Image
© USGS
The relatively strong tremor that threw into panic people in Bulgaria's capital Sofia and nearby Pernik is an aftershock of the 5.8-magnitude quake at the end of May, according to experts.

"What we experienced on Saturday is an aftershock of the earthquake of May 22 this year and has the same epicenter," Professor Nikolay Miloshev, director of the National Institute of Geography, Geophysics and Geodesy, Sofia, explained.

In his words it is not unusual that today's earthquake is related to the May tremor because it was very strong and even then seismologists predicted aftershocks may continue for months.

Saturday's earthquake was estimated as 4.5 on the Richter scale by the European Mediterranean Seismological Centre and as 4.2 on the Richter scale by the Geophysical Institute at the Bulgarian Academy of Sciences (BAS).

The jolt struck at 3.52 p.m. and was felt in Pernik, Sofia, Samokov, Montana and Plovdiv.

The quake occurred at a depth of 10 km and was epicentered 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.