Rattle and shake
It seems there is a report of an earthquake almost every day. For scientists who study earthquakes, this is not a surprise. The land that we build our houses on is always moving. It is moving so slowly, we only notice it when there is an earthquake.
An earthquake is a sudden release of energy. This usually happens because the surface of the earth is made up of moving plates. The movement of two plates pushing against each other created the world's tallest mountains - the Himalayas. When two plates next to each other are moving in different directions, pressure builds up. At some point, that pressure will be released in a violent shaking of the ground.
The facts
Earthquakes are measured by the Richter scale. The scale usually goes from 0 to 10. There is no record of an earthquake over 10. It would be classed as 'epic'. An earthquake from 3 to 3.9 is 'minor' - people can feel it, but it usually causes no damage. At 5, earthquakes start to damage buildings. Five to 6 on the scale is classed as 'moderate'. The recent earthquake in Chile was 8.8. This is classed as 'great'. The biggest-ever recorded earthquake was also in Chile. In 1960, the South American country was struck by an earthquake that measured 9.5. The 'epicentre' is the place on the surface where the earthquake happens. Quakes can also take place underground.
The threat to Hong Kong
