The Influenza epidemic of 1918-1919 killed over 25 million people worldwide. It remains America's deadliest disease outbreak.

Cholera epidemics have occurred all over the world and the disease is still active in some tropical regions.

After San Francisco was rocked by one of the most powerful earthquakes ever to hit North America, fires burned out of control for four days and nearly finished off the city. Most of the means to fight the fires had been destroyed by the 7.8 magnitude quake.

After San Francisco was rocked by one of the most powerful earthquakes ever to hit North America, fires burned out of control for four days and nearly finished off the city. Most of the means to fight the fires had been destroyed by the 7.8 magnitude quake.

After San Francisco was rocked by one of the most powerful earthquakes ever to hit North America, fires burned out of control for four days and nearly finished off the city. Most of the means to fight the fires had been destroyed by the 7.8 magnitude quake.

On July 28, 1945, a B-25 bomber, lost in the fog, smashed into the 78th floor of the Empire State Building. 13 people died.

On December 5, 1945, five planes on patrol and the search plane sent to look for them all disappeared in the Bermuda Triangle.

The Fujita Scale is used to rank tornadoes, from F0 to F5, based on the degree of damage they caused. An F5 tornado has winds up to 318 mph!

The VEI Scale, or Volcanic Explosivity Index, is the measure of a volcano's eruption. A VEI of 8 is called mega-colossal, but no need to worry. An eruption that big only happens every 10,000 years or so.