Under volcanism refers to all geological processes and phenomena associated with volcanoes in context, that is associated with the rise of magma from the mantle to the Earth's surface. The term " volcano " derives from the Italian island of Vulcano. This is one of the Aeolian Islands in the Tyrrhenian Sea. In Roman mythology, the island was considered the Forge of Vulcan, the Roman god of fire.
Plate tectonics and hot spots
Usually volcanism in tectonically active regions is bound as subduction zones or mid-ocean ridge - but it also occur magmas from greater depth of tectonic stationary hot spots (eg, Hawaii, Yellowstone ) from.
Role of magma
Under changes in the chemical composition (eg, water content) and the pressure ( pressure relief ) it comes to the partial melting of the rock ( magma ). The liquid material thereby accumulates usually in the so-called magma chamber. From this the present on the surface volcanoes are fed by narrow ways up.
Volcanism includes all forms of discharge of the material as a solid ( bomb, lapilli, pumice, ash ), liquid (lava, lahar, Geyser ) or gaseous (volcanic gas fumarole ) substances. It is not uncommon mixed forms of eruptive phenomena accompanying such as the devastating pyroclastic flows. The low equivalent are not plutonic rocks at the surface beaten magmas.
Volcanism on other planets
Volcanoes are among the most impressive manifestations of geological and geodynamic processes, not only on Earth but also on other planets and their moons in our solar system. There are several known active volcanoes outside of the earth; then sulfur volcanoes are located on Jupiter 's moon Io, cryovolcanoes on Neptune moon Triton and extinct volcanoes, for example, on Mars and Venus.
Man and volcanism
The volcanism has a share in the momentous natural disasters of the earth. He attributable to many of the massive upheavals in the earth's history, not least because of its significant influence on regional and global climate development with the resulting consequences such as famine. Volcanic disasters can affect the human population directly and indirectly, through destruction near an active volcano, or by global climatic changes and ash fall. At the same time, the products of volcanism, however, the livelihood provide wide range of people represent. Profitable by volcanic soils, building materials, geothermal energy and tourism About one tenth of the world's population lives under the direct application of active volcanoes. Watch Vulkanobservatorien, register and analyze the activity of active volcanoes in order to express forecasts and warnings can ( this is done in the last few decades largely with success).
Manifestations of volcanism: iron, lime and Schwefelausfällungen in the high temperature region Krýsuvík in Iceland
Signs of volcanic activity: sulfur deposits on the edge of Halemaumau crater of Kīlauea in Hawaii
Pyroclastic ash layers at Pinatubo
Eruption of the geyser Strokkur in Iceland