Magma is a molten rock, and the liquid is only below the surface of the earth, because once it reaches the surface it becomes lava. This substance is composed of a combination of dissolved gases, rock fragments and crystals and the liquid part of what is known as the melt. Due to its constitution at high pressures and temperatures, one of the richest in the world, ranging from 1,292 to 2,372 degrees Fahrenheit. This substance is often found in the magma chambers that feed the volcanoes. They can also intrude into nearby rocks and rise to the surface in the form of lava, or produce explosive expulsions of tephra.
How is magma formed?
The magma of the form and the sea in the lower part of the earth's crust or in the upper part of its mantle. It occurs when high levels of pressure combine with high temperatures, causing some of the rocks in the area to merge, and then this substance. Without this combination of pressure and heat, this substance does not work to form.
Magma cameras
This substance is most often found in magma chambers below the surface of the earth, basically underground pools of liquid rock. To maintain its shape, the liquid in these chambers must be exposed to constant high temperatures, in addition to a large amount of pressure. Because of this, the high pressure can eventually create a fracture in the surrounding rock, allowing the liquid to escape to the surface, where it becomes lava.
- Basalt: Magma occurs in three main types, all of which have different properties and are more common in different types of volcanoes and eruptions. The first type of this liquid is basalt, it is very low in silica and has a very low gas content. In addition, this liquid has a low viscosity. This type of liquid rock is formed at a much higher temperature than the other two varieties, at around 1200 degrees Celsius. It is more common in volcanic fields than other types of volcanoes, and is usually present in a stream of eruptions that produce thin lava flows that form shields.
- Andesite: Andesite magma occurs at a slightly lower temperature than basalt, which ranges from 800 to 1000 degrees Celsius. It also has a slightly higher silica and gas content and is moderately viscous compared to the low viscosity of liquid basalt rock. Andesite is more common in stratovolcanoes and will normally produce moderately explosive eruptions, which include liquid flow as well. These eruptions usually create thick, debris-filled lava flows.
- Rhyolite :The third type of magma is the rhyolite, and occurs at the lowest possible temperature for this substance, ranging between 750 and 850 degrees Celsius. It is the opposite of the basalt version, since it is rich in silica and has a high gas content. In addition, it has a high viscosity. This type of liquid is most commonly related to caldera volcanoes, which are distinguished by their extremely explosive eruptions. These eruptions generally produce pumice stones, ash fall and pyroclastic flows. In cases where this substance has a lower than normal gas content, the lava will begin to flow.
Basalt
Andresita
Rhyolite
Magma eruptions
Volcanic eruptions are often due to the accumulation of magma, which erupts. In general, these eruptions occur due to the high pressure derived from dissolved gases in the liquid rock. The gases usually remain dissolved because the pressure of the rocks that confine the substance is greater than the vapor pressure of the gas. If this balance is displaced, the result will be many small bubbles of gas filling the substance and trying to escape. Once the pressure becomes too large, the rash occurs.
https://www.google.co.ve/search?dcr=0&biw=1137&bih=735&tbm=isch&sa=1&ei=DTxyWoT9JIW85gLfmJbQDA&q=+Magma+eruptions&oq=+Magma+eruptions&gs_l=psy-ab.12...436671.450086.0.451828.8.7.0.0.0.0.711.1959.3-1j2j0j1.4.0....0...1c.1.64.psy-ab..6.1.706...0j0i67k1j0i30k1.0.Ufp_iIy6T44#imgrc=yo-8eb8Qsf55GM:
http://www.volcanpedia.com/magma/