Empirical Relationships between Modified Mercalli Intensity and Engineering Ground-Motion Parameters in Greece

Abstract New relationships between modified Mercalli intensity (MMI) and engineering ground-motion parameters are developed for Greece. The ground-motion parameters investigated were peak ground acceleration (PGA), velocity, displacement, Arias intensity, and cumulative absolute velocity. The observed earthquake intensity is quantified in terms of the observed MMI at the recording station and the data set consists of 310 time histories recorded from 89 Greek earthquakes. The selected records were found to be characterized by high-frequency, low-energy content and short duration. Two sets of empirical relationships between MMI and the selected ground-motion parameters were derived. The first set of MMI predictive equations are independent of magnitude and epicentral distance, and they were derived by fitting the mean values of the ground-motion parameters using a weighted least-squares regression technique. The influence of magnitude, epicentral distance, and the local site conditions were incorporated into the second MMI predictive model, resulting in a decrease of the model variance. The lowest standard deviation observed for the first MMI predictive model was for PGA, while for the second MMI predictive model, Arias intensity exhibited the smallest variability. Another finding of the present study was that the local site effect has a little influence on the MMI predictive model for peak ground velocity (PGV). The proposed predictive equations are valid for MMI values IV–VIII, and some of them might be used for rapid assessment of the ground shaking and mapping damage potential.