Volcanoes occur when molten rock from underneath the Earth's crust rises up. This molten rock comes from the mantle, not from the Earth's core. Because of plate tectonics, volcanoes can form relatively quickly.Know More
The interior of the Earth is so hot that rocks are melted, and much of this heat radiates to the mantle as well. The mantle itself is so hot that efforts to drill into it have failed as drilling equipment melts when it comes into contact with it. The mantle is closer than many imagine; the Earth's crust is only about 35 kilometers deep, but its depth varies considerably.
When pressure in the mantle builds, molten rock can be forced to the surface. Over a relatively short period of time, this can cause a volcano to form. This pressure if often the result of the Earth's plates pushing against each other, which is why volcanoes are often found in areas where earthquakes appear regularly.
The core of the Earth is not its only source of heat. Radioactive decay underground creates a significant amount of heat as well, and this heat can influence the formation of volcanoes. The total heat created by this decay, however is far less that the residual heat in the core of the planet.Learn more in Volcanoes
Volcanoes form at two different types of boundaries between tectonic plates on the Earth's crust: subducting and constructive. Subducting boundaries appear where one plate slides beneath the surface of the other while constructive boundaries slide along one another from side to side rather than colliding. Also, other hot spots on the crust lead to volcano formation as well.Full Answer >
Commonly, volcanoes form at points where the Earth's crust is thinnest. This is normally near fault lines, but has been known to occur in the middle of tectonic plates or even in subduction zones, where one plate is pushing another plate down under it.Full Answer >
Volcanoes are vents in the Earth's crust that allow liquid lava from inside the planet to travel to the surface. According to Reference.com, the word "volcano" applies to both the vent and the cylindrical cone the lava forms.Full Answer >
Volcanoes are formed when the molten rocks and gases under the earth break through the crust and erupt. A volcano can be a crack, a dome or a mountain with a crater at the top.Full Answer >