| Abstract: | This paper evaluates possible directional effects from strong ground motions recorded during the last four significant subcrustal earthquakes produced in the Vrancea seismic zone(Romania) in August 1986(M_w=7.1),May 1990(M_w=6.9 and 6.4) and October 2004(M_w=6.0).Several measures of the horizontal component of the ground motion given in the literature(Boore et al.,2006;Boore,2010) are computed and are related to the geometric mean of the as-recorded horizontal components.ANOVA method is applied in order to quantify the influence of the earthquake magnitude and of the soil class on some strong ground motion parameters(e.g.Arias intensity,PGV/PGA,or mean period T_M).The study of the directional effects is performed using the distribution of I_(JMA) and of the rotation angle corresponding to a measure of the horizontal component of the ground motion(RotD 100) and the results reveal a visible directional pattern for I_(JMA),while in the case of RotD100 the directional patterns are less visible. |
