A second sinkhole has opened up in Lambton Parade, Swansea on the state's central coast.
It follows dramatic scenes in Lambton Parade on Tuesday night when a couple returned home to find their three-storey home sliding into a large sinkhole.
The second, smaller sinkhole opened up in the front garden of a property two doors down.
The Mine Subsidence Board is assessing the new hole on Wednesday morning, which is about two metres wide.
It is also checking the stability and structural integrity of surrounding homes.
The first sinkhole is about 20 metres and deep as 10 metres above a 20 metre vertical furnace shaft.
The area underneath the neighbourhood was once part of the Swansea Pit, a coal mine abandoned in the 1950s.
Police said it was unknown how stable the structure was or whether the hole would develop overnight, causing further damage.
But mine subsidence board officers said they believed the house, built in the 1990s and one of the newest in the street, could be repaired and salvaged.
It was also unclear whether the hole appeared gradually or all at once, but police had not spoken to anyone who had seen or heard it developing.
Nearby residents were able to get a close look at the hole before police arrived, snapping photographs showing the cavity which nearly swallowed up a spare bedroom and an outdoor furniture set.
The picturesque section of Lambton Parade, which overlooks the ocean and entrance to the Swansea channel, was once home to the Swansea Pit.
The mine was abandoned in 1953 and dozens of expensive homes have since been built above.
Mine Subsidence Board officers believe the sinkhole appeared above an old furnace shaft.