How do volcanic eruptions occur?

Answer 1

Heat emanating from the hot/radioactive core of our planet can cause partial melting of some components of the upper mantle and crust of Earth. Where this happens the melt slowly aggregates/pools to form magma. As magma is a fluid, it can exert pressure in all directions as compared to a solid which when compressed in one direction resists deformation. This difference allows the fluid magma to force aside overlying solid rock and make its way upwards as structures called "Dykes".

The Dykes will rise to the surface and stop when the weight of the column of magma in the dyke equals the weight of and equal column of the crustal rocks (through which it is forcing itself). Thus depending on the density difference between the magma and crustal rocks, the Dyke could break through to the surface (pouring magma over the land) or stop at some position before the surface (both conditions are observable in the geological record).

However, most magmas contain a lot of dissolved volatile components (gasses) and as the Dyke nears the surface (and the pressure reduces), these come out of solution and the magma foams - like opening a bottle of Champagne.

The presence of the foam means that the overall density of the magma column is reduced and the magma often breaks through to the surface and beyond, allowing the magma to build a volcano (which is higher than the land around it) above the point of crustal exit.

The escaping gas is therefore the main cause of a volcanic eruption and is responsible for the explosions, eruption columns and lava fountains.

Answer 2

Source - Wikipedia A volcano is an opening, or rupture, in a planet's surface or crust, which allows hot, molten rock, ash and gases to escape from below the surface. Volcanic activity involving the extrusion of rock tends to form mountains or features like mountains over a period of time. Volcanoes are generally found where tectonic plates are pulled apart or come together. A mid-oceanic ridge, for example the Mid-Atlantic Ridge, has examples of volcanoes caused by "divergent tectonic plates" pulling apart; the Pacific Ring of Fire has examples of volcanoes caused by "convergent tectonic plates" coming together. By contrast, volcanoes are usually not created where two tectonic plates slide past one another. Volcanoes can also form where there is stretching and thinning of the Earth's crust (called "non-hotspot intraplate volcanism"), such as in the African Rift Valley, the Wells Gray-Clearwater Volcanic Field and the Rio Grande Rift in North America and the European Rhine Graben with its Eifel volcanoes. Volcanoes can be caused by "mantle plumes". These so-called "hotspots" , for example at Hawaii, can occur far from plate boundaries. Hotspot volcanoes are also found elsewhere in the solar system, especially on rocky planets and moons

Answer 3

A super volcano or super volcanic eruption is a volcanic eruption with ejecta greater than 1,000 cubic kilometers (240 cubic miles), which is substantially larger than any volcanic event in historic times.

Answer 4

Earthquakes and volcanic activity are phenomena that are studied under the scientific discipline of Plate Tectonics (a branch of Geology), which in general is a study of the continental plates (or slabs) that float upon the Earth's mantle.

By far, most earthquake and volcanic activity occur at or near the leading edges of plate movement. An example is found in the North American continent whose plate is moving in a roughly southwest direction. Therefore, it is the western boundary of the North American plate where we find it's leading edge, and which includes British Columbia, Washington, Oregon, California, and the west coast of Mexico.

Geologic stresses accumulate along the leading edge of the continental plates. They result from pressures associated with the direction of plate movement and its collision with other plates. Typically, these stresses will create fractures and deformities in the weaker areas of the plate, and will further cause movement (earthquake) such as uplift, slipping, and separation that can be catastrophic if severe enough. In addition, some earthquake events may be severe enough to allow hot molten rock (Magma) to rise through the weakened plate to form new volcanoes or cause existing volcanoes to "erupt".

Answer 5

a volcano erupts when the pressure in the ground comes to life l

Answer 6

Because the molten materials within the volcano are filled with gases that expand during the eruption.or...the magma is silica-rich

Answer 7

A volcano is explosive or quiet depending on the amount of viscosity in the volcano (how thick it is depending on the gases).

Answer 8

by magma and heat pressure

Answer 9

The Concentration Of Water in the Magma.