They can turn bright blue skies dark as the night. They can, in an instant, make entire cities disappear. They can crush the human spirit with unflinching indifference. They are natural disasters, unforgiving forces of nature that bend steel, smash concrete, and rip human bodies to shreds. Rampaging floods, roiling oceans, boiling mountains of lava. The beauty of nature can turn on a dime, creating some of the most horrific events ever recorded in human history. Names like Vesuvius, Galveston, Johnstown are tragic reminders of an unbridled power unleashed without warning, destructive forces that can catch even the most wary souls off guard, wiping them from the face of the Earth.