Land destruction makes the worst destruction in the world. It affects every living things directly, without any warning. They move the ground, shake the ground and make a big hole in the ground. There are a lot of natural destrution, however, the most fear destructions is the volcano.

VOLCANOES

A volcano is a vent in the earth through which hot gases and molten rock rise to the surface. A coneshaped mountain of erupted material around such a vent is also called a volcano. It consists of a fissure in the earth's crust, above which a cone of volcanic material has accumulated. At the top of the cone is a bowl-shaped vent called a crater. The cone is formed by the deposition of molten or solid matter that flows or is ejected through the vent from the interior of the earth.

Formation
Volcanoes are formed by rising magma. Magma contains gases such as carbon dioxide and sulphur dioxide. Volcanic activities occur frequently at areas of plate boundaries. Plate tectonics causes movement in the plates and crust, resulting in cracks being formed. These cracks allows the pressure underneath the crust to push the magma, or sometimes water and steam, up the crust. Volcanic materials that are poured out through the vent fall back near it. The accumulation of the materials around the vent will build up a conical-shaped or dome-shaped volcano.

Types of volcano

Ash and cinder Volcano

It is a steep-sided symmetrical conical volcano formed from hot ash and red-hot cinders. The volcanic materials are thrown out to a great heights and they drop back around the vent. Successive eruptions build up a volcano of ash and cinders. The volcano grows rapidly but it is generally not very high. Ash and cinder volcanoes are usually found in groups.

Lava Volcano

The shape of a lava volcano depends on the viscosity of the lava. There are two kinds of lava volcano:

• Basic Lava Volcano (shield volcano)
  Fluid basic lava gives rise to gently-sloping shield volcanoes.
  There is no violent eruption.
  
  
• Acid Lava Volcano (dome volcano)
  Viscous acid lava solidifies quickly and
  forms an acid lava volcano with steep
  convex sides.

Composite Volcano

It is the highest and most common volcano. It consists of alternate layers of ash and cinders, and viscous acid lava. It is steep towards the top and gentler at the base.