Bangkok, March 31 -- Thai authorities on March 30 launched an investigation to determine the cause of the collapse of the 30-storey building in Chatuchak district, Bangkok, following the 7.7-magnitude quake that struck Myanmar two days earlier.

It is the only building in Bangkok that collapsed due to the tremor following the earthquake.

An investigation team from the Ministry of Industry has collected samples of construction materials from the site of the collapsed State Audit Office (SAO) building in Chatuchak district, said Pongpol Yodmuangcharoen, Secretary to Industry Minister Akanat Promphan.

The team is focusing on the quality of steel bars used in fortifying concrete polls, beams and foundation structures in particular, as subst...