"It has sent a signal that more earthquakes may hit Mae Rim and San Sai districts," Suparerk said.

This morning's earthquake measured 5.1 on the Richter scale and occurred immediately after midnight. Its epicentre was in Mae Rim district. The earthquake was about 33 kilometres deep.

"It's the first time an earthquake has occurred so close to the Chiang Mai city," Suparerk added.

The impact was felt by many.

Mae Jo University students evacuated dormitories and engineers continue to search for structural damage.

Lotus Hotel Pang Suan Kaew staff said the earthquake panicked guests for a short time. Other hotels reported calm.

Mineral Resources Department directorgeneral Apichai Chawacharoenphan warned residents not to panic. "Panic often leads to injuries during an evacuation," he said.

The earthquake was one of the strongest recorded in Chiang Mai. The largest was 5.2 on the Richter scale in December 1995.

Apichai said while Wednesday's earthquake proper was not alarming the number of aftershocks was "unusually high".

"Department officials will look into this and work with other authorities," he added.

Department information will be passed to the Public Works and Royal Irrigation Departments.

Regulations in Chiang Mai, Chiang Rai, Phayao, Lamphun, Lampang, Mae Hong Son, Tak, Nan, Phrae and Kanchanaburi require buildings to be able to with¬stand earthquakes.

"The Public Works Department is seeking to enforce similar rules in Bangkok and its four adjacent provinces," Apichai said.

National Disaster Warning Centre chief Smith Dharmmasaroj said Thailand was home to nine active faults. Earthquakes along some could affect Bangkok.

The Nation