Since the 6.3-magnitude earthquake hit Chiang Rai's Phan district on May 5, a series of aftershocks have been detected by the department.
The aftershocks are common and caused by plate movement, said Suwit Kosuwan, director of Active Fault Research Division.
He explained that a large number of shakes detected after the 6.3-magnitude earthquake is normal when an area has experienced a large-scale earthquake.
People will probably feel a series of light shakes until next month. After that, the situation should return to normal.
But aftershocks less than magnitude 3 on the Richter scale will continue for the next five months.
According to the department, more than 1,000 aftershocks were detected after May 5. However, only 169 were felt by people.
People can only feel it if it is higher than magnitude 3 on the Richter scale.
“Please do not panic. We have found nothing unusual with this earthquake,'' he said.
"At the 6.3-magnitude level, a long series of aftershocks is normal,” he said, adding that the aftershocks are a way to rebalance the fault line after a big movement in the earth's plates.
The department said the magnitude 5 shake in Mae Lao district on Monday was only an aftershock.
People living in the North, especially in Chiang Rai province continue to experience minor shakes every day, and some can’t sleep at home due to the fear of another earthquake.
The epicentre of the 6.3-magnitude quake was previously reported to be from Phayao fault line in Chiang Rai's Phan district.
But the latest information showed the epicentre was actually detected in Mae Lao.
Meanwhile, Penneung Warnitchai of the Asian Institute of Technology, who is an expert on earthquakes, said the 6.3-magnitude earthquake wasn't the highest recorded in Thailand.
In 1935, a 6.5-magnitude earthquake hit Nan province.
“Strong earthquakes are not uncommon for Thailand. We should know there are other fault lines in the North that might generate an earthquake between 6.6 and 6.8 on the Richter scale,” he said.
“But the chance is slim, as the country is not located in an earthquake zone. It would be unlikely to happen, but it can still happen."
Mr Penneung said most people focus on the earthquakes along the fault line approved by the Department of Mineral Resources, but there are many “blind” fault lines under the earth, which could produce a 6.5-quake on the Richter scale.
Unfortunately, those blind fault lines are everywhere in the North and can’t be detected.
But the fact is that they are still active and could cause just as much damage as the main fault lines, he said.
Meanwhile, Public health chief for Chiang Rai, Dr Chamnan Hansuttivejkul, and a team of psychiatrists paid a visit to quake victims in Mae Lao district and found several suffering from psychological illnesses, mostly from depression due to lack of sleep.
Office of the Basic Education Commission (Obec) secretary-general Apichart Jeerawuth said a total of 61 schools were damaged by the quake.
A budget of 500 million baht is expected to be allocated to cover the repairs and rebuilding.
HRH Princess Maha Chakri Sirindhorn expressed her concern over the students' health in the high heat.
The Princess suggested Obec build a temporary shelter with a high ceiling, allowing for better ventilation.