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The 2004 earthquake and tsunami in Banda Aceh, Indonesia, stunned the world. About 23,0000 people died and caused damage as far away as Africa. Less than a year later, an earthquake in Pakistan killed about 80,000 people. Earthquakes are sudden movements in the Earth's crust that occur along faults (chambers/planes of weakness) where one rock mass passes another. When there is gradual and relatively smooth movement along faults, it is called a crack or seismic slip and may go undetected by the casual observer. When friction prevents rocks from sliding easily, stress builds up until it is finally released through a sudden jolt. The point in the fault where the first movement occurs during an earthquake is called the epicenter.

Earthquakes are always mysterious, sudden, violent, come without warning and leave devastated cities and displaced landscapes in their wake. Cities such as Kobe, Japan or Mexico City, built partly on soft ground or loosely consolidated soil, usually suffer great damage from earthquakes. Water-saturated soil can liquefy when shaken. Under such conditions, buildings often sink or collapse like rows of dominoes.