What is the name of the fault that ruptured in the 2004 Indian Ocean earthquake?

The fault that ruptured in the 2004 Indian Ocean earthquake was the Sunda megathrust. It forms the subduction boundary where the Indo-Australian Plate moves beneath the overriding Burma Plate, part of the broader Eurasian plate system.

On 26 December 2004, a section of this fault ruptured off northern Sumatra and extended northward toward the Andaman and Nicobar Islands. The rupture lasted several minutes and displaced the seafloor, pushing an enormous volume of seawater upward and generating the Indian Ocean tsunami.

The Sunda megathrust stretches for about 5,500 kilometres from Myanmar past Sumatra and Java toward the region near Australia. The 2004 rupture was one of the largest ever instrumentally recorded and caused approximately 228,000 deaths across countries bordering the Indian Ocean.