A tsunami is a series of giant waves usually caused by earthquakes or volcanic eruptions on the seafloor. When the wave nears the shore, it slows down and quickly increases in height to over 30 meters before crashing onto the coast. The 2004 Indian Ocean tsunami was caused by a 9.1 magnitude earthquake and resulted in over 280,000 deaths, 650,000 serious injuries, and 2 million people being made homeless across several countries in Southeast Asia and Africa. The devastating effects prompted responses including relief appeals and the establishment of early warning systems in the affected regions.