I don't know...too many theories, make my head hurt. My kitchen-physics suggests a magnetic disturbance, liquifaction, resonance effect.
If I was a betting man my money would be on the one most recent global legendary cataclysmic event known as:
Noah’s Flood!
See www.creationscience.com for more on the hydroplate theory and all that is implied w/ it. Course you also must be willing to realize old age dating methods are highly called into question.