History's Deadliest Natural Disaster Killed Millions

"The single-most powerful explosive event ever witnessed" took place somewhere between 1645 BC and 1500 BC, when the volcano Thera erupted on what's now the island of Santorini. LiveScience reports its power has been likened to that of an 1883 eruption in Indonesia that could be heard 3,000 miles away and killed some 40,000 people. No such count is available for the Thera explosion, which is why it doesn't make LiveScience's list of the 11 deadliest natural disasters "for which reasonably accurate death tolls exist." It includes the 2004 Indian Ocean quake and tsunami, which hit Indonesia hardest and killed as many as a quarter of a million people overall. Here are five disasters that didn't strike so recently:

1. 526 Antioch quake: The best estimate comes from John Malalas, a Greek chronicler from the Byzantine city where the quake struck whose writings from the time put the toll at about 250,000. A 2007 paper noted that the temblor's May timing was inopportune as the city's population was swollen with tourists there for Ascension Day, resulting in an elevated toll.
2. 1556 Shaanxi earthquake: As far as earthquakes go, this is pretty much the worst. Believed to have been about a magnitude 8, it is said to have demolished a 621-square-mile region of China's Shaanxi province on Jan. 23 of that year, killing some 830,000 people.
3. 1839 India cyclone: Some 20,000 ships were wiped out by the cyclone and resulting storm surge that struck the port city of Coringa on Nov. 25, but that number pales in comparison to the estimated death toll: 300,000 people.
4. 1920 Haiyuan earthquake: The US Geological Survey believes that this quake that hit central China on Dec. 16 of that year registered as a magnitude 7.8. Landslides were a big contributor to the death toll, which researchers in 2010 estimated as 273,400.
5. 1931 Central China Floods: Pegged by LiveScience as the deadliest of all natural disasters, this one spanned the months of July and August. The estimated ranges of those killed is a huge one, but the number is big regardless: Somewhere between 2 million and 3.7 million were killed when the Yangtze River flooded due to strong rains and melting snow, affecting some 70,000 square miles.

Click for LiveScience's full list. (More lists stories.)