Shield volcano

A shield volcano is a special form of a volcano. The name comes from the shield -like arched shape of this volcano type.

Formation

The cause of the typical shape of the outflow is very viscous and thus fast flowing, low-gas lava. This is usually of basaltic composition and usually contains less than 52% silicon dioxide (SiO2). When outflow is about 1000 ° C to 1250 ° C hot. Origin of the transported magma is the upper mantle. The slope angle of shield volcanoes be due to the high flow rate of the lava (up to 60 km / h) only about 5 °, that is, it is consistently to very gently sloping, but extended cone. Shield volcanoes are designated according to their behavior as a red eruption volcanoes. They promote gigantic masses of low-viscosity ( red-hot ) lava effusion can emerge and spread widely even in shallow slope inclinations. Shield volcanoes are therefore not sublime pronounced. The ratio between the height and base diameter is usually only 1:20 to 1:10.

Occurrence

Most shield volcanoes are located within the lithospheric plates over hotspots ( eg Hawaii ) and at divergent plate boundaries on mid-ocean ridges ( eg Iceland ) or rift zones such as the Rift Valley. Of the 1,500 world's active volcanoes are shield volcanoes 180.

One of the famous shield volcanoes, the Mauna Loa in Hawaii. The shield volcanoes that have led to the construction of the Hawaiian Islands are the largest volcanoes in the world.

More active shield volcanoes are located on La Réunion, for example, the volcano Piton de la Fournaise.

The largest known shield volcano, and also the highest mountain of the Solar System is Olympus Mons on the planet Mars.