The volcanoes and the safety precautions must be taken at the occurrence of the volcanoes .

Lava ( lava flows ) are molten materials mass that spreads on the volcanic sides .

There are thousands of volcanoes on the Earth's surface . But sixty one only of them are active as an evidence of the permanent activities and movement beneath the Earth's crust . 

You should know that Volcano is an opening in the Earth's crust which permits the passage of the trapped gases and the molten materials ( lava )  .

 

Causes of the volcano occurrence :

 lava flows cover and destruct whole towns and villages .

The direct cause of the volcano occurrence is the presence of weak parts in the Earth's crust , where molten materials are going out to the Earth's surface .

 

Parts of volcano :

 

It consists of three parts which are : 

 

1. The volcanic vent : It  is an opening lies at the top of the volcano .

    

2. Volcanic pipe ( or neck ) which is a cylindrical cavity that connects the Earth's interior with the surface , through which magma moves during its ascendence .

    

3. Volcano cone which is the body of the volcano . It consists of molten materials after their solidification and accumulation around the volcanic vent . 

    

Products of volcano :

 

The materials ejected during the volcanic eruption are fragmented materials , lava and the volcanic gases .

 

1. Fragmented materials which are materials that the volcano emanates . These materials are different in size ranging from big projectiles to volcanic ashes .

    

2. Lava ( or lava flows )  which are molten materials mass that spreads on the volcanic sides .

    

3. The volcanic gases which are the fused ( mixed ) gases with magma and the most important of them are water vapour and oxides of carbon , nitrogen and sulphur . 

    

Harms of volcanoes :

 

1. Lava and lava flows cover and destruct whole towns and villages .

    

2. Spreading of the poisonous gases and volcanic dusts  into far places and they cover large areas .

    

3. Fire catches in the forests and neighbouring places to the volcano and causes a lot of damage .

    

4. The volcanoes destroy the cultivated lands near it .

    

   

   Volcanoes form new islands in the seas , and they increase the area of lands .

Benefits of volcanoes : 

 

1. In some countries , the thermal energy resulted from volcano is used to produce electricity .

    

2. The volcanic projectiles and ashes form more fertile soil , So  the most important crops are produced  .

    

3. They form new islands in the seas , and increase the area of lands .

    

4. The volcanic rocks  are produced by the volcanoes , and they have great economic values . 

    

Safety and security precautions that must be taken at the occurrence of volcanoes :

 

• During the volcanoes , we must evaluate people from the neighbouring areas of the volcano  as soon as possible .

   

• To avoid poisonous gases emanated  from the volcanoes , People must take  account of the instructions of the forecasting of  the wind direction  .