Stratovolcanoes form when a conduit grows out from a pocket of magma and eventually reaches the surface. Over millions of years and countless eruptions, the magma and ash cool and settle, forming the large, summit-like volcano. Stratovolcanoes grow larger than any of the other types of volcano and some reach more than a mile in height.
A stratovolcano, also known as a composite volcano, is a conical volcano built up by many layers (strata) of hardened lava, tephra, pumice and ash. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with a summit crater and periodic intervals of explosive eruptions and effusive eruptions, although some have collapsed summit craters called calderas.
Stratovolcanoes form through explosive eruptions depositing material near a central vent. The most common eruption types at stratovolcanoes are Strombolian, Vulcanian, and Plinian eruptions.
Generally speaking, the volcanoes that cause the most trouble for humankind are of the kind known as stratovolcanoes or composite volcanoes. Like other types of volcanoes, stratovolcanoes form around vents from which molten rock, or magma, reaches the Earth’s surface as lava.
Teachers Guide to Stratovolcanoes of the World : Introduction. What is a volcano? A volcano is simply a hole or vent in Earth's crust through which molten rock, steam and other gases come forth. Scientists group volcanoes into four main kinds--cinder cones, strato- or composite volcanoes, shield volcanoes, and lava domes.
How Are Stratovolcanoes formed? Less dense magma in the mantle rises up and melts through the crust. It gathers in a reservoir, a weak part of the rock, called a magma chamber. This creates pressure on the earth's crust. When the pressure becomes too large, the magma forces its
Stratovolcanoes tend to form at subduction zones, or convergent plate margins, where an oceanic plate slides beneath a continental plate and contributes to the rise of magma to the surface. At rift zones, or divergent margins, shield volcanoes tend to form as two oceanic plates pull slowly apart and magma effuses upward through the gap.
Strato Volcanoes comprise the largest percentage (~60%) of the Earth's individual volcanoes and most are characterized by eruptions of andesite and dacite - lavas that are cooler and more viscous than basalt.These more viscous lavas allow gas pressures to build up to high levels (they are effective "plugs" in the plumbing), therefore these volcanoes often suffer explosive eruptions.
Stratovolcanoes, or composite volcanoes, are similar to cinder cone volcanoes in terms of their shape, but that is one of their few similarities. These volcanoes have gentle lower slopes but much steeper upper slopes, creating an upwardly concave cone and generally have many distinct vents.
A stratovolcano is a tall, conical volcano composed of one layer of hardened lava, tephra, and volcanic ash. These volcanoes are characterized by a steep profile and periodic, explosive eruptions.