The Study On The Ground Motion Attenuation Law Of Moderate Earthquake Area

Ground Motion Attenuation Relationship is a key factor of assessment seismic hazard, especially of compiling seismic zone map. The current Ground Motion attenuation relationship was obtained based on the magnitude great equal to 6 without considering the attenuation features of moderate earthquake. The moderate earthquake area covered almost one third area of mainland China but the study on Ground Motion attenuation relationship for this area still dispersed to some small regions. Therefore, this paper is try to get the intensity and Ground Motion attenuation relationship through collecting intensity records of this region and taking reference from previous study about this area.Firstly, this paper reviews the attenuation law's research history and the current situation of moderate earthquake area's attenuation relationship of China, expounds the necessity of this study.Secondly, this paper selects intensity isoseismic line data from the moderate earthquake area. After carefully treatment of this intensity records, a single variable weighted least square regression method was used to determine the intensity attenuation relationship of moderate earthquake area.Thirdly, taking Western United States as reference region, the Ground Motion data were obtained by the Mapping method and Ground Motion attenuation relationships of PGA and EPA were obtained accordingly by using a new regression method named improved two step method which was first given by this paper.Finally, the stochastic method haven been used to simulate the Ground Motion (Peak horizontal acceleration) of the moderate earthquake area. Comparison haven also been made between the data which were obtained from the Mapping method and the data from the stochastic method.