Natural Disaster - Earthquakes

Earthquakes

An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. At the Earth's surface, earthquakes manifest themselves by vibration, shaking and sometimes displacement of the ground. The vibrations may vary in magnitude. Earthquakes are caused mostly by slippage within geological faults, but also by other events such as volcanic activity, landslides, mine blasts, and nuclear tests. The underground point of origin of the earthquake is called the focus. The point directly above the focus on the surface is called the epicenter. Earthquakes by themselves rarely kill people or wildlife. It is usually the secondary events that they trigger, such as building collapse, fires, tsunamis (seismic sea waves) and volcanoes, that are actually the human disaster. Many of these could possibly be avoided by better construction, safety systems, early warning and evacuation planning.

Some of the most significant earthquakes in recent times include: The 2004 Indian Ocean earthquake, the third largest earthquake recorded in history,registering a moment magnitude of 9.1-9.3. The huge tsunamis triggered by this earthquake killed at least 229,000 people.

• The 2011 Tōhoku earthquake and tsunami registered a moment magnitude of 9.0. The death toll from the earthquake and tsunami is over 13,000, and over 12,000 people are still missing.
• The 8.8 magnitude February 27, 2010 Chile earthquake and tsunami cost 525 lives.
• The 7.9 magnitude May 12, 2008 Sichuan earthquake in Sichuan Province, China. Death toll at over 61,150 as of May 27, 2008.
• The 7.7 magnitude July 2006 Java earthquake, which also triggered tsunamis.
• The 7.6-7.7 magnitude 2005 Kashmir earthquake, which killed 75,000 in Pakistan.