sinkholes are appearing at five times their normal rate

On Saturday, a huge sinkhole opened up at the side of a house in Hemel Hempstead, Hertfordshire. Swallowing up half of the front lawn, it was 35ft wide and 20ft deep.

Last week, a hole as deep as a double-decker bus is high suddenly opened up in the back-garden of a house in South-East London, almost swallowing a child’s trampoline as the ground collapsed without warning.

Had the poor owner’s daughter been rushing out to play on the trampoline, she could have very easily have been seriously injured or even killed.

Two weeks ago, there was a similarly narrow escape for a family living in High Wycombe, when, overnight, a deep hole appeared  without warning in the driveway just next to the house.

This time the adult daughter’s car did end up buried at the bottom of the hole, thankfully, while there was no one in it. 

And in Kent last week, motorists hoping to use the M2 were left fuming by the motorway’s temporary closure, after a substantial hole — 15ft deep — suddenly appeared in the central reservation. Again, no one was hurt but had the hole opened up just a few yards away, it is obvious what a different story it could so easily have been.

All of these holes are what the public call sinkholes and now, after weeks of heavy rain, they seem to be appearing with ever greater regularity. Hard statistics are difficult to find — not least because sinkholes that appear on farmland often go unreported — but having studied them for 35 years, I’d estimate that sinkholes are currently appearing at four-to-five times their normal rate.

With more heavy rain forecast, I’d be surprised if we’ve seen the last sudden sinkhole of this winter.

Even when the rain does stop and warmer weather returns, for reasons that I’ll come to, there could be a second spate of them.

Strictly speaking — and as I work for the British Geological Survey I do need to be strict about these things — not all the big holes that have been appearing are sinkholes. Technically, a sinkhole is a hole that opens up when the surface layers collapse into a naturally made cavity. When the surface layers collapse into a cavity made by man  — and at least two of the recent holes are in areas where mining has been carried out in the past — then it should be called a dene or crown hole. TRUNews