Earthquake is a natural phenomenon that occurs when two blocks of rock, called plates, suddenly slip past each other. This releases energy that makes the Earth shake and creates seismic waves that travel through the ground. The spot underground where the rocks first break is called the focus or hypocenter. The spot above it on the surface of the Earth is called the epicenter.
Earthquakes can also cause tsunamis and seiches (waves in lakes) that could injure or kill people on shorelines. They can also damage roads and bridges, causing them to close. They can also disrupt water supplies, contaminating drinking and bathing water with debris, sewage or chemicals. This can lead to outbreaks and epidemics of diseases, such as diarrhea, cholera, measles and typhoid fever.
During an earthquake, crouch down in a safe place and hold on. Avoid moving around, as this increases your risk of injury. Remember, most earthquakes only last a few seconds, but the shaking may feel like it’s lasting much longer.
Some signs that an earthquake is coming are small tremors, known as foreshocks; unusual behavior by animals (from toads to chickens); and changes in the level of groundwater or radon gas. These can be caused by shifts in the stress on fault lines, and some are warnings of a more severe earthquake to come.
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