On December 26, 2004, a magnitude 9.1 earthquake struck the seafloor about 100 miles off the coast of Sumatra, Indonesia. The quake itself was not unusually powerful, but it triggered a series of devastating tsunami waves that smashed into coastal communities on Sumatra and the islands of Java and Sri Lanka.
The tsunami waves were up to 100 feet (30 meters) high in some places, and they swept away homes, cars, and entire villages. More than 230,000 people were killed …