Geography Tectonics

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  • Created by: Meghna
  • Created on: 19-01-13 17:57

The distribution of Volcanoes and Earthquakes

There are 13 tectonic plates, but 7 major ones. Volcanoes and earthquakes occur at the tectonic plate boundaries, in-between two plates.  Volcanoes occur in the Pacific Ocean and are called the Pacific Ring of Fire. Volcanoes are found at both land and sea and there are no volcanoes in Australia.

Why do they occur where they do?

The gaps between plate boundaries are widened or pushed together by convection currents in the mantle. Depending on the movement of the tectonic plates, these plate boundaries can form volcanoes, earthquakes, trenches and Mountains. The changing position of the plates is called continental drift.

What happens at a convergent plate boundary?

Convergent plates are plates that move towards each other. Two continental plates move towards each other and buckle to form Fold Mountains like the Himalayas. An oceanic plate and a Continental plate move towards each other and the oceanic plate, which is the densest is subducted under the continental plate. This causes intense heat, pressure and friction underneath the continental plate so a cone volcano is formed and erupts, such as in Montserrat. Also, the movement of the subduction can cause earthquakes. For when both plates are oceanic, the older one is subducted, forming an island arch.

What happens at a divergent plate boundary ?

Divergent plate boundaries are tectonic plates that move apart from each other. When this happens in the ocean, magma seeps through the gap created without force, cools down to ford shield volcanoes such as in Iceland. It also constructs new crusts.

What happens at a conservative plate boundary?

At a conservative plate boundary, two plates try to slide past each other. The pressure is built and suddenly released at the focus and shock waves travel at the epicentre at the surface and cause an earthquake.

What is a hotspot

Hot spots are areas of immense pressure and heat in the mantle underneath the crust that burst to form volcanic islands in the ocean. Gradually, a chain of islands such as Hawaii is formed, as the crust moves over the stationary hotspot.

Why do people stay near earthquake prone places?

People who live in Japan, which is a HIC, has made all of their buildings earthquake proof buildings. This can be done by putting reinforced steel and rubber foundations to absorb the harsh shockwaves to make the building sway instead of jolt. Thus means that they are safer. There is also a social reason- many people do not want to leave their friends, family and work, as well as thinking that a large earthquake is unlikely to happen.  There is a great tourism opportunity near earthquake hot spots, so many people find work and are employed to tour tourists around.

Why do people stay near volcanic areas?

There is also a social reason- many people do not want to leave their friends, family and work, as well as thinking that a eruption is unlikely to happen.  There is


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