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Volcanoes

Introduction
The volcanoes of the unique natural phenomena, which drew the attention of rights since ancient times and they play a great role in geological processes that affect the history of the evolution of the earth's crust and shape. This is because the most affected parts of the earth's crust and underwent operations Alandfaip in composition to the contribution of operations Alandfaip. According to the study of volcanoes in the identification of centers of earthquakes and volcanoes, study the branch of geology, which has become known as a stand-alone Volcanology Volcanology. And volcanic eruptions are accompanied by metals and raw materials are very important in economic terms.


The definition of the volcano
The volcano is a place out or emits materials Alzirip warm with fumes and gases associated with the depth of the earth's crust and occurs during the craters or cracks. And accumulate magma flow or by type to form the different land forms, including conical hills or mountains, volcanic high.


Parts of the volcanoes
Consists of

Mount conical
Is composed of rocky debris or hardened lava. A material thrown from the volcano crater and it was all or some of them in the molten state.

Nozzle
It is a cavity nearly round shape at the top of the cone, wider ranges between
A few thousand meters. And emerge from the crater at intervals of gas and the masses of rock, shells, lava and molten materials (lava) may have a volcano crater more than secondary to the main crater at the top as you can see in the figure:

Chimney or bronchus
A channel extending from the bottom of the crater to the bottom of the oven where related to magma underground. And rush through which volcanic material to the nozzle. And sometimes known as the neck of the volcano.
In addition to the main chimney, it may be related to the volcano several stacks Balfohat secondary.



Types of volcanic material

Out of volcanic rock debris while Thoradtha solid and liquid substances

Rock debris
Emerge as a result of volcanic eruptions rocky debris into various types and sizes are usually in the first period of volcanic eruptions. And rock debris derived from the rigid crust extracted from the walls of the neck as a result of payment of lava and gaseous substances emanating from the magma force and violence and rock debris composed of different materials in the sizes of rock masses, shells and pebbles, and sand and volcanic dust

Gas
Graduated from the volcanic activity during the gas water vapor, which pops up great quantities of a component of the huge clouds mingle with the dust and other gases. And thickens, causing the vapors to the heavy rain falling in the vicinity of the volcano. Accompanied by explosions and rainfall occurs, electric lights arise from the friction of volcanic ash particles with each other and as a result of air turbulence, and except for high temperature water vapor, volcano spews the most important multi-gas hydrogen, chlorine, sulfur, nitrogen, carbon and oxygen.

Lava
Is the liquid blocks "instead of volcanoes, with a temperature between 1000 and 1200. And lava emerges from the crater, and bursting through the cracks and fractures in the aspects of the volcanic cone, the fractures created by the explosions and the magma pressure blocks, and stop nature of the lava and appearance of the chemical composition of the magma blocks, which emits a two




And two lava

Lava light, light-colored
This is characterized by bone viscosity, and then they slow flow like lava that emanated from the volcano Billy (in the Islands Almrtnik in the Caribbean) in 1902 was thick sticky so it has not any time to move, and took accumulate and rise up consists of the tower above the crater reached a height of about 300 m , and soon after that to break and crash as a result of explosions caused by the release of gas

LAVA heavy dark
It is Ava basaltic, and characterized as a liquid and moving to a large degree, the flow in the form of streams on the slopes of the volcano, while the stems of these lava through fractions of great extension, it spread over vast areas made up of hills spacious, like the Ethiopian highlands and the Deccan plateau, India and the Golan Colombia in North America.





Forms of volcanoes

Volcanic rock debris
Different form depending on the volcanic cone material that consists of them. If the cone is composed entirely of rock debris, we found high steep for the space occupied by the base. Here we find the gradient of 30 degrees was sometimes up to 40 degrees Celsius and these forms usually arise as a result of volcanic eruptions. The Islands of Indonesia.

Volcanic plateau
Arise as a result of exit and lava accumulation around the main crater and this low-rise look for the large area occupied by the rules. And look peaks like Bhiab convex Thdba Hina hence the name volcanoes Plateau has arisen cones of flow Mshorat lava extreme heat and great liquidity and that has spread over large areas and is the volcanic plateau best represented in the volcanoes of the Hawaiian islands Kbarakan Monallowa with a height of 4100 m and it seems like spacious dome descend steeper easy easy.

Volcanoes Layering
Volcanoes Layering is a common type of existence, which is in its center and is composed of former types of materials Mkrotadtha rock debris and lava flows, directed by the volcano eruption, while restless.
And be Alloafez that come out of the volcano during eruptions of successive layers, one above another, and Section consists of coarse materials and another section of the material accurate, and between this and that overlap in the form of lava a few bars of fish. From this arises a kind of Layering in the installation of the cone This figure represents the Mayon Volcano Islands, the Philippines, more active at the present time.


The geographical distribution of volcanoes

Volcanoes are spread over long ranges on the surface of the land shown

1 - range that surrounds the coasts of the Pacific, which is sometimes known as Ring of Fire, it runs on the eastern shores of the Pacific over the Andes to Central America and Mexico, and on the heights of western North America to the Aleutian Islands and from there to the coast of East Asia to the islands of Japan, the Philippines and then to Islands of Indonesia and New Zealand.

2 - There are many volcanoes in the Pacific Ocean itself and some of them grew up in a huge great hall and appeared towering above the water level. Including the volcanoes of the Hawaiian islands, which were based norms in the ocean at a depth of approximately 5000 m, and rise above the surface of water more than 4000 m, bringing the total height from the bottom of the ocean to the peaks of about 9000 m

3 - South Europe, overlooking the Mediterranean Sea and its adjacent islands. The most active volcanoes here Vesuvius near Naples, Italy, and Sicily, Aetna Islands Mpule Astro (the Lighthouse Mediterranean) in the islands of Lipari.

4 - Heights, West Asia and months and Ararat volcanoes Aliuzenz.

5 - is east of Africa and the Kilimanjaro months Brkinh
.



Effects of volcanoes
In the formation of the Earth's surface

Of the foregoing, we can discern the effects of volcanoes in the formation of the Earth's surface are created majestic mountains and plateaus spacious. When subsided arise in the cavities in the bodies of their pores Lakes rainforest.

Human activity
Strange that the man was playing next to residential volcanoes in order to be safe from the dangers, seen live near them, but also on the slopes. Fberkan Vesuvius, surrounded by villages and towns and covered with gardens and fruit orchards and vineyards spread over all of its aspects until near the top. The agriculture is also on the slopes of a volcano (twelve) on the island of Sicily, until a height of 1200 m in fertile soil is composed of black basalt that spilled over the region during historical times.

These volcanoes and unforgiving as it arises from the time of destroying another village or another can rest along the main road on the lower slopes of a volcano, and at the end of twelve flows of lava flowing is evidence to suggest an eternal constant danger posed to the region.

The famous island of Java Berakinh rebellious and active volcanoes than in fact all volcanoes of the world in the amount of spills and Alloafez which were founded since 1500, however, we find the island full of population, they are denser parts of the world agricultural population for the area is inhabited by about 75 million people, because as we have said to fertility volcanic soils, has been established by the Department of Volcanology and function predict volcanic eruptions and warn the population before the volcanic eruptions, which reduces the risk of their occurrence