What is an Earthquake?

An earthquake that struck Indonesia on Wednesday has resulted in the deaths of five people. The 8.6-magnitude quake was felt as far away as south India, a distance of around 3867 kilometres. However, tsunami warnings were not issued due to the waves of the earthquake moving horizontally and not vertically.

Earthquakes are the most common causes of tsunamis due to the disturbance under water. A vast volume of water creates a series of waves that rise up when they reach shallow depths. In 2004 an enormous tsunami following an earthquake killed 230,000 people in 13 different Indian Ocean countries.