Seismic Risk Analysis Of Baoji City In Consideration Of Hypocentral Location

Seismic risk assessment can reduce the loss of earthquake and has guiding significance for seismic fortification,therefore it is very necessary to assess the risk of earthquake which the building field or structure field may suffer in the future.Baoji is located in the composite transition area of Qinling latitudinal tectonic system and other structural system and also lies in Qinling fold belt,Weihe graben and syncline area of Erdos platform,which leads complex geological structure.So,seismic hazard assessment is an important task in the evaluation of geological disasters in Baoji.However,threatening potential hypocenters,which are around engineering site on different directions,have different characters.Regional geological formation also comes diverse around the site.Therefore,potential hypocenters on different positions must have different earthquake effect;In addition,due to the change of potential hypocenters’ characteristics and the change of seismic wave incident direction,seismic oscillation on different directions must have different effect to the site.Changes of intensity and direction of the seismic oscillation will inevitably lead to different damage of site geotechnical engineering and engineering building.Therefore,in results of seismic hazard analysis,reflection of the effect caused by the position of potential hypocenter to the site has become a very necessary research question.This paper centered Baoji within the range of 150km as the affected zone,fully considering the influence of seismicity and seismic geological structure in the near and far field,then this paper get the activity parameters from the seismic zone and potential earthquake source region by statistical method.Base on the seismic attenuation relationship which is from the western region.The potential seismic sources around Baoji are divided into five directions,and the bedrock acceleration response spectra in different exceeding probability levels are calculated.On this basis,this paper generate unit grids by 0.1 °in study zone,each grid can be regarded as a small engineering site,this paper use "project site seismic safety evaluation software package" from Beijing seismological bureau to analysis.Accordingly,it can get the different exceeding probability corresponding earthquake intensity of different directions in the future period in Baoji.This paper can get results:(1)Seismic risk assessment method considering the potential earthquake source position;(2)Site seismic influence intensity and exceeding probability analysis considering the azimuths of potential earthquake sources around Baoji City,including the bedrock acceleration response spectrum,the seismic peak acceleration and its exceeding probability,etc..Complete seismic risk maps of Baoji City of different azimuths of the different potential earthquake source.