México's Popocatépetl stratovolcano rises above the Tlamacas region to its north. A faint plume rises from a deep summit crater. The sharp peak below the horizon at the right is Ventorrillo, the summit of the eroded Nexpayantla volcano that was a predecessor to Popocatépetl. Its steep cliffs expose the stratified, layered interior of a stratovolcano.

Photo by William Melson, 1968 (Smithsonian Institution)


Santa Maria
The interior of a stratovolcano is dramatically revealed in a 1-km-wide crater created on the SW flank of Guatemala's Santa María volcano during an eruption in 1902. The 1,200-m-high scarp exposes thin, light-colored lava flows that are interbedded with deposits of fragmented rock produced during growth of the volcano. The 1902 eruption was one of the world's largest during the 20th century.

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


Acatenango
Fuego (left) and Acatenango are two of several paired volcanoes in Guatemala. Activity from the Pleistocene-Holocene Acatenango has continued only sporadically into historical time, but Fuego is one of the most active volcanoes in Guatemala with about 60 historical eruptions.

Photo by Lee Siebert, 1988 (Smithsonian Institution).


Fuego
Fuego (left) and Acatenango are two of several paired volcanoes in Guatemala. Activity from the Pleistocene-Holocene Acatenango has continued only sporadically into historical time, but Fuego is one of the most active volcanoes in Guatemala with about 60 historical eruptions.

Photo by Lee Siebert, 1988 (Smithsonian Institution).


Las Pilas
Las Pilas stratovolcano, seen here from the S, is the most prominent feature of Nicaragua's Las Pilas volcanic complex. Las Pilas rises to 900 m above its base in the Nicaraguan depression. Its broad summit contains a 700-m-wide crater and a N-S fissure that formed during an eruption in 1952.

Photo by Bill Rose, 1967 (Michigan Technological University).


Mombacho
Mombacho is a stratovolcano on the shores of Lake Nicaragua that has undergone edifice collapse on several occasions. The NE-flank scarp was the source of a large debris avalanche that produced an arcuate peninsula and the Las Isletas chain of islands in Lake Nicaragua. The only reported historical activity was in 1570, when a debris avalanche destroyed a village on the S side of the volcano.

Photo by Jaime Incer, 1977.