A volcano on Earth crust is a vent through which lava, ash, and gases erupt. A volcano mountain forms due to the accumulation of these eruptive substances in the crust.
Volcanoes have existed on Earth since long, causing disasters and mass extinctions. It believed that volcanoes have existed on other planets also like the moon and Mars have long been dormant. On Jupiter’s moon, volcanoes are very active. Research is carried out in different part of worlds for prediction of volcanic eruptions before it happens on Earth by analysing gases and crystals linked with volcanoes. According to U.S. Geological Survey, the Earth’s crust is 5 to 60 kilometers thick. There are seven main and 152 smaller pieces which are called tectonic plates. These tectonic plates float on earth layer known as magma. There are a semi-liquid rock and dissolved gases at the boundaries of these plates. Magma is lighter than the surrounding solid rock which allows its way up through cracks and erupts. Magma can explode from the vent, and its eruption is called lava.
Principal Types Of volcanoes
According to San Diego State University, the most common type of volcano is Cinder cone volcanoes. Lava ejected from a single vent is termed as tephra. According to the U.S. Geological Survey, the lava cools rapidly and fall as cinders and forming a crater at the summit. Cinder cone volcanoes are small and ranging from 300 feet to 1,200 feet (366 meters). It can take a few months or years to build.
Stratovolcanoes are made of layers consisting of lava, ash, and blocks of unmelted stone. They are also known as composite volcanoes. Their height rises to 8,000 feet, and they are taller than cinder cones. Stratovolcanoes form due to the conduit system of vents developing from a magma reservoir.
Stratovolcanoes erupt with great violence and can create more disaster. Gases built pressure in the magma chamber. After magma reaches the conduits, it releases the pressure, and the gases explode. This type of volcanoes can blow sides of the cone and summit crater.
On May 18, 1980, Mount St. Helens volcano, in Washington state, is a stratovolcano that erupted. The volcanic eruption destroyed approximately 596 square kilometers of forest, and approx 60 peoples died. According to the geological survey, 520 million tons of ash reached the United States and caused complete darkness in Spokane, Washington.
They are big and sloppy that is built of very thin lava. The lava comes out in all directions from a central core. Its wider bases with steeper middle slopes and a flatter summit allow the flow of lava. They are not explosive, but liquid overflows around the edges.
According to the U.S. Geological Survey, Mauna Loa in Hawaii is the largest volcano, is a shield volcano. It is about 55,770 feet taller. It is also one among the most active volcanoes on Earth and is erupted lastly in 1984.