Subsidence affecting nine townhouses at a housing estate in Pathum Thani could have resulted from pile foundations breaking underground due to soft soil, according to an initial investigation by the Engineering Institute of Thailand (EIT) Wednesday.
The EIT team, led by adviser to EIT secretary-general Thanet Weerasiri, inspected the two-storey townhouses in the Rinthong estate of Lam Luk Ka district that have subsided since Monday.
Mr Thanet said Wednesday the estate was constructed on soft soil.
The developer filled some areas with soil, around 20 to 50 metres in depth, before construction started.
Pile foundations that were insufficiently embedded could have led to the buildings collapsing, he said.
Residents in the nine townhouses of the housing estate were forced to flee their homes on Monday when cracks attributed to soil subsidence appeared in their houses, leaving them uninhabitable.
Mr Thanet said more piles could be driven into the ground to maintain the houses but it would be costly.
Meanwhile, also in Pathum Thani, two people and a four-year-old girl fled their homes after their houses completely subsided in Khlong Luang district on Tuesday night. Yupin Saengngiew, 62, said she and her nephew managed to escape from their home after hearing a loud noise.
However, Ms Yupin found her neighbour, Srisak Sripatchanon, was still inside his house.
Mr Srisak, who received an electric shock, was later rescued by residents.
Pachai Poriyanon, the Khlong Luang district chief, said authorities have been unable to determine the cause of the subsidence.
However, the houses were reportedly built on land which earlier was under water. The land may not have been properly reclaimed for building work.