An undersea earthquake off the coast of Indonesia in 2004 triggered a devastating tsunami across the Indian Ocean. The earthquake, caused by tectonic plate subduction, generated a massive displacement of water that produced 30-foot high waves. Over 250,000 people across 14 countries were killed, with over 130,000 deaths in Indonesia alone. The tsunami destroyed coastal infrastructure and displaced millions of people, while secondary impacts included disease outbreaks and loss of livelihoods. Major humanitarian aid and long-term reconstruction efforts were required.