Instrumental intensity as a tool for post-earthquake damage assessment: validation for the strong Vrancea earthquakes of August 1986 and May 1990

Abstract

The frequency-dependent spectrum based seismic intensity, also called instrumental intensity, is calculated basically from the integration of the square values of spectral acceleration ordinates. The values of the instrumental intensity are calibrated to match the values of the EMS-98 intensity scale, providing a promising analytical indicator for estimating the destructive potential of earthquakes. Previous studies have shown that the proposed index could be used as a basis for the development of a new improved seismic intensity scale. The paper presents a set of maps describing the spatial distribution of instrumental intensity ordinates for three seismic events recorded in 1986 and 1990. These events, generated by the Vrancea source, are the strongest earthquakes in Romania for which accelerographic data was recorded at multiple stations. Intensity maps were generated for separate significant frequency bands, in order to reveal the destructiveness of the considered earthquakes for different building categories. Results were compared and correlated with previous studies on Vrancea earthquakes and with information provided by building damage reports from the considered earthquakes