Instrumental Seismic Intensity Isoseismal Generation Method Of Nonuniform Distribution Strong Motion Station

Isoseismal map contains the important information on earthquake source parameters and seismic influence field.Previously,the preparation of seismic intensity maps required combination of field investigation,interpretation of remote sensing of earthquake disasters and strong-motion earthquake observation records,which were invested in manpower,material and time-consuming and dissatisfied the requirements of the timeliness of the seismic intensity rapid reporting.At present,seismic intensity rapid reporting uses the instrumental seismic intensity of strong ground motion records,then calculating the isoseismal map with spatial interpolate method.The spatial distribution of the existing network in our country is not uniform and the network density is low.When the earthquake occurs,the number of stations triggered is small,and the interpolation results are often distorted.In view of the above problems,the Kriging interpolation is improved by using the attenuation law of seismic intensity,where the semivariogram is obtained with the attenuation relation.thesis The characteristics of different network conditions of Kriging interpolation is studied,the reasons for the distortion of Kriging interpolation results are analyzed,and a method based on Voronoi diagram according to the network status of the supplement is proposed.The main contents of this thesis include:(1)The Kriging interpolation method is selected as the research object.The actual earthquake event is calculated by interpolation,and the results are compared with other interpolation methods,so that the superiority of Kriging interpolation on the calculation of isoseismal map can be verified.The problems in the process of mapping of intensity contours with Kriging interpolation are pointed out according to the reality of China's network.(2)It is pointed out that the variogram function of the existing network in China is difficult to regress and fit by studying on construction method of semivariogram of Kriging interpolation,and the attenuation relation of seismic intensity is introduced for construction of semivariogram.The effects of different factors on the results of Kriging interpolation are studied through earthquake intensity field model: Firstly,the method of building semivariogram is given by comparing the influence of semivariogram created by different attenuation relations on the interpolation results;Secondly,the influence of data error on interpolation results are discussed to give the selection criterion of interpolation data;Thirdly,the characteristics of the Kriging interpolation results under the condition of different network are summarized,and the situation which the isoseismal map calculated by Kriging interpolation is not closed is pointed out to propose the intensity points need to be supplemented.Finally,the reason of why Kriging interpolation results are distorted is found out by complting the error analysis of interpolation results,so that the method of supplement points is improved.(3)The method of supplementary points on Kriging interpolation based on Voronoi diagram is put forward.When isoseismal map is not closed,the sparsest position of the network are found by generating station Voronoi map,and a virtual station is added on it to make the isoseismal map closed.In addition,the principle of supplement based on Voronoi diagram is given according to clearance angle range.