Tsunamis are often triggered by volcanic eruptions, earthquakes, landslides, or meteorites—and the waves can spread out thousands of miles. | National Geographic

🌊 The Deadliest Tsunami in Recorded History On December 26, 2004, the world witnessed the most deadly tsunami ever documented. A massive 9.1–9.3 magnitude undersea earthquake struck off the coast of Sumatra, Indonesia. It was so powerful it shifted the Earth’s axis and created a series of tsunami waves that spread across the Indian Ocean at the speed of a jet plane. Within hours, coastlines in 14 countries were hit — including Indonesia, Sri Lanka, India, Thailand, and the Maldives. The Impact