free download PNG images :Volcano

A volcano is a rupture of the crust of a planetary mass object, such as the earth, that causes hot lava, ash, and gas to escape from magma chambers below the surface.

The reason for the occurrence of the earth's volcanoes is that its crust is divided into 17 main rigid tectonic plates, which float in the hot and soft layers of the mantle. As a result, volcanoes are usually found on earth where tectonic plates diverge or converge, while most are found underwater. For example, the mid Atlantic ridge, such as the mid Atlantic ridge, has volcanoes caused by divergent tectonic plates, while the Pacific Ring of fire has volcanoes caused by converging tectonic plates. Volcanoes may also form in places where the tectonic plates are spreading and thinning, such as the Great Rift Valley in East Africa and the Wells Gray Clearwater volcanic field, as well as the Rio Grande Rift Valley in North America. This type of volcanic activity belongs to the protection scope of "plate hypothesis" volcanic activity. [2] Volcanic activity away from the plate boundary is also interpreted as a mantle plume. These so-called "hot spots" (Hawaii, for example) are assumed to be the rising chassis of magma from the core mantle boundary up to 3000 kilometers from the earth. Volcanoes usually do not form where two tectonic plates slide over each other.

Volcanic eruption will not only be near the eruption, but also bring many hazards. One such hazard is that volcanic ash may pose a threat to aircraft, especially jet engine aircraft, in which case the particles of volcanic ash will melt due to high operating temperature; then, the melted particles will adhere to the turbine blades and change their shape, thus damaging the operation of the turbine. Volcanic eruptions affect temperature because ash and sulfuric acid droplets block the sun and cool the earth's lower atmosphere (or troposphere); however, they also absorb heat from the earth's radiation, warming the upper atmosphere (or stratosphere). Historically, the winter of the volcano caused catastrophic famine.