In 1556 a earthquake in Shaanxi, China, kills an estimated 830,000 people. The earthquake also triggered landslides, which contributed to the massive death toll. This disaster is still considered the deadliest of all time.
Even if the number of deaths caused by the Shaanxi earthquake has been overestimated slightly, it would still rank as the worst disaster in history by a considerable margin. The earthquake and tsunami in Indonesia in 2004 is generally considered the second deadliest disaster in history.