People gather in front of a highrise building on Silom Road yesterday after rushing out in the wake of tremors.

An earthquake measuring 6.1 on the Richter scale yesterday sent tremors from the northernmost provinces down to Bangkok.

Your experience on tremors welcomed

The powerful quake's epicentre was near the border with Burma and Laos in the far North, but the capital's soft foundations were blamed for intensifying the tremors by three or four times.

The earthquake took place at 3.56pm.

"The soft clay is the reason why the tremor was felt in Bangkok even though the earthquake took place 700 kilometres away," Asian Institute of Technology's seismologist Dr Penneung Wanichchai said.

He said the tremors would generally be much more violent on the higher floors of buildings than on the ground.

Many of those who felt the impact in Bangkok were in high-rise tower blocks.

Pennueng described yesterday's incident as "shocking but not dangerous" to Bangkok residents.

However, he warned that if a powerful earthquake occurred closer to Bangkok, the city could face serious consequences.

He said there were two faults in Kanchanaburi, about 200 kilometres away from the capital.

Currently, only buildings in the northern provinces and Kanchana-buri are legally required to be 'quake-proof'.

Mineral Resources Department director general, Apichai Chawa-charoenpan said authorities were now closely monitoring aftershocks from the 6.1-Richter-scale quake.

Chairman of the National Disaster Warning Centre Smith Dharmasaroja said more than 10 aftershocks had followed the powerful quake.

He warned people in provinces in the far North, such as Chiang Rai, Chiang Mai and Mae Hong Son, to be on the alert.

"Landslides may take place," he said.

The Disaster Prevention and Mitigation Department (DPMD) reported that the tiered umbrella of Chom Kitti Pagoda in Chiang Rai's Chiang Saen district collapsed and cracks also appeared on the ancient pagoda because of the quake.

The pagoda is 1,067 years old.

In other parts of Chiang Rai, local people reported their houses shook violently and many items hanging on the walls fell down.

In Chiang Mai's Muang district, tourists at the Doi Suthep Temple also felt the tremor but remained calm. "They showed signs of surprise but nobody panicked," said Wallop Namwongphrom, who was in charge of the temple's PR activities.

The revered temple is popular tourist attraction.

"Nothing fell down and vendors at the temple ran their business as usual," Wallop said, adding the temple's staff were well prepared to deal with emergencies.

In Chiang Mai's Mae Rim district, mini-mart owner Jantima Saengmee said the tremor was so powerful that her shop shook, and stock was thrown off the shelves.

"Some of the customers rushed outside while others clung to the shop's pillars," Jantima said.

The DPMD said tremors were also felt in Nan, Phayao and Phrae but no damage was reported.

In Bangkok, office workers in many high-rise buildings felt the impact and rushed out into the streets. Windows were reported smashed on the top floors of the MBK building opposite Siam Square.

"My head was sort of swirling. I asked my colleagues 'what happened'?" said Yupa, an office worker on the 16th floor of the Maneeya Building in Bangkok's Ploenchit area.

As soon as someone mentioned "earthquake", Yupa and her colleagues rushed from their office.

"I felt the tremors three or four times while we went down the stairs," she said.