Worawut Tantivanch, an expert at the department, said the two faults - which run through Surat Thani, Phang Nga and Ranong - are linked to the major fault that caused the earthquake that triggered the devastating tsunami two years ago.

He said that last year there were at least 10 low-magnitude quakes caused by the Marui fault. Regarding the Ranong fault, he said the department was convinced that it had triggered a tremor that shook Surat Thani two months ago.

"The study of the faults will help us evaluate the size of the faults and whether they could generate a major earthquake," he said.

Since the tsunami, earthquakes have been more commonly reported. The department has informed the public that earthquakes unfortunately are a normal phenomenon in some countries, as seen by those that have occurred in Japan.

Apichai Chawacharoenphan, director-general of the department, said that last year there were 16 medium-magnitude earthquakes that had their epicentres in Thailand and were felt in neighbouring countries. These mostly occurred in the north and south of Thailand.

For example, on September 28 an earthquake measuring 4.8 on the Richter scale, with its epicentre in Burma, was felt in many districts of Prachuap Khiri Khan.

Another quake also measuring 4.8 on the Richter scale with its epicentre in Chiang Mai's Mae Rim district was caused by the Mae Tha fault.

Apichai advised the public not to be alarmed, as most earthquakes affecting Thailand were relatively minor. People would only feel some shaking, with no severe risk to lives or property.

Frequent minor tremors help reduce the energy generated by fault movements and lessen the risk of high-magnitude quakes.