Event summary
The earthquake occurred shortly after midnight local time near Pernik, roughly 20–25 kilometres west of central Sofia. Strong shaking woke residents across western Bulgaria and was also felt in neighbouring countries.
Initial seismic estimates ranged from magnitude 5.6 to 5.8, with a shallow source near the Pernik basin. Later reporting settled around magnitude 5.6 Mw and a depth near 10 kilometres. Depth, local soils and proximity to populated areas contributed to the event being felt strongly despite its moderate magnitude.
Damage and human impact
Damage was distributed across Pernik and nearby communities rather than concentrated in a single catastrophic area. Reports included cracked walls, fallen plaster, broken windows, damaged chimneys and roof tiles, along with isolated partial wall failures. One house in the Rudartsi area was reported destroyed, while a power-plant chimney in Pernik also failed.
- About 30 people received medical attention, generally for minor injuries or acute stress, and were subsequently released.
- A hospital children’s ward was evacuated as a precaution.
- Power interruptions occurred around Radomir before service was restored.
- Water service was disrupted for part of Pernik during the response.
- Rain complicated conditions for homes with roof damage.
- Many residents remained outdoors or in vehicles because of concern about aftershocks.
The final archive update recorded one indirect fatality following a medical emergency immediately after the shaking. This distinction matters: the death was associated with the event’s stress rather than structural collapse.
Aftershocks and response
A substantial aftershock sequence followed. More than 300 events had been recorded by 24 May, though most were too small to be felt. Several reached the magnitude 4 range, including a magnitude 4.3 aftershock late on 24 May. These events prolonged concern but were not reported to have caused major additional damage.
Authorities inspected homes, schools, hospitals and infrastructure in the greater Pernik area. Police patrols were deployed in affected neighbourhoods, while residents cleared plaster, glass and masonry debris. Repair efforts gave priority to public buildings and temporary support for affected households.
How the reporting developed
22 May • First hour
Agencies issued preliminary magnitudes between 5.7 and 5.8. Reports of strong shaking arrived from Sofia, Pernik and surrounding communities as residents gathered outdoors.
22 May • Daylight assessment
The picture shifted from fears of severe destruction to widespread, predominantly non-structural damage. Around 30 people had sought medical care, and inspections began.
23 May • Inspections and recovery
Emergency measures continued while buildings and infrastructure were checked. Rain and interrupted utilities added to local difficulties.
24 May • Extended sequence
Hundreds of aftershocks had been detected. Most were weak, but several felt events maintained public concern.
25 May • Consolidated impact
The archive summary recorded one indirect fatality and confirmed that damage was limited in severity but geographically widespread around Pernik.
Buildings, geology and uncertainty
Bulgaria had seismic design requirements before this event and had adopted European earthquake-resistant standards. Those rules helped frame post-event discussion, but building performance cannot be explained by code provisions alone. Construction age, maintenance, structural system, site conditions and the characteristics of shaking all influence outcomes.
The Pernik basin contains substantial sedimentary deposits, which can modify seismic waves locally. Even so, reports from the event do not establish a single cause for every pattern of damage. Comparisons with earthquakes of similar magnitude elsewhere must account for different soils, structures, rupture properties and distances.
Historical context
The Sofia region has experienced damaging earthquakes before. Historical accounts describe a much stronger sequence in 1858 that caused extensive damage in the city as it then existed. Other documented damaging events affected western and central Bulgaria during the nineteenth and twentieth centuries.
Historical comparisons carry uncertainty because older events were not measured by modern instruments. Their magnitudes and intensities are reconstructed from written descriptions, observed damage and later scientific analysis.
Reading this archive responsibly
Magnitude does not by itself determine damage. A shallow earthquake close to communities may produce disruptive shaking, while building vulnerability and ground conditions can vary over short distances. Early reports also change as agencies receive more station data and responders inspect affected areas.
For definitions of magnitude, intensity and depth, see the earthquake terms glossary. The dedicated Bulgaria earthquake list provides an established country archive.
