The 2003 Bachu earthquake occurred on 24 February at 10:03 local time in the Xinjiang Autonomous Region in northwest China.

It occurs as a result of movement on fault systems that bound the Tien Shan mountain belt.

The Tien Shan is actively evolving, as a result of far-field stresses associated with the collision of India and Eurasia.

According to the moment tensor solution, the earthquake occurred on a thrust fault that dips 6° to the north, and strikes approximately east–west.

Such a gentle dip angle implies that the earthquake may have occurred on or just above the basal detachment of the neighbouring fold-thrust belts.