The United States Geological Survey recorded a Magnitude 4.5 Earthquake at a depth of 10 km, roughly 9 km to the southeast of the town of Rakovski in Plovdiv Province, in southern Bulgaria, slightly after 2.00 pm local time (slightly after 11.00 am GMT) on Friday 1 May 2020. There are no reports of any damage or injuries arising from this event, but it was felt over most of southern Bulgaria and in parts of northern Greece.
The approximate location of the 1 May2020 Bulgaria, Earthquake. USGS.
The geology of the Balkan Peninsula is complex. Bulgaria lies on the Eurasian Plate, but it is surrounded by a number of microplates created by the collision of Africa with Europe from the south. Southern Greece lies on the Aegean Sea Plate, a breakaway part of the Eurasian Plate, which is being pushed to the southwest by the westward movement of the Anatolian Plate, another breakaway part of the Eurasian Plate underlying Turkey. This is in turn being pushed west by the northeasterly motion of the Arabian Plate, a breakaway part of the African Plate. The western part of the Balkan Peninsula, and the eastern part of Italy are underlain by the Adriatic (or Apulian) Plate, a breakaway part of the African Plate which has pushed like a wedge into southern Europe.
Map showing the movement of the microplates of the eastern Mediterranean. Kotzev et al. (1998).
Thus the rocks of Bulgaria are being pulled to the southwest by the movement of the Aegean Sea Plate and pushed to the northeast by the movement of the Apulian Plate. This has resulted in a number of faults bisecting the country, forming the Pernic Fault Zone, the Vitosha Fault Zone, the Zheleznitsa Fault Zone and the Sophia Graben (a Graben is an area of geological extension).
Map showing the extensive faulting across Bulgaria. Bulgarian Academy of Science/Geological Institute.
Witness accounts of Earthquakes can help geologists to understand these events, and the structures that cause them. The international non-profit organisation Earthquake Report is interested in hearing from people who may have felt this event; if you felt this quake then you can report it to Earthquake Report here.
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