The intensity assessment of the April 25, 2009, Vrancea subcrustal earthquake from macroseismic data

摘要

On April 25, 2009, at 20:18:48 (local hour) the Romanian territory was shaken by a moderate size earthquake centred beneath the bending area of the south-eastern Carpathians, in the Vrancea seismogenic region (Romania). In the present paper we present intensity map, macroseismic intensities, and community observations of effects for the M_(W) =5.4 Vrancea subcrustal earthquake of 25 April, 2009. For many locations, for the estimation of the macroseismic intensities besides questionnaires other type of sources such as press reports, internet were used. The highest intensity assigned for this Vrancea earthquake was VI MSK, estimated for eleven locations, situated in the north-eastern part of Vrancea seismogenic zone, which include parts from Vrancea, Bacau, and Galati counties. At the lowest intensities, the 2009 earthquake was felt to a distance of 500 km from the epicenter, in Rep. of Moldova, Bulgaria, Ukraine, and Serbia. A non-uniform distribution of intensity resulted for locations on different directions from the epicenter. A scatter of as much as one-two intensity units were observed for places situated very close. The comparison of the intensity areas for the October 27, 2004 and April 25, 2009 moderate subcrustal earthquakes of the Vrancea seismogenic zone was performed.