Earthquakes are perhaps one of natures most breathtaking, yet deadly and destructive wonders.

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         The causes, distribution and effects of earthquakes

        

Earthquakes are perhaps one of natures most breathtaking, yet deadly and destructive wonders that remain untamed by modern day man and his ever advancing technological and scientific evolution. Deaths, fires and economic ruin are all associated with this massive battle with nature.

German meteorologist Alfred Wegener discovered in 1912 the earth’s continents in fact fit together like pieces in a giant jigsaw puzzle, and 200 million years ago there would have existed a single land mass, much different to the familiar face of the earth today (diagram 1) . Significant scientific and geological research and developments made since have not only confirmed this, but led to the conclusion that our earth is not as stagnant as once assumed. In fact, on the contrary, it is dynamic and always changing and over millions of years the once united landscape has fragmented and moved apart to create the world as it is now commonly known. The explanation for these amazing shifts of enormous continental land masses lies right at the heart of the earth, hundreds of miles below the surface at the core.

The earth is composed ultimately of three layers; from the outer crust of surface as it is commonly known, the mantle below the surface right through to the hot molten centre, known as the core, where rocks burn at temperatures upwards of  7000 ºC (diagram 2) . The crust is a thin hard layer of rock, which is split into 15 parts known as crustal plates and these float around on the mantle (diagram 3). The mantle is a hotter, denser and ultimately softer layer than the surface and this allows the crustal plates some movement. The core however is the catalyst for these movements and all there resultant problems. Located right at the centre of the earth this vast mass of churning, burning molten rock is always moving and sending currents of burning rock into the mantle region which upon collision with the bottom surface of the earth’s crust and plates wreaks havoc with the planets habitat .

The results are earthquakes; violent shaking of the ground that allows a release of pressure at these plate boundaries where the stress has built up due to currents beneath the crust. Movement of the plates takes place in one of three ways: spreading where two plates are moving away from each other such as the Mid-Atlantic Ridge, transform faults where the two plates scrape against each other whilst moving laterally in opposite directions and finally subduction zones where two plates move together with one eventually subsiding underneath the other and being forced into the mantle where it melts.

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Many earthquakes occur daily worldwide, even here in Scotland, they are so small however they pass unnoticed. These tremors are the result of developing fault lines which are much smaller fractures to the earths crust and in most cases such as the Great Highland Fault have no effect on everyday life and many exist worldwide. Fault lines do however have the potential for major damage as famously documented at the San Andreas Fault which is an earthquake hotspot, however this is a more complex fault with pressure being applied in three ways, making it a time bomb for disaster.

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