An earthquake series in Romania

A fascinating series of relatively shallow minor earthquakes is currently occuring in Romania in the Galaţi area. Around 40 events occured during the last few days, most of them with magnitudes of ~3. Now a mb5.4 earthquake happened in more than 100 km depth. The quake was felt in wide parts of Romania and Bulgaria. Due to its depth no damages are expected. First moment tensor solutions do not give a clear picture yet, but it seems like NE-SW trending thrust event could have happened at the SE bend of the Carpatian Mountains. 

EMSC moment tensor solutions (source: emsc-csem.org)

Few even deeper events have recently been recorded, too. The mb5.4 event of 6 October occurred in the Vrancea seismic zone, which has seen strong and damaging events in the past. The European Archive of Historical Earthquake Data (a wonderful data source, by the way), AHEAD, lists at least 7 historical events with intensities of up to VIII during the deep M7 1894 event (Costantinescu and Marza 1980; Oncescu et al., 1999):

Historical earthquake data for Romania from the AHEAD archive, screenshot of the AHEAD website (http://www.emidius.eu/AHEAD/main/)

The Vrancea seismic zone is Romania’s seismically most active region (see fig. 2 in Constantin et al., 2009 and Constantin et al., 2010). In 1838, another deep and strong event caused intensities of up to IX-X.

References

• Costantinescu L. and Marza V.I., 1980. A computer-compiled and computer-oriented catalog of Romania’s earthquakes during a millennium (984-1979). Revue Roumanie de Geologie Geophysique et Geographie. Ser. Geophysique, 24, 171-191.
• Constantin, A.P., Pantea, A., Stoica, R., Amarandei, C. and Stefan, S. 2009. New data about historical earthquakes occurred on the Romanian territory. Rom. Journ. Phys. 54 (1-2), 239-248.
• Constantin, A.P., Pantea, A. and Stoica, R. 2010. Vrancea (Romania) subcrustal earthquakes: historical sources and macroseismic intensity assessment. Rom. Journ. Phys. 56 (5-6), 813-826.
• Oncescu, M.C., Marza, V.I., Rizescu, M. and Popa, M. 1999. The Romanian Earthquake Catalogue Between 984 – 1997.  Vrancea Earthquakes: Tectonics, Hazard and Risk Mitigation. Advances in Natural and Technological Hazards Research Volume 11, 43-47.

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