Study On Computing Method Of Instrumental Seismic Intensity

Seismic intensity is used to measure the strength of earthquake ground motion and its impact.The on-site macro seismic intensity assessment requires a lot of manpower and material resources and takes long time.The ambiguity of the intensity assessment index and the subjectivity of the assessors often cause differences of assessment results.Instrumental seismic intensity assessment based on the observation records of strong earthquakes can quickly and objectively assess the degree of damage near the earthquake stations.Based on the ground motion data of Northridge Earthquake in 1994,Wenchuan Earthquake in 2008,Kaikoura Earthquake in 2016 and Ridgecrest Earthquake in 2019,This article studies on instrument seismic intensity calculation method,the relationship between Modified Mercalli Intensity?MMI?and the main parameters of ground motion and the drawing of intensity contours based on the Kriging method.The main work and results are as follows:?1?The MATLAB program of typical instrumental seismic intensity algorithms?Calculation Code for Instrumental Seismic Intensity of China Earthquake Administration,Shake Map,Japan Meteorological Agency Instrumental Seismic Intensity,and Fujian Provincial Earthquake Agency Instrumental Seismic Intensity?has been compiled.This article calculates instrumental seismic intensity by using the ground motion data of over 50 gal of Wenchuan Earthquake,and compared the result of instrumental seismic intensity with the on-site investigation intensity.?2?The relationship between the reference acceleration(a₀and a_0.5)and PGA,PGV is studied.The results show that the correlation between a₀and PGV is better than a_0.5,and The correlation between a_0.5and PGA is better than a₀.The research results show that the a₀corresponding to the filtering range of 0.5-10Hz and the reference duration of 0.3s is more stable.?3?This article studies on the relationship between MMI and the main parameters of ground motion based on the least square method,.The results show that MMI has a good correlation with the mean of the main parameters of ground motion.The segmented model of instrumental seismic intensity was studied based on the segmented regression method.The results show that the instrumental seismic intensity segmented model greatly improves the fitting effect of data in high-intensity areas and improves the accuracy of MMI estimation.?4?Taking Northridge Earthquake in the United States as examples,This article studies the method of drawing intensity contour maps based on the Kriging method.The results show that the intensity contour maps drawn by the spherical model are better for Northridge Earthquake.