Rupture directivity effect on the seismic ground motion parameter during Italy M_W6.6 earthquake on October 30，2016

On October 30, 2016, another shallow-source M_W6.6 earthquake occurred in cen-tral Italy after August 24 M_W6.2 earthquake. A large number of three-component acceleration recordings of strong ground motion were collected by Italian strong-motion network and were downloaded from Engineering Strong Motion database （ESM） and analyzed by the base-line correction, filtering and other conventional data processing. Strong motion observation stations were divided into two groups as front rupture area NW and rear rupture area SE according to the focal mechanism solutions. Attenuation relationships of ground motion parameters, including amplitude, response spectrum and durations, were regressed by using the least squares method in the different two groups and we found that acceleration amplitude was affected by rupture directivity remarkably, and the amplitude and response spectrum of acceleration in the NW group were greater than those in the SE group in the case of the same Joyner-Boore distance R_JB, while the duration in NW group was more less than that in SE group. In conclusion, near-source ground motion recordings were much rich and the characteristics of strong ground motion were greatly influenced by rupture directivity.