LISBON, Jan. 15 (Xinhua) -- Schools in the Portuguese town of Arraiolos were evacuated on Monday after an earthquake registering 4.9 on the Richter scale struck the area.

No injuries or major structural damage have been registered, though local media reported a sense of shock and some communities have lost electricity. Teachers and students were being sent home merely as a precautionary measure, a schools spokesperson told the Portuguese Lusa News Agency.

The earthquake occurred at 11:51 a.m.local time (1151 GMT). Its epicenter lay 6 kilometers north of Arrailoas, which is 130 kilometers to the east of Lisbon.

Six smaller tremors followed, registering between 1.3 and 2.5 on the Richter scale, according to the Portuguese Institute of Sea and Atmosphere (IPMA).

A 4.9-magnitude earthquake is classified as "light", while 5.0 would have been "moderate".

In 1755, an 8 to 9-magnitude earthquake all but destroyed Lisbon. Experts say the region remains vulnerable to seismic activity.