A 4.5-magnitude earthquake struck western Bulgaria at 3.52 p.m. on Saturday, according to the European Mediterranean Seismological Centre.
The epicenter of the quake was 7 km southeast of Pernik and 19 kilometers west of Sofia, very near to the epicenter of the 5.8-magnitude jolt which hit the region in the small hours of May 22.
Saturday's quake occured at a depth of 10 kilometers and aftershocks may occur in the next few hours.
A strong 5.8-magnitude quake struck south-west of Bulgaria's capital Sofia shortly after 3.00 am (00.00 GMT) on May 22.
Its epicenter was about 6 km from the city of Pernik and some 25 km from Sofia.
The quake was followed by numerous slight aftershocks.
Even though the jolt resulted in no casualties, it caused damages worth some BGN 3 M.