This resource is an abstract. This study tracks the movement of the rupture that caused the December 26, 2004 Indian Ocean tsunami by comparing recordings of sound waves from five sensors located around the Indian Ocean. The data were used to triangulate the location of sound wave source. Results indicated that the rupture first moved northwest at 2.4 kilometers per second along the Sunda trench then slowed to 1.5 kilometers per second around 600 kilometers from the earthquake's epicenter. The author indicates that the slower speed of the rupture was unusual for an earthquake caused by a rupture close to the surface.