GNGTS 2013 - Atti del 32° Convegno Nazionale

observed for the events having M L equal to 3.0 and 4.0 are in good agreement with the ones predicted by our equation. The figures also suggests that the estimated attenuation model for R epi < 15 km predicts slightly higher PGA values at very short epicentral distance for the events having magnitude higher than 3.6, that is the M ref . Tab. 1 – Regression coefficients for horizontal PGA. 2s represents the 95% confidence interval. b 1 b 2 b 3 b 4 b 5 h b 6 e C e D e r 2 Epicentral distance < 30 km; soil classes B, C, and D (960 PGA values). 0.946 0.594 -0.050 -2.473 0.468 3.258 0.017 -0.480 -0.033 0.377 0.743 m-2s -0.850 -0.122 -0.150 -3.509 0.205 1.720 -0.011 -0.669 -0.101 m+2s 2.742 1.309 0.051 -1.436 0.732 4.797 0.045 -0.292 0.035 Epicentral distance < 30 km; soil classes B and D. 0.914 0.639 -0.059 -2.482 0.480 3.301 0.017 - -0.033 0.378 0.735 m-2s -0.916 -0.086 -0.161 -3.550 0.212 1.731 -0.012 - -0.102 m+2s 2.745 1.364 0.043 -1.413 0.749 4.871 0.046 - 0.035 Epicentral distance < 30 km); soil class B. 0.124 0.814 -0.071 -2.067 0.399 2.725 0.005 - - 0.383 0.742 m-2s -1.670 0.034 -0.182 -3.009 0.131 1.146 -0.022 - - m+2s 1.919 1.593 0.040 -1.125 0.666 4.304 0.032 - - Epicentral distance < 15 km; soil classes B, C, and D (662 PGA values). 0.151 0.415 0.011 -1.487 0.234 2.043 -0.023 -0.589 -0.052 0.353 0.694 m-2s -1.887 -0.375 -0.102 -3.097 -0.087 -0.296 -0.091 -0.840 -0.130 m+2s 2.190 1.205 0.124 0.122 0.555 4.381 0.045 -0.337 0.025 Epicentral distance < 15 km; soil classes B and D. -0.042 0.508 0.000 -1.494 0.198 2.037 -0.023 - -0.051 0.353 0.686 m-2s -2.078 -0.292 -0.114 -3.116 -0.124 -0.322 -0.092 - -0.128 m+2s 1.994 1.308 0.115 0.129 0.519 4.396 0.045 - 0.027 Epicentral distance < 15 km; soil class B. 1.068 0.666 -0.009 -3.946 0.091 3.881 0.078 - - 0.354 0.686 m-2s -2.760 -0.247 -0.132 -8.247 -0.354 0.964 -0.075 - - m+2s 4.897 1.579 0.114 0.356 0.535 6.798 0.232 - - Discussion and summary. The territory of the Catania province surrounding he volcanic area of Mount Etna, is characterized by the presence of densely populated towns and by a wide dissemination of industrial and agricultural facilities that sustain the economy of east Sicily. Due to vivid tectonic activity both on a regional as well as local sale, the area belongs to the one with the highest seismic hazard in Italy. Nonetheless, there are no published attenuation relationships available for the investigated area, in particular for the shall events which, though being of small magnitude, cause severe damage to the population living at the feet of the volcano. Here we summarize the preliminary results we obtained for ground-motion predictive equations calibrated for the very shallow events, and at short epicentral distances We have estimated GMPEs by using a dataset of 54 shallow earthquakes recorded by the seismic stations of RSPSO network. Magnitudes of considered events range from 2.5 to 4.3. The available dataset is made up of peak ground horizontal acceleration (PGA) parameters 156 GNGTS 2013 S essione 2.1