On December 26, 2004, a massive undersea megathrust earthquake, known as the Sumatra-Andaman earthquake, struck off the west coast of northern Sumatra, Indonesia, at 07:58:53 local time (UTC+7). This devastating earthquake, measuring between 9.1 and 9.3 on the moment magnitude scale, was one of the deadliest natural disasters in recorded history. It was caused by a rupture along the fault between the Burma Plate and the Indian Plate, reaching a Mercalli intensity of up to IX in some areas.

The earthquake triggered a colossal tsunami with waves reaching up to 30 meters (100 feet) high, infamously referred to as the Boxing Day Tsunami. This tsunami ravaged communities along the coasts of the Indian Ocean, resulting in an estimated 227,898 deaths across 14 countries. The disaster particularly impacted regions such as Aceh in Indonesia, Sri Lanka, Tamil Nadu in India, and Khao Lak in Thailand, with Banda Aceh reporting the highest number of casualties. It remains the deadliest natural disaster of the 21st century.

This event was the most powerful earthquake ever recorded in Asia and the 21st century, and one of the most powerful in the world since modern seismography began in 1900. The earthquake had an extraordinarily long duration of faulting, lasting between eight and ten minutes. It caused significant vibrations of the planet, measuring up to 10 mm (0.4 in), and even triggered remote earthquakes as far away as Alaska.