What caused the Indonesian earthquake?

The 2004 Indonesian earthquake was caused by the earth's Indian plate moving underneath the Burma plate, causing a massive release of seismic stress and resulting in faults. This led to earthquakes and tsunamis in 14 Asian countries. It is also known as the Indian Ocean earthquake or the Sumatra earthquake.

The megathrust earthquake and resulting 100-foot tsunamis resulted in 130,000 casualties and had a significant environmental and economic impact, making it one of the worst natural disasters in recorded history. It was first ranked at an 8.8 on the moment magnitude scale and later changed to a 9.0 in 2005.