The causes of volcanic formation

Volcano (Volcano) from the Italian term "Vulcano", was Italy in the Mediterranean Lipari Islands (Lipari Islands) the name of a volcano, and later became a synonym volcano. Vulcan in ancient Rome and the middle finger text 』『 Vulcan. 

 Volcanic movements and the Earth's interior melt the liquid, the drive is closely related to the plate movement. 

 Plate movement 

 Earth's surface and shallow parts can be divided into a number of large plates. Plate, including the crust and upper mantle, which is equivalent to the lithosphere, about 100 kilometers thick. Cubicles each plate boundary in its relative movement to do: First, the expansion of (Divergence), First subduction (Convergence); This is the plate movement. Volcanic activity generally occurs in places where the transfer plate or in the vicinity, mainly divided into three parts: 

 Plate expansion zones: the Pacific ridge belt, the Atlantic Ocean and the Indian Ocean ridge with mid-ocean ridge volcanic belt are here. 

 Plate subduction zone: circum-Pacific belt and the Mediterranean volcanic belt occurred in the vicinity. 

 Hot spots: located in the upper mantle in the magma may be generated when the plates so the level of movement, after the volcanic hot spot will be generated, this will cause a succession of a series of volcanoes, and volcanic generated farther away from the hot spots are getting old. Islands such as Hawaii volcano. 

 And plate movement makes magma generate and increase in the ground caused by volcanic outflow. 

 Magma generation and outflow 

 Refers to the volcanic activity deep underground magma flow to the ground phenomenon. And all we can see the volcanic activity, but from the beginning of magma into the ground to stop the activities during this period of the phenomena it. The activities carried out under the ground must use other methods to speculate. The following is a magma underground activities: 

 Magma generated places: the majority of magma generated in the lower crust to between the upper mantle (about 20-200 km Inter), but more in the upper mantle. 

 Magma generated conditions: the Earth's interior temperature distribution in the ground temperature of 200 kilometers, it is estimated that in 1200 ℃ to 1600 ℃ around. In this temperature, the department's ultrabasic silicate minerals most of which do not melt. Because if the melting, the temperature must increase, otherwise the melting point of silicate minerals will be reduced. Magma generated by the reasons therefore are: the temperature increased, the water content increased, the pressure to reduce such. Temperature increased the way: The letter of thermal convection, in part, the letter can temperature; some stress due in part to strengthen the letter of the temperature. Pressure mantle silicate minerals will reduce the melting point lower mantle within the water will also increase the melting point of silicate minerals, such as lower. Earth around the magma generated is not the same as the reasons, that is, around the magma generation mechanism. Under the magma ocean ridges, the magma under the continental margin, island arc magma and the mainland under the magma, and its formation mechanism are different from each other. 

 Rise with the composition of magma changes: magma pressure inside the shelters if more than the pressure of rock, the magma on the rise along the cracks to the ground. Magma on the rise during the period, with the temperature and pressure of the lower part of the beginning of the crystallization of minerals, but also began to change in composition of magma. The results of flow to the ground, it generated a variety of igneous rock. For the rising magma mechanism and composition changes (differentiation) is also a variety of views, such as rising magma generated directly to the surface,? Beckmannia b rise during the magma composition of some change, some will not change; magma (original magma) began to rise after generation, but in mid-stay for some time (the formation of the so-called magma library, Magma reservoir) after rising to the surface, in such cases, the magma composition in the original magma rising in the magma library or second rise are likely to change. As the number of magma stay? M component change can do a variety of places to consider.