The National Institute of Geophysics, Geodesy and Geography at the Bulgarian Academy of Sciences said a weak earthquake struck near Slivnitsa at 07:36 am. It had a magnitude of 2.4 on the Richter scale.
There are no reports that people felt the tremor.
The epicentre was 3.3 km from Slivnitsa and 28 km from Sofia. The quake's focus was at a depth of 8 km.