Earthquakes and Volcanoes.

Earthquakes

An earthquake occurs when there is a sudden release of energy that has been built up in an area in the Earth's crust or upper mantle, like plate boundaries, where convergence, divergence and transform movements are found. Plate boundaries are zones of instability and movement; therefore, earthquakes are common along these lines of division.

All types of plate movements, diverging, converging and transforming, causes earthquakes. This is because, when two plates undergo such movements which are not smooth, the rocks in them get 'stuck' due to the tremendous friction. However, the magma still continues to drag and pull these two plates. A lot of stress builds up at these zones, and finally, it causes the rocks to jerk themselves to be free of this position. This jerking movement can range from a several centimeters to a few meters, and results in the release of the energy stored when they were in their locked position. This causes seismic waves which makes the ground vibrate a little or veer violently, depending on the magnitude, causing an earthquake.

Earthquakes occur on plate margins.

As one plate rubs against the other, pressure builds up and when this pressure reaches its maximum it releases suddenly and causes an earthquake.

Earthquakes can have disastrous effects but this is dependent on how rich the country is and how well it has prepared.

Effects of an earthquake: gas pipes fracture causing fires, buildings collapse, sewage pipes broken - risk of disease.

There are 3 main types of earthquakes:

Active - They can erupt at any time.

Dormant - They have not erupted recently (within the last 2000 years).

Extinct - They will ...

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Earthquakes occur on plate margins.

As one plate rubs against the other, pressure builds up and when this pressure reaches its maximum it releases suddenly and causes an earthquake.

Earthquakes can have disastrous effects but this is dependent on how rich the country is and how well it has prepared.

Effects of an earthquake: gas pipes fracture causing fires, buildings collapse, sewage pipes broken - risk of disease.

There are 3 main types of earthquakes:

Active - They can erupt at any time.

Dormant - They have not erupted recently (within the last 2000 years).

Extinct - They will not erupt again.

Although earthquakes cause deaths and there are man reasons not to live near earthquakes (on plate boundaries) there are advantages such as the soil is often fertile

Volcanic Activities

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 allow the pressure underneath the crust to push the magma, or sometimes water and steam, up the crust. Features like volcanoes, geysers and hot springs are formed in these areas

The Different Types Of Volcanoes

A volcano, by geographical definition, is any conical or dome-shaped structure that is formed as a result of magma escaping to the surface of the Earth through an opening which we call a vent. There are various types of volcanoes, ranging from flat shield-shaped ones to tall and steep ones.

Why are there so many types of volcano? There are volcanoes which erupt violently, those which do not erupt with much force, those which are extremely high, those which are shaped like shields, and so many others. There are a few factors affecting the types of volcano formed, and basically, these factors are mainly determined by the type of plate movement taking place at the plate boundaries and the nature of the lava.

Most earthquakes, volcanoes and mountain forming takes place at plate boundaries.

Formation of Volcanoes

Formation of Volcanoes:
Underwater volcanoes erupt a lot at diverging boundaries. Subduction (The driving down below of the thinner denser ocean plate below the thicker continental plate) at ocean trenches also leads to earthquakes as it is heated and softened as it rubs against the other plate. The water is superheated and causes melting and a volcano occurs.

A volcano occurs when an opening in the earth's surface allows magma to escape.