Integrated transnational macroseismic data set for the strongest earthquakes of Vrancea (Romania)

A unique macroseismic data set for the strongest earthquakes occurring since 1940 in the Vrancea region is constructed by a thorough review of all available sources. Inconsistencies and errors in the reported data and in their use are also analysed. The final data set, which is free from inconsistencies, including those at the political borders, contains 9822 observations for the strong intermediate-depth earthquakes: 1940, Mw = 7.7; 1977, Mw = 7.4; 1986, Mw = 7.1; 1990, May 30, Mw = 6.9; 1990, May 31, Mw = 6.4; and 2004, Mw = 6.0. This data set is available electronically as Supplementary data to the present paper.From the discrete macroseismic data, the continuous macroseismic field is generated using the methodology developed by Molchan et al. (2002). The procedure, along with the unconventional (smoothing method) modified polynomial filtering (MPF), uses the diffuse boundary (DB) method, which visualises the uncertainty in the isoseismal boundaries. The comparison of DBs with previous isoseismal maps supplies a good evaluation criterion of the reliability of earlier published maps. The produced isoseismals can be used not only for the formal comparison of the observed and theoretical isoseismals, but also for the retrieval of source properties and the assessment of local responses (Molchan et al., 2011).