Authorities said the capital was mildly rocked by tremors from a 6.1 magnitude earthquake on the northern border with Laos.

"Shortly before 4pm while I was sitting in my office on the 10th floor, I felt the building rock twice and the curtains flapped like they were being blown by the wind. Somebody shouted, 'earthquake'. We all ran out of the building using the stairs, not the elevator," Tai, an office worker in the Ratchada-phisek area, told The Nation in a shaky voice.

"We waited downstairs for about 30 minutes and went back to work, as if nothing had happened," she said.

The Nation and its website were flooded with calls and hits from people who felt tremors after the quake.

One citizen reporter, Joel Barlow, wrote about his experience.

"It started slowly - I was reading while lying on my bed and it shook. Then it became violent and a roof extension between our house and carport fell down. A picture continued swinging several minutes ... For a second or two it was very scary, and the whole thing seemed to last more than just a few seconds, quite long enough to really wonder what was happening, and know, but not long enough to go stand in a doorway or anything."

Nation business reporter Nitida Asawanipont felt the undulations in the Amarin Building on Ploenchit Road. "The chandeliers were shaking and I felt dizzy," she said.

Bill Reynolds, from Chiang Mai, was nearer to the epicentre.

"At about 4:45pm I experienced a swaying sensation as I sat watching television. It lasted in the vicinity of 10 to 15 seconds. I realised that I was feeling the effects of an earth tremor but not the those of a nearby earthquake."

A worker in the 23-storey Olympia Building on Ratchada-phisek in Bangkok said the swaying motion made her feel woozy.

"Before the earthquake I took something to kill my headache. At first I thought it was a side effect of the medicine as I saw the curtains swishing for about a minute. I called the supervisors in charge of the building to see what had happened. When they mentioned the earthquake, I logged in to the website of the Geological Department to check," the worker, who asked not to be named, said.

Neelanut Noothong, an office worker on the 17th floor of Shin Tower III, was also bamboozled by the quake.

"At first, around 4.10pm, I did not imagine there was an earthquake when I felt giddy. Then somebody said it was a quake and told us to go home. Many people panicked, running out of the building using the stairs, not the elevator. We stayed downstairs for about 20 minutes. After seeing that nothing had happened, we went back to work. But later, the company allowed us to go home for safety reasons."

A woman from the 16th floor of the Rachapak Building in Din Daeng said she felt dizzy for a few minutes. "Other staff felt the same and we realised it was an earthquake. I rushed to pick up my things before joining the others and running down the building. When we reached the ground, many people from nearby buildings were already there. We were told to go home."