The Disaster Center-- Nov. 5, 2011 - 10:28 AM EDT - During the last decade earthquakes killed 780,000 people, making them the worst cause for death by natural disaster, according to a study published in The Lancet. "The reported ratios of death-to-injury vary, but across many studies seems to be about 1-to-3," which makes earthquakes the number one cause of injury by natural disaster..