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.Continue Reading
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 about Volcanoes
Lava, or molten rock that erupts from volcanoes and fissures, is so hot because rock only melts at very high heat. Typically, only a small portion of any rock melts, even at depths of around 93 miles inside the Earth.Full Answer >
Volcanoes are formed from previous magma (molten rock from the Earth's interior) emissions that slowly cool and harden over time, forming a visible vent in the Earth's surface. When magma and gas from the Earth's mantle (a region of molten rock that exists between Earth's core and surface) build enough pressure within the vent, a volcanic eruption occurs and causes hot magma, gas and ash to spewed onto the Earth's surface and atmosphere at temperatures reaching 2,000 degrees Fahrenheit.Full Answer >
A magma chamber is a structure made up of solidified crystal mush and molten rock located below the surface of the Earth. When a magma chamber solidifies and cools, it is known as a pluton.Full Answer >
Volcanic arcs are formed when an oceanic plate is forced under a continental plate and the water-soaked crust melts as it's forced below the ocean floor, creating magma that feeds volcanoes on the continental side of the subduction zone. Stratovolcanoes are created in an arc around the subduction zone. The geologic phenomenon occurs all around the world but is most commonly seen around the Pacific Ocean tectonic plate in a formation known as the ring of fire.Full Answer >