Cover-collapse sinkholes can open up suddenly.

Detailed Description
Cover-collapse sinkholes
Cover-collapse sinkholes may develop abruptly (over a period of hours) and cause catastrophic damages. They occur where the covering sediments contain a significant amount of clay. Over time, surface drainage, erosion, and deposition of sinkhole into a shallower bowl-shaped depression.
Details
Image Dimensions: 967 x 290
Date Taken:
Location Taken: US