Earthquakes are caused by the movement of tectonic plates. They occur most frequently along plate boundaries. The magnitude of an earthquake is measured on the Richter scale, with higher magnitudes indicating more intense shaking. Earthquakes endanger human lives and cause extensive damage to structures and infrastructure. They disrupt vital systems and can damage economies. Haiti's 2010 earthquake which killed over 250,000 people and left 1.2 million homeless is a prime example of the devastating human and economic impacts of a major seismic event. Proper building codes and preparedness measures can help mitigate earthquake hazards.