Japan's giant sinkhole starts sinking again after being repaired in two days

Engineers impressed the world with speed of their job

A giant sinkhole in Japan that was apparently fixed within two days - in a repair that impressed the world - has been closed off once more after the ground began sinking again.

The enormous chasm, 15 metres deep and 30 metres wide, ripped apart the Fukuoka city road but was repaired within 48 hours after a mammoth engineering effort.

However, on Saturday, workmen observed 30 square metres of the road had sunk by around seven centimetres, forcing police to close it overnight.

No damage was caused by the shifting ground and Hakata Street was later reopened.

It later emerged that engineers expected the repaired road to move a small amount following the repair, but this was not publicised by city officials.

The movement was caused as filler material - mostly soil, cement and sand - used to plug the sinkhole began to compress underground. Workers used 7,000 cubic metres of debris to fill the hole and anticipated it would take some time to settle.

The city mayor, Soichiro Takashima, issued an apology on Facebook.

“If you have a little bit of anxiety, you'll have to stop and make sure that you're safe,” he said. “I am sorry to have troubled you.”

The initial sinkhole was blamed on the construction of a nearby subway.

Part of the reason for the fast repair was that sewage water was filling up and threatening to fill the street and buildings were threatened by the hole.