UPDATE: THE head of the mine subsidence board says there is no risk to surrounding properties in the the street where two sink holes have appeared.
In a press conference on Wednesday morning Greg Cole-Clark said the sinkholes were "an unusual" event and analysis was being undertaken.
"We don't have undue concern for any other properties other than those that have been immediately affected," he said.
"We will continue to do a bit more analysis as time passes."
Mr Cole-Clark said the two homeowners affected by the sinkholes would be compensated by the Mine Subsidence Compensation Act for the damage.
However he would not comment on whether there would be any compensation for the diminished value of their homes.
Both affected houses have stunning views of the water.
"We are now in the process of securing the site," Mr Cole-Clark said.
"There are mine workings under the site, they were abandoned about1953.
"At this point in time we assume they're about 25 metres in depth.
"There has been no history of mine subsidence in this area for 60 years or more.
"It is an unusual event."
Mr Cole-Clark said the hole had been made worse by sand flowing into it over time.
"We'll have concrete put into it in the next hour or two then look at supporting the home," he said.
A second sink hole which appeared in a home two doors down from the first damaged home at 5am may have been "cause and effect," Mr Cole-Clark said.
Watch the video of the press conference from CEO of the Mine Subsidence Board, Greg Cole-Clark.
A SECOND sinkhole has opened up in Lambton Parade, Swansea Heads.
It follows dramatic scenes in Lambton Parade last 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 this 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.