Earthquakes involve the powerful movement of rocks in the Earth’s crust. The rapid release of energy creates seismic waves that travel through the earth.
Scientists use the different speeds of seismic waves to locate the epicentre (the point on the surface directly above where the earthquake originated) of earthquakes.
Seismometers are used to measure the magnitude of earthquakes. You are unlikely to feel a magnitude 3 earthquake but a magnitude 6 earthquake could potentially cause large damage.
The damage caused by earthquakes also depends on their depth and fault type.
The earthquake that hit the Tohoku region of Japan on March 11, 2011, had a magnitude of 9.0 and killed over 15000 people.
The destruction caused by the Tohoku earthquake was made much worse by powerful tsunamis that were triggered due to the earthquake’s epicentre being located offshore. More tsunami facts.
The 2004 earthquake that occurred in the Indian Ocean near Sumatra, Indonesia triggered a series of tsunamis that killed over 200000 people in 14 countries.
The February 2011 earthquake in Christchurch, New Zealand followed nearly 6 months after a magnitude 7.1 earthquake shook the region. The earthquake killed 181 people and significantly damaged the central city. The economic damage caused by the earthquake and aftershocks is estimated to be around $15 billion (NZ$).
An earthquake that hit Haiti in January 2010 with a magnitude of 7.0 killed over 200000 people according to Haitian sources.
The most powerful earthquake ever recorded on Earth was in Valdivia, Chile. Occurring in 1960, it had a magnitude of 9.5.
It is important in earthquake prone countries such as Japan to build houses and buildings that react well to earthquakes. Good engineering practises can help stop buildings collapsing under the stress of large earthquakes.