Geography

Geography - Volcano

A Volcano is a rupture in the crust of earth through which lava, gases and ash escape on eruption. They are found where tectonic plates are diverging or converging. Most of the volcanoes are under water but some are on land.

Main types of Volcanoes
• Cinder Cone Volcano
 They form from pieces of scoria and pyroclastic that build up around the vent
 A cone-shaped hill is formed
 The eruptions of cinder cone volcano are short-lived
 Most of them erupt only once

• Shield Volcano
 They are in the form of shield of a warrior
 It is formed by low viscous lava that flow farther from a vent
 Lava is low in silica
 Frequent eruptions result in accumulation of sheets of lava
 Shield volcanoes are found in oceanic and continental settings

• Composite Volcano (Stratovolcano)
 It is a conical volcano formed by many layers of hardened lava and tephra
 Lavas are more viscous and high in silica
 Ash produced is hazardous
 Steeper than shield volcano

Some popular Volcanoes

Volcano	Location	Type of Volcano	Status
Mount Vesuvius	Gulf of Naples in Campania, Italy	Stratovolcano	Active
Mount Krakatoa	Sunda Strait between Java and Sumatra, Indonesia	Stratovolcano	Active
Mount St. Helens	Cougar, Washington State, USA	Stratovolcano	Active
Mount Tambora	West Nusa Tenggara, Indonesia	Stratovolcano	Active
Mauna Loa	Hawaii, USA	Shield	Active
Mount Fuji	Honshu, Japan	Stratovolcano	Active
Mount Kilauea	Hawaii, USA	Shield	Active
Mount Kilimanjaro	Tanzania	Stratovolcano	Dormant
Mount Rainier	Seattle, Washington State, USA	Stratovolcano	Active
Mount Stromboli	Tyrrhenian Sea, Italy	Stratovolcano	Active
Ojos del Salado	Argentina-Chile border	Stratovolcano	Dormant
Mount Etna	Sicily, Italy	Stratovolcano	Active
Mouna Kea	Hawaii, USA	Shield	Dormant

Volcanoes that produce very large amounts of volcanic deposit in a single explosion are called super volcanoes. It can cause a lot of devastation. Volcanoes on the ocean floor are called submarine volcanoes. Volcanoes that are under icecaps are subglacial volcanoes. Volcanoes that are created by the eruption of mud are mud volcanoes.

Volcanic eruptions caused by release of gas due to decompression are magmatic eruptions. The frequent short-lived eruptions which have moderate viscosities are called strombolian eruptions. The short-lived high viscosities explosions that destroy a central dome and eject lava are vulcanian eruptions. The eruptions with low gas, gentle and low level are Hawaiian eruptions. The eruptions that occur due to pressure build-up in superheated ground water is Phreatomagmatic eruption. The continuous and powerful eruption in which volcanic debris eject up to second layer of atmosphere, the stratosphere is called Plinian eruption.