The magnitude 9.0 that hit Banda Aceh, Indonesia and resulting Indian Ocean tsunami on December 26, 2004 was the deadliest earthquake since Jan. 23, 1556 when a magnitude 8 earthquake killed an estimated 830,000 people in Shansi, China. The U.S. Geological Survey estimates that the tally from the 2004 disaster as more than 275,950. More from the USGS.