EMS- Managing natural hazards, page no 139

What is a earthquake and volcanic eruptions:

Earthquakes: An earthquake refers to the shaking of the earth's surface caused by a sudden release of energy within the earth's crust.

Volcanic eruptions: an eruption of molten rock, hot rock fragments, and hot gases through a volcano, which is a vent in a planet's or satellite's crust. Volcanic eruptions can cause disastrous loss of life and property.

How are they caused:

• Causes of earthquakes: Earthquakes are caused by sudden tectonic movements in the Earth's crust. The main cause is that when tectonic plates, one rides over the other, causing orogeny collide (mountain building), earthquakes. The largest fault surfaces on Earth are formed due to boundaries between moving plates.

• Causes of volcanic eruptions: The melted substance is light in weight. This thin lava comes up to the crust since it can float easily. Since the density of the magma between the area of its creation and the crust is less than the enclosed rocks, the magma gets to the surface and bursts.

  
  

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