This story was told to me by a friend, so while I can't account for the accuracy, it is interesting nonetheless.
My friends father-in-law & a friend were fishing Big Bear Lake in the San Bernardino Mountains the morning of June 28th, 1992. That date is significant because a little after 8:00 am, there was a 6.5 earthquake centered at the lake. The two fisherman were near the middle of the lake when they saw the trees shaking, dust & dirt flying off of them. The guessed it was an earthquake and about 30 seconds later, they saw a game warden boat fly past them at full speed, headed away from the dam. The father-in-law happen to glance down at his depth-finder and noticed that it read 45 feet, when just a minute prior they had been in 60 feet of water. He now focused on the depth-finder and was amazed to see the depth quickly changing. 40 feet, 35 feet, 30 feet. He suddenly thought "Oh crap, the dam broke & the lake is draining". He yelled to his buddy to start the outboard (pull start) as the depth-finder continued to drop 20 feet, 15 feet, 10 feet. In the panic, they can't get the outboard started, so both anglers just grab hold of the sides of the boat, bracing for impact. As the depth-finder reached 0 feet, all the water around the lake began bubbling. What had happened wasn't that the dam broke, rather the earthquake had shook loose all of the sediment & methane from the bottom of the lake & the depth-finder misread the rising bubbles as the bottom.
The two fishermen returned to the dock, presumably to get a change of underwear...