CORRELATIONS BETWEEN MACROSEISMIC INTENSITY VALUES AND GROUND MOTION MEASURES OF VRANCEA (ROMANIA) SUBCRUSTAL EARTHQUAKES

The correlations between macroseismic intensity (MI) and strong ground motion parameters such as Peak Ground Acceleration (PGA) and Peak Ground Velocity (PGV) for the Vrancea subcrustal earthquakes are compared. The recent Romanian earthquakes, especially Vrancea earthquakes provide valuable data to examine the correlation relationships between these parameters for the entire territory of Romania. The goal of this study is to develop a new empirical relationships between the strong ground-motion records and the observed intensities for major and moderate earthquakes with Mw >= 5.4 and epicentral intensity in the range VI to IX MSK degrees that occurred in the period 1977-2009. For each instrumental record we assigned a macroseismic intensity based on the proximity of the site where reported value are available (no more than 3 km distance around the station). The obtained relations between macroseismic intensity and PGA/PGV will be given both as a mathematical equations, but also as corresponding ground motion intervals. The most prominent results available in the literature have shown that macroseismic intensity and ground parameters do not always show a one-to-one correspondence, and the errors associated with the intensity estimation from PGA/PGV are sometimes +/-2 MSK degree. These relations can be used as near realtime response regarding ground shaking severity, and potential damages in the areas affected by the Vrancea earthquakes.