According to Wikipedia, these are the 10 deadliest natural disasters in recorded history:
1. Yangtze River Flood (China, 1931) ~4 million killed
2. Yangtze River Flood (China, 1887) ~ 2 million killed
3. Shaanxi Earthquake (China, 1556) ~830,000
4. Hurricane Bhola (Bangeladesh, 1970) ~500,000
5. Hurricane (India, 1839) ~350,000
6. Indian Ocean Tsunami (Indonesia etc, 2004) ~283,000
List of natural disasters by death toll - Wikipedia, the free encyclopedia