Minor types of Volcanoes

Aside from the main types of volcanoes, there are also other types of volcano which are the VOLCANIC DOMES, CALDERA, AND LAVA PLATEAU.

VOLCANIC DOMES

• also known " lava dome"

• is a roughly circular mound-shaped protrusion resulting from the slow extrusion of viscous lava from a volcano.

• are formed by viscous magma being erupted effusively onto the surface and then piling up around the vent.

• steep-sided mound that is formed when lava reaching the Earth’s surface

• volcanic domes may develop in the summit craters of volcanoes or completely away from any crater.

• extremely viscous lava that is like a toothpaste from a slightly squeezed tube

Saint Helens Volcano

Caldera

• a large, usually circular depression at the summit of a volcano

• most calderas are formed by subsidence or sinking of the central part of the volcano; a rare few are excavated by violent explosions.

• it forms large lakes

• a depression created after a volcano releases the majority of the contents of its magma chamber in an explosive eruption.

• a volcanic feature formed by the collapse of land surface after a gigantic volcanic eruption.

Taal Volcano, Philippines

LAVA PLATEAU

• are formed by highly fluid (runny) basaltic lava during numerous successive eruptions through numerous vents without violent explosions (quiet eruptions).

• many plateaus form as magma deep inside the Earth pushes toward the surface but fails to break through the crust.

• the eruptions are quiet because of low viscosity of lava,

• a wide, flat surface formed when a large amount of highly fluid lava flows over an area.

• these plateaus are often cut by deep canyons that expose the layers of rock.