20 years ago today, one of the costliest natural disasters to ever strike the U.S. erupted. A 6.7 magnitude quake rocked southern California. In just 10 seconds time, bridges collapsed, roads buckled, walls fell, and buildings crumbled leaving more than 20 billion dollars in damage. The shaking was felt from central California's farmlands south to San Diego and eastward to Las Vegas and Flagstaff Arizona. All told, 72 people were killed, more than 9,000 injured. 82,000 buildings were damaged or destroyed. Afterward, many called this tremor not only a wake up call for Californians living in one of the most seismically active areas in the world, but a blessing because it occurred in the very early hours of the morning when traffic was at a minimum. It is believed that IF this same earthquake had happened just a few hours later, the death toll could have been "catastrophic." This was the last major earthquake to strike a heavily populated area in the U.S. and it's only a matter of time before the next one hits. In all likelihood, it will happen in California in our lifetime… of course you probably know it as "the big one."