Seismicity and seismic hazard assessment in Greece

Greece is the most seismically active region in Europe and also rank high (sixth position) on a global scale (Tsapanos and Burton, 1991). Hence reliable seismic hazard assessments are important for sustaining the economical developments of a country like Greece. The objective of such studies and modeling efforts are to obtain long term probabilities of occurrences of seismic events of specified sizes in given time interval. Primary information for hazard assessments is extensive historical seismicity observations which in case of Greece and adjacent areas dates back to 550 years B.C. Descriptions of the macroseismic effects of several strong earthquakes in this region which occurred between 550 BC - 300 AD have been recovered more recently. As we go back in time the historical records become progressively incomplete and naturally reflects destructive earthquakes in populated areas. Instrumental observations are important in a hazard context both for delineating active faults and also for estimating crustal attenuation properties. Description of the macroseismic effects of several strong earthquakes which occurred in the broad area during the time period 550 BC-300 AD have been found. In this presentation, I summarize seismic hazard assessment efforts for Greece and give details on shallow and intermediate depths seismicity, maximum observed and expected macroseismic intensities, peak ground accelerations, velocities and displacements. Also strong motions duration are discussed and macroseismic intensity decay with distance for given magnitudes are outlined. The earthquake activity in Greece has an uneven spatial distribution and this is taken into account in the presentations of various hazard measures and their describtions.