Types of Volcanic Landform: Composite Volcano

Mount Fuji - or Fuji-san in Japanese

Composite Volcano is also known as a stratovolcano. These volcanoes form tall, conical shaped mountains. Most of the Earth's active volcanoes have formed a ring around the Pacific Ocean. There are 452 stratovolcanoes in the Pacific Ring of Fire. The volcanoes are located in a volcanic arc on the continental side of subduction zones. they are built of alternating layers of lava and pyroclastic materials. Other the name "strata" meaning "layers"

Composite volcanoes are constructed from multiple eruptions, sometimes recurring over hundreds of thousands of years, sometimes over a few hundred. Andesite magma, the most common but not the only magma type forming composite cones, produces lava more brittle than basaltic lava because of its higher viscosity. Although andesitic composite cones are constructed dominantly of fragmental debris, some of the magma intrudes the cones as dike or sills. In this way, multiple intrusive events build a structural framework that knits together the voluminous accumulation of volcanic rubble, which can stand higher than cones composed solely of fragmental material. Composite cones can grow to such heights that their slopes become unstable and susceptible to collapse from the pull of gravity. Famous examples of composite cones are Mayon Volcano Philippines, Mount Fuji in Japan, and Mount Rainier, Washington, U.S.A. Some composite volcanoes attain two to three thousandmeters in height above their bases. Most composite volcanoes occur in chains and are separated by several tens of kilometers. There are numerous composite volcano chains on earth, notably around the Pacific rim, known as the "Rim of Fire".

A stratovolcano, also known as a composite volcano,[1] is a conical volcano built up by many layers (strata) of hardened lava, tephra, pumice, and volcanic ash. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile and periodic explosive eruptions and effusive eruptions, although some have collapsed craters called calderas. The lava flowing from stratovolcanoes typically cools and hardens before spreading far due to high viscosity. The magma forming this lava is often felsic, having high-to-intermediate levels of silica (as in rhyolite, dacite, or andesite), with lesser amounts of less-viscous mafic magma. Extensive felsic lava flows are uncommon, but have travelled as far as 15 km (9.3 mi).[2]

Stratovolcanoes are sometimes called "composite volcanoes" because of their composite layered structure built up from sequential outpourings of eruptive materials. They are among the most common types of volcanoes, in contrast to the less common shield volcanoes. Two famous stratovolcanoes are Krakatoa, best known for its catastrophic eruption in 1883 and Vesuvius, famous for its destruction of the towns Pompeii and Herculaneum in 79 CE. Both eruptions claimed thousands of lives. In modern times, Mount Saint Helens and Mount Pinatubo have erupted catastrophically.

Charateristics of Composite Volcano or Stratovolcano

• Composite volcanoes are made up of alternating layers of lava and ash (other volcanoes just consist of lava).

• They are usually found at destructive or compressional boundaries.

• The eruptions from these volcanoes may be a pyroclastic flow rather than a lava flow. A pyroclastic flow is a mixture of hot steam, ash, rock and dust.

• A pyroclastic flow can roll down the sides of a volcano at very high speeds and with temperatures of over 400°C.

Its shape is up to 30 degrees at the summit and 5 degrees at the base

• Have the most symmetrical con shapes of all types of volcanoes

• These volcanoes are formed by very viscous lava that can plug its throat. this plug in the throat can cause pressure to built up in the magma chamber,causing it to erupt in an explosive manner

Composition of stratovolcanoes

Stratovolcanoes are typically composed of layers of pyroclastic material. The layers that form the mountain are lava, volcanic ash, tephra, and pumice. Andesite, dacite and rhyolite lavas erupted by these volcanoes have a high percentage of quartz and feldspar minerals.

• Minerals in lavas

The minerals in these lavas can be highly explosive because the gases in the magma cannot easily escape. The lava is less fluid and forms thick lava flows on the sides of the volcano. Sometimes the lavas form small dome volcanoes over the vent in the crater of a stratovolcano or on its steep sides.

• Eruptions of statovolcanoes

Stratovolcanoes erupt less frequently than shield volcanoes which have formed over hot spots. The lava is less fluid and often erupts with explosive eruptions that produce deadly pyroclastic flows.

• Krakatoa eruption

The eruptions of Krakatoa in 1883, Mount Saint Helens in 1980 and Mount Pinatubo in 1992 were examples of large volcanic eruptions by stratovolcanoes.

These are the famous examples of Composite Volcano

1.Mount St. Helens or Louwala-Clough (known as Lawetlat'la to the indigenous Cowlitz people, and Loowit to the Klickitat) is an active stratovolcano located in Skamania County, Washington, in the Pacific Northwest region of the United States. It is 96 miles (154 km) south of Seattle, Washington, and 50 miles (80 km) northeast of Portland, Oregon. Mount St. Helens takes its English name from the British diplomat Lord St Helens, a friend of explorer George Vancouver who made a survey of the area in the late 18th century.[1] The volcano is located in the Cascade Range and is part of the Cascade Volcanic Arc, a segment of Mt. St. Helen in Slamania Country,Washington the Pacific Ring of Fire that includes over 160 active volcanoes. This volcano is well known for its ash explosions and pyroclastic flows.

Mount St. Helens is most notorious for its major 1980 eruption, the deadliest and most economically destructive volcanic event in the history of the United States.[2] Fifty-seven people were killed; 250 homes, 47 bridges, 15 miles (24 km) of railways, and 185 miles (298 km) of highway were destroyed. A massive debris avalanche triggered by an earthquake measuring 5.1 on the Richter scale caused an eruption[3] that reduced the elevation of the mountain's summit from 9,677 ft (2,950 m) to 8,363 ft (2,549 m), leaving a 1 mile (1.6 km) wide horseshoe-shaped crater.[4] The debris avalanche was up to 0.7 cubic miles (2.9 km3) in volume. The Mount St. Helens National Volcanic Monumentwas created to preserve the volcano and allow for its aftermath to be scientifically studied.

As with most other volcanoes in the Cascade Range, Mount St. Helens is a large eruptive cone consisting of lavarock interlayered with ash, pumice, and other deposits. The mountain includes layers of basalt and andesite through which several domes of dacite lava have erupted. The largest of the dacite domes formed the previous summit, and off its northern flank sat the smaller Goat Rocks dome. Both were destroyed in the 1980 eruption.

2.Mayon (Central Bikol: Bulkan Mayon, Filipino: Bulkang Mayon), also known as Mayon Volcano or Mount Mayon, is an active stratovolcano in the province of Albay in Bicol Region, on the large island of Luzon in the Philippines. Renowned as the "perfect cone" because of its symmetric conical shape, the volcano and its surrounding landscape was declared a national park on July 20 of 1938, the first in the nation. It was reclassified a Natural Park and renamed as the Mayon Volcano Natural Park in 2000.[3] Local folklore refers to the volcano being named after the legendary princess-heroine Daragang Magayon (English: Beautiful Lady)

Mt. Mayon in the Province of Albay, Bicol,Philippines

3. Mount Fuji, located on Honshu Island, is the highest mountain in Japan at 3,776.24 m (12,389 ft).[1] It is an active stratovolcano that last erupted in 1707–1708,[5][6] Mount Fuji lies about 100 kilometres (60 mi) south-west of Tokyo, and can be seen from there on a clear day. Mount Fuji's exceptionally symmetrical cone, which is snow-capped for about 5 months a year, is a well-known symbol of Japan and it is frequently depicted in art and photographs, as well as visited by sightseers and climbers.[7]

Mount Fuji is one of Japan's "Three Holy Mountains" (三霊山 Sanreizan) along with Mount Tate and Mount Haku. It is also a Special Place

Scenic Beauty and one of Japan. Mt. Fuji in Japan It was added to the World Heritage List as a Cultura.According to UNESCO, Mount Fuji has "inspired artists and poets and been the object of pilgrimage for centuries". UNESCO recognizes 25 sites of cultural interest within the Mt. Fuji locality. These 25 locations include the mountain and the shrine, Fujisan Hongū Sengen Taisha, often shortened as Fuji-San.

The base of the volcano is about 78 miles (125 km) in circumference and has a diameter of some 25 to 30 miles (40 to 50 km). At the summit of Mount Fuji the crater spans about 1,600 feet (500 metres) in surface diameter and sinks to a depth of about 820 feet (250 metres). Around the jagged edges of the crater are eight peaks—Oshaidake, Izudake, Jojudake, Komagatake, Mushimatake, Kengamme, Hukusandake, and Kukushidake.

On the northern slopes of Mount Fuji lie the Fuji Five Lakes (Fuji Goko), comprising, east to west, Lake Yamanaka, Lake Kawaguchi, Lake Sai, Lake Shōji, and Lake Motosu, all formed by the damming effects of lava flows. The lowest, Lake Kawaguchi, at 2,726 feet (831 metres), is noted for the inverted reflection of Mount Fuji on its still waters. Tourism in the area is highly developed, with Lake Yamanaka, the largest of the lakes (at 2.5 square miles [6.4 square km]), being the focus of the most popular resort area. Southeast of Mount Fuji is the wooded volcanic Hakone region, well known for its hot-springs resorts at Yumoto and Gōra.

References

http://www.kids-fun-science.com/composite-volcano.html

https://en.wikipedia.org/wiki/Stratovolcano

http://www.bbc.co.uk/schools/gcsebitesize/geography/natural_hazards/volcanoes_rev3.shtml https://en.wikipedia.org/wiki/Mayon

http://www.planetware.com/japan/mount-fuji-jpn-kn-fuji.htm

https://en.wikipedia.org/wiki/Mount_St._Helens

https://en.wikipedia.org/wiki/Mount_Fuji

https://www.britannica.com/place/Mount-Fuji