The building stock in Bulgaria is extremely vulnerable to earthquakes, according to Professor Emil Botev, head of the Seismology unit of the Bulgarian Academy of Sciences (BAS)
Speaking at an international conference on the catastrophic risks in the country, he claimed that an earthquake around Sofia with a magnitude of 7 or 7+ on the Richter scale would affect over 2 million people.
A 3.6 Richter scale earthquake was felt near the south Bulgarian town of Madan one minute before midnight on Tuesday, said the Geophysics Institute.
According to it, the epicenter was 1 km northwest of Madan, 188 km south east of Sofia, at a depth of 17 km.
There is no information of victims or material damages.
Almost 30 aftershocks have been registered in the northern part of the Aegean Sea after the powerful earthquake which rattled parts of Bulgaria, Greece and Turkey, Saturday.
Most of these were of magnitude 2.5-3.0 on the Richter scale, however some have reached a magnitude of 4.0. The aftershocks occur every 5-10 minutes.
A 2.4 Richter scale earthquake was registered in the Sofia region on Friday night.
The epicenter was around 59 km south of Sofia, near the town of Samokov.
The quake caused no damages and no one was injured.
Earlier on Friday a 2.7 earthquake was registered 15 km from Sofia and on Thursday – a 2.9 Richter scale in the Rila mountains.