Probabilistic seismic hazard assessment in Greece – Part 1: Engineering ground motion parameters

Abstract

Abstract. Seismic hazard assessment represents a basic tool for rational planning and designing in seismic prone areas. In the present study, a probabilistic seismic hazard assessment in terms of peak ground acceleration, peak ground velocity, Arias intensity and cumulative absolute velocity computed with a 0.05 g acceleration threshold, has been carried out for Greece. The output of the hazard computation produced probabilistic hazard maps for all the above parameters estimated for a fixed return period of 475 years. From these maps the estimated values are reported for 52 Greek municipalities. Additionally, we have obtained a set of probabilistic maps of engineering significance: a probabilistic macroseismic intensity map, depicting the Modified Mercalli Intensity scale obtained from the estimated peak ground velocity and a probabilistic seismic-landslide map based on a simplified conversion of the estimated Arias intensity and peak ground acceleration into Newmark's displacement.

Probabilistic seismic hazard assessment in Greece – Part 2: Acceleration response spectra and elastic input energy spectra

“…The seismogenic model used in the present study was well defined in the first part of this study (Tselentis and Danciu, 2010a). In summary, the model relies on the 67 seismogenic source zones proposed by Papaioannou and Papazachos (2000) and their seismicity parameters derived from the Greek catalogue thought to be complete for moment magnitudes M≥8.…”

“…The spatial distribution of the Greek catalogue within the selected seismic source zones, together with the associated fault mechanism is presented in Fig. 1 of Part 1 of this investigation (Tselentis and Danciu, 2010a). A focal depth of 10 km was adopted for all seismogenic source zones.…”

“…Following the current PSHA practice we have directly incorporated the standard deviation into the PSHA calculation, and we have imposed cut-off limits of median plus and minus three standard deviations, to the "right-tail" of the lognormal distribution which tend to reach infinity. The functional form and the coefficients of the selected regression models are presented in Table 1 of Part 1 of this investigation (Tselentis and Danciu, 2010a). In this approach, PSHA's are conducted for response spectral values covering the periods from 0.1 s to 2.5 s were carried out for SA and from 0.1 s to 2.0 s for VE i .…”

“…The PSHA process involves an integration of the potential earthquake shaking from all possible source locations and magnitudes for some area around a site to calculate the probabilities of various levels of ground shaking at the site. The main elements in seismic hazard analysis comprises a set of seismotectonic source zones developed from a seismotectonic model of the study region; magnitude-recurrence relations for each of these zones; functional relations for the magnitude and distance dependence of the selected strong-motion parameters; and an analytical technique for computation of the ground motion parameters at the selected points throughout the region at desired probabilities of exceedance (Tselentis and Danciu, 2010a). In order to estimate the probability of ground motion on a regional scale, earthquakes within a seismic source are typically assumed to occur randomly over time unless the historical or geological record indicates nonrandom occurrence (Thenhaus and Campbell, 2003).…”

“…4 corresponds to a region of high seismic zone, (reference PGA = 0.36 g), estimated in bedrock (soil category A) and 5 % damping. The UHRS in terms of SA computed for the selected cities were normalized with the PGA computed in the first part of the study of Tselentis and Danciu (2010a).…”