Hot melted rocks collect under the Earth's surface and when the pressure becomes too hard, the Earth's skin breaks, and a volcano erupts. The melted rock inside the Earth is called magma, but when it comes out in an eruption, it is called lava.Know More
Plates are like the Earth's skin. They are called the Earth's mantle, and they float on the magma. Sometimes the plates separate, and that creates even more red-hot liquid rock. The Earth has to relieve the pressure in the form of a volcanic eruption. After the eruption, the lava spreads out, cools down and hardens into rock, but hot magma remains under the surface.
In the Pacific Ocean, 75 percent of all volcanoes are located in an area called the Ring of Fire, where two of the Earth's plates meet. Some volcanoes are cone-shaped mountains, some are flat-topped like mountain plateaus, some have fissure vents, which are cracks where the lava escapes, and others bulge like domes. There are even volcanoes on the ocean floor and under the icecaps in Iceland.
Volcanoes also happen on other planets in the solar system. On Mars there is a volcano called Olympus Mons, and it is 373 miles wide and 13 miles high. The most volcanic activity in the solar system is on one of Jupiter's moons.Learn more about Volcanoes
Volcanic eruptions can either be effusive or explosive. An effusive volcanic eruption occurs when the lava pours out onto the ground from the volcano's vent. When the molten rock or magma is thin and runny, gases can easily escape and the lava flows freely and travels far. An explosive volcanic eruption is caused by thick and sticky magma, which prevents gases from escaping and causes them to explode violently.Full Answer >
A volcano erupts through the build-up and release of pressure, whether that pressure is of its underlying magma, water or both. This release can be explosive, as it was in the famous eruption of Mt. Vesuvius that destroyed Pompeii, or it can be slow and effusive, as it is in the ongoing formation of the Hawaiian islands.Full Answer >
A volcanic eruption is caused by the injection of magma into a full magma chamber, the buoyancy of magma and the pressure exerted by the gases in the magma. The volcano simply acts as an opening through which magma and dissolved gases are discharged.Full Answer >
Shield volcanoes usually erupt with splattering liquid lava that fountains out and has little explosive potential. This forms some of the largest volcanoes on Earth with very gentle slopes, since the liquid water cannot build steeper slopes. This type of lava cools to form basalt rock.Full Answer >