On 26 December 2004, a magnitude 9.1 megathrust earthquake ruptured off the west coast of northern Sumatra, along the boundary between the India and Burma plates. The fault slipped over a length of roughly 1,300 kilometres, making it one of the longest ruptures ever documented and the shaking lasted for several minutes. It was among the three most powerful earthquakes recorded since modern instruments existed.
The sudden vertical displacement of the seafloor launched a series of tsunami waves across the entire Indian Ocean. The waves struck coastlines in Indonesia, Sri Lanka, India, Thailand and as far away as East Africa, catching millions of people with no warning system in place. Around 228,000 people were killed across fourteen countries, making it one of the deadliest natural disasters in recorded history.
The Indonesian province of Aceh, closest to the epicentre, suffered the greatest loss of life, with entire coastal communities obliterated. The catastrophe exposed the total absence of a tsunami warning network in the Indian Ocean and led directly to the creation of one. It also triggered one of the largest humanitarian relief efforts ever mounted.