Earthquakes are currently among the world's deadliest Natural disasters. From 2004 to 2014 around 800,000 earthquakes have rocked the earth, some causing minor damage while some causing a change in the landscape. Earthquake are caused by the movements of the earth's tectonic plates. Seismic activity is concentrated along fault lines, areas of fracture in the earth's crust generally near tectonic plate boundaries. Tectonic plates are always moving. When they collide, one is pushed slowly beneath the other. The resulting friction creates energy along the fault lines which eventually becomes so unstable that it ruptures sending out shock waves. This energy release is felt and known as an earthquake. Most movement goes completely unnoticed but occasionaly an enormous earthquake strikes and completely brainwashes us. The point underground at which the movement occurs is called the focus.
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The point underground at which the movement occurs is called the focus.
The spot at which the shock waves first reach the surface is called the epicentre. A seismograph measures the duration, magnitude and the direction of an earthquake. Seismographs are designed to detect the slightest earth vibrations and move the instrument. |
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