Officials on Monday gave assurances that two dams withstood an earthquake and two aftershocks with 1.6-4.9-magnitudes in Kanchanaburi from Sunday night to Monday morning, saying the impacts were far below the limit of their durability. Some cracks in walls were reported at local hospitals.
The Earthquake Observation Division of the Meteorological Department reported that the earthquake with magnitude 4.9 on the Richter scale happened at 10.39pm on Sunday, with its epicentre two kilometres underground in Si Sawat district.
Two aftershocks were detected, one with 1.6 magnitude two kilometres underground at 12.01am, and another of 3.0 magnitude 10 kilometres underground at 5.02am on Monday.
The Department of Mineral Resources stated that the earthquake resulted from the movement of the Si Sawad fault line, which stretches through Tak, Uthai Thani, Kanchanaburi and Suphan Buri provinces.
The quake and the aftershocks had no impact on Srinagarind and Vajiralongkorn dams in Kanchanaburi, the department said, because they caused a peak ground acceleration of 0.01-0.02g. The dams were designed for a much higher peak ground acceleration of 0.1g. The two rockfill dams were 55-60 kilometres from the epicentre.
The Srinagarind dam has a capacity of 17.74 billion cubic metres and stands in the Kwai Yai River in tambon Tha Kradan of Si Sawat district. The Vajiralongkorn dam has a capacity of 8.86 billion cubic metres and stands in the Kwai Noi River in tambon Tha Khanoon of Thong Pha Phum district.
The area of the Sunday earthquake was previously struck with a 5.3-magnitude quake on April 15, 1983, followed by temblors of 5.2 and 5.9 magnitude on April 22 of the same year. The quake on Sunday night was felt by people in Kanchanaburi, Suphan Buri, Kamphaeng Phet, Nakhon Pathom, Chai Nat, Ratchaburi, Tak, Nonthaburi and Bangkok, the department said.
Officials were looking for damage to buildings in the provinces. Health officials in Kanchanaburi said several walls were slightly cracked at Tha Kradan and Suksiri Sisawad hospitals in Si Sawat district, but the facilities were not evacuated. There was no structural damage, they said.