An earthquake is defined as a vibration, which can sometimes occur as a violent movement of the earth, that follows an energy release in the Earth's crust.
Earthquakes can occur virtually anywhere.
Although they cannot be prevented, damage, destruction and loss of life can be reduced with sufficient preparation. Earthquakes are commonly measured by the Richter magnitude scale, which measures the size of earthquakes. On the Richter measurement, the size, or magnitude of an earthquake, is usually expressed in whole numbers and decimal fractions. Each whole number increase in magnitude represents a release of about 31 times more energy than the preceding whole number value, or a tenfold increase in amplitude. Generally, earthquakes that measure 2.0 or less on the richter scales are called microearthquakes and are usually not felt.