Families fled their homes as 25 houses collapsed into a canal as the bank crumbled away in Bang Phli district on Thursday night.
No casualties were reported.
Police, district officials and rescue workers were called to the canal-side community at Soi Srisamphan in tambon Bang Phla about 9pm, Pol Lt Col Sitphong Panthaisong, investigation chief at Bang Phli police station, said.
They were confronted with a row of collapsed houses, which had tumbled into Khlong Bang Hia.
Residents had earlier begun fleeing their homes, removing what belongings they could. There were no injuries, police said.
Emergency services were mobilised to help the distraught residents as police cordoned off the area. (continues below)
Residents said an earth embankment along the canal and a flood embankment along a nearby 400-rai pond began to subside on Monday evening.
A subcontractor began using a backhoe to repair the earth embankment. However, soil was very soft and land continued to gradually subside.
The subsidence became very severe on Thursday night, residents said.
The earth embankment broke and water from the canal flooded into the nearby pond, which was about 100 metres deep.
The canal soon ran dry and the bank began to crumble, pulling down houses built along the canal-side. Twenty-five houses collapsed.
Bang Phli district chief Somsak Kaewsena declared the community a disaster zone, releasing assistance funds. All affected residents were evacuated to a temporary shelter at Wat Tamru.
Chanin Rungruang, former chairman of Bang Phla tambon administration organisation, said complaints had earlier been lodged about soil being dug out of the pond and carted away for sale.
A local official said the owner of the pond had earlier sought permission to excavate and sell the dirt, Mr Chanin said.
(Photo: Sutthiwit Chayutworakan)