The department issued a statement after news widely shared on social media that the two tsunami buoys had stopped feeding information to the National Data Buoy Centre website run by the National Oceanic and Atmospheric Administration (NOAA) of the United States.
The department’s statement said Thailand had deployed one tsunami-detection buoy, called "Station 23401", in the Indian Ocean, which is 965 kilometres west of Phuket island.
The second tsunami-detection buoy -- "Station 23461" -- was deployed in the Andaman Sea about 340 kilometres off the coast.
The department said the two buoys had been receiving proper maintenance every two years in accordance with the NOAA standard, but on Octobr 22, Station 23401 was swept off the deployed spot and stopped sending out signals.
The buoy was later recovered. The manufacturer will install a new buoy to replace it within November, the statement said.
The department said it had noticed that Station 23461 in the Andaman Sea was sending out irregular data on May 21 and the NOAA stopped its feeding of data to the National Data Buoy Centre website pending an investigation.
The department said it had checked the data fed by the Andaman buoy and found it had started sending correct information about the changes in sea level so the department has turned its data on on the website.
The department insisted that it had been monitoring the tsunami in accordance with the standard operating procedure and has been using overseas data for analysing tsunami risks.
As a result, it is confident it will be able to warn the public of any tsunami in the future, in time for evacuations, the statement said.