VolcanoesVolcanoes

Natural processes & factors that create volcanic Natural processes & factors that create volcanic environments Volcanoes can be classified by the severity of environments Volcanoes can be classified by the severity of

their eruptions, which are usually named after famous their eruptions, which are usually named after famous volcanic explosions from the past or by the region they are volcanic explosions from the past or by the region they are

usually associated with, or by their physical attributes. usually associated with, or by their physical attributes.

Several classifications by severity are: Several classifications by severity are:

Hawaiian VolcanoesHawaiian Volcanoes

• little lava flows from small vent

Icelandic Volcano-lava gently flows Icelandic Volcano-lava gently flows on generally flat surface on generally flat surface

Krakatoan Volcano- extremely Krakatoan Volcano- extremely violent, often causes its peak to violent, often causes its peak to

detach detach

StrombolianStrombolian: small, frequent : small, frequent eruptionseruptions

VolcanianVolcanian: less frequent, more : less frequent, more violent Strombolian eruptions violent Strombolian eruptions

VesuvianVesuvian: violent eruptions after : violent eruptions after long periods of inactivity long periods of inactivity

PeleanPelean: powerful eruptions followed : powerful eruptions followed by flowing glowing lava by flowing glowing lava

PlinianPlinian: large amounts of lava and : large amounts of lava and pyroclastic are ejected pyroclastic are ejected

VOLCANIC LANDFORMSVOLCANIC LANDFORMS

• In addition to the first classification, volcanologists also group them into five major categories:

• Basic or shield volcanoes

Basic or shield volcanoes have broad, gentle slopes, similar to a warrior's shield, built from the buildup of cooled basaltic lava over thousands of years. They usually have nonviolent eruptions, letting its fluidic lava flow out in all directions from its vent or vents.

• Acid or dome volcanoes

Acid or dome volcanoes tend to have craggy, steep-sloped sides covered with rock debris. Its eruptions are characterized by viscous lava explosions, which allow its lava to flow for great distances and to spill over and around its vent. The increase in temperature causes the dome to expand while its outer lava cools. This growth causes the newly hardened surface to splinter, causing loose debris to fall from its sides, the reason for its appearance. These volcanoes are typically found near large composite volcanoes.

• Cinder and scoria volcanoes

The cinder and scoria volcano, also called ash and cinder, is the most basic type of volcano, with a round crater at its summit. The cinder or scoria is the result of gas-charged lava cooling in the air during an eruption. Such volcanoes usually never surpass a height of 1000 ft.

• Composite volcanoes or stratovolcanoes

Composite volcanoes or stratovolcanoes are one of the most majestic mountains in the world. At a staggering height of 8,000 feet above sea level, no other volcano can tower over these beauties. However, a rose does have its thorns. These volcanoes have explosive eruptions, with lava flowing from a crater in its summit, enough to damage whole cities. Composite volcanoes are known for its unique system of tunnels through which magma flows to the crater.

• Caldera volcanoes

Caldera is a bowl-shaped volcano depression, usually at least a mile in diameter. Despite its meek appearance, calderas are actually the most explosive of them all, having the force of several nuclear explosions. Hot springs, geysers, and such can be found near a caldera.