GNGTS 2016 - Atti del 35° Convegno Nazionale

282 GNGTS 2016 S essione 2.1 magnitude. The effect of uncertainties in this parameters have been introduced by considering alternative realizations of the seismicity model and considering the 50 th , 5 th and 95 th percentiles as representative of the median and associated uncertainties of the final seismicity model. Finally I compare the seismicity rates predicted by the model with the historical seismic release as documented in the recently released CPTI15 catalogue (Rovida et al ., 2016) for various spatial and temporal scales and for different declustering approaches. I also discuss the advantages (independence from seismological data) and limitations (uncertain seismogenic depth, Mmax, and fraction of aseismic deformation ) of the proposed geodetically-derived seismicity model. References Gutenberg, B., and C. F. Richter (1944), Frequency of earthquakes in California, Bull. Seismol. Soc. Am. , 4 , 185– 188. Kagan, Y. Y. (2002), Seismic moment distribution revisited: II. Moment conservation principle, Geophys. J. Int. , 149 (3), 731–754, Kagan, Y.Y. (2002), Seismic moment distribution revisited: I. Statistical results, Geophysical Journal, 148(3), 520- 541. Kostrov, V. V. (1974), Seismic moment and energy of earthquakes, and seismic flow of rock, Phys. Solid Earth, 1, 23–44. Molnar, P. (1979), Earthquake recurrence intervals and plate tectonics, Bull. Seismol. Soc. Am., 69, 115–133. Rovida A., Locati M., Camassi R., Lolli B., Gasperini P. (eds), 2016. CPTI15, the 2015 version of the Parametric Catalogue of Italian Earthquakes. Istituto Nazionale di Geofisica e Vulcanologia. doi :http://doi.org/10.6092/ INGV.IT -CPTI15 Shen, Z.K., Wang, M., Zeng, Y., and Wang, F. (2015) Optimal Interpolation of Spatially Discretized Geodetic Data, BSSA� ���� ���������� ����������������������� , 105, 2117-2127, doi:10.1785/0120140247. Ward, S. N. (1998), On the consistency of earthquake moment release and space geodetic strain rates: The United States, Geophys. J. Int. , 134 (1), 172–186. TESTS FOR THE OPTIMIZATION OF PEAK GROUND MOTION ATTENUATION RELATIONSHIPS FOR GREECE V. Del Gaudio 1 , K. Chousianitis 2 , P. Pierri 1 1 Dipartimento di Scienze della Terra e Geoambientali, Università degli Studi “Aldo Moro”, Bari, Italy 2 Institute of Geodynamics, National Observatory of Athens, Athens, Greece An updated database of recordings acquired by the Greek accelerometer network was used to re-define attenuation relationships for peak horizontal acceleration and velocity (PHA and PHV), to be used in earthquake scenario predictions and seismic hazard assessment for the Greek area. A two-stage approach (Joyner and Boore, 1993) was employed in data regression to separate the determination of parameters that model the influence of source properties from those representing the effect of wave propagation. This approach is used to counter the bias due to the uneven sampling of magnitude-distance within the regression dataset, with prevalence of weak events-short distances and strong events-long distances combinations, which could lead to underestimate attenuation rates (see Fukushima and Tanaka, 1990). Different functional forms were tested starting from a general equation having the form (1) where M is the event moment magnitude, R the epicentral distance in km, s i and m j are N and M dummy variables for site and focal mechanism types, respectively, ε r and ε e are the estimate errors related to unmodelled intra- and inter-event variability, respectively.