The twon of Ripon, in NE England, has occasionally suffered similar collapses, into natural cavities about 100 feet (I think I was told) further down. In other places, old mines have caused problems.
@Tumbleweed It reminds me of something a friend living not far from London told me, about local road-building breaching a large cavity with a solid rock floor. This happened back in the 1970s I think.
The County Council would not seek or take advice, and simply ordered pouring concrete down it. It took vast quantities of concrete until eventually plugging it - allegedly at the cost of bankrupting three ready-mixed concrete suppliers.
The road-works cutting had breached the roof of a long-abandoned underground stone quarry whose extensive galleries are on a gentle slope. So most of the concrete was wasted by flowing away.
Local cavers had already explored and mapped these old mines, creating a sizeable archive of high-quality knowledge; but being amateur historians without fancy qualifications and even fancier offices, the council planners simply ignored them.
@ArishMell Oh that's terrible!!! I read, several years ago, where a road crew or somebody actually discovered a cave in Mexico, the crystal cave, it's beautiful!!!
