GEOPHYSICISTS WERE called in after a Norfolk road collapsed into a 8m deep hole last month.
Ampthill Geophysical Consulting attended the site at Thetford, where the 2m wide fissure opened up.
A spokesman for Norfolk County Council said: 'On 5 January the road collapsed at Fulmerston Road. A water main, gas main, gulley pipes and telephone cables were all severed and we were left with a hole in the middle of a residential road.' A car was caught on the precipice of the crater and had to be removed by crane, but police said no one was injured at the scene.
Nearby residents were evacuated and a local school was used as a relief centre.
Although the cause of the ground movement remains a mystery it appears underlying chalk had been washed away, leaving a cavity. It is also unclear if the hole is a consequence of the ruptured water main or vice versa.
The spokesman said: 'Ampthill Geophysical used radar images to assess the depth of the hole and see if there were more cavities or voids. I believe it found a second hole 10m from the initial one.' Ampthill senior partner Tim Scull said: 'Work is ongoing but we suspect it [is caused by] a fracturing of the chalk.' A mixture of concrete and granular fill plugged and stabilised the hole but the road remained closed as GE went to press.