Magma can also push up under themiddle of a lithosphere plate, though this process is very less common than magma production around plate boundaries. Basically, this Interplate volcanic activity is take placed by unusually hot mantle material which is forming in the lower mantle and pushing up into the upper mantle. The mantle material, which forms a plume shape that is formed about 500 to 1000 km wide, also wells up to create a Hot Spot under a particular point on the earth surface. Because of the unusual heat of this mantle material, it melts solid The hot spot itself is stationary; but as a continental plate moves the hot spot, the magma will create a many string of volcanoes, which die out once they move past the Hot Spot. The Hawaii volcanoes were also created by such a hot spot, which appears to be at least 70 million years old.
Material and forming magma just under the earth’s crust.
WHAT HAPPENS TO MAGMA FORMED BY THESE PROCESSES?
We saw that magma which usually produced at ocean ridges just hardens to form new many crust, material, and therefore it doesn’t produce spewing land volcanoes. In a few continental ridge area, where always the magma does spew out onto land; But most land volcanoes are produced by subduction zone, volcanism and hot spot volcanism. It is the very prominent information of this topic.
When the solid rocks melt and change to more hot liquid rock material, it becomes very less dense than the surrounding solid rock. This difference of density, pushes the magma upward with very great force from the rocks, as we know the most common examples (for the same reason the Helium in a balloon pushes up through the denser surrounding air and oil pushes upward through denser surrounding water). As it pushes up, its intense heat also melts some neighboring rocks, which further also added to the magma mixture.
The magma keeps moving outward through the crust unless its upward pressure is exceeded as compare to the downward pressure of the surrounding solid rocks. At this stage, the magma collects in Magma chamber below the surface of the earth. And if the pressure of magma rises to a high enough level, or cracks open up in the crust, it will definitely cause the molten rock to spew out at the earth’s surface.
This is a stage where the flowing hot magma (now called Lava) forms a volcano. The structure of the volcano and the intensity of the volcanic eruption is independent on the different number of factors, But primarily related to the composition of the magma.
Lava contribute in formation of volcano
The lava that is created is usually the most important factor that contributes towards volcano morphology. And then the lava is created through the melting of molten rock in the mantle, which seeks towards earth’s surface through the different cracks. The viscosity and explosivity of the lava are generally the main elements that give the volcano its overall form. Therefore, the lava possesses high viscosity will generally form more of a bulky structure whereas lava that has the low viscosity will normally result in a smooth, Usually become the dome shaped formation.
Types of volcano
1: The shield volcano
The shield volcano is formed by the low viscous lava that travels far and wide for the creation of smooth dome structured volcano. The size of this type of volcano is dependent only on the number of eruptions that occur. more eruptions mean more lava that solidifies thus resulting in a built up of shield volcano.
2: Fissure volcano
Taking their name from the giant cracks in the earth’s crust from which they erupt, they are sometimes known as ‘linear volcano’ on the account of them it generally occurring along the fault lines. They through out large very amounts of lava which cools and solidifies after some time and also maintaining the flat shape. These volcanoes are generally found in clear islands and in also Hawaii, astride the Mid-Atlantic Ridge.
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