Effect Of Site Condition On Rapid Estimation Magnitude In Earthquake Early Warning

At present,earthquake poses serious threat to livesand properties for urban areas and there is no effective method of predicting earthquakes.Earthquake earlying warning(EEW)is a useful tool which can reduce earthquake hazards.An earthquake magnitude could be determined quickly and steady is the most important thing in Earthquake earlying warning.Until now the average period (t_c) and the peak amplitude (P_d) are more popular and useful method than others.A large number of studies have shown that site conditions have a great impact on ground motion,not only affect the amplitude of ground motion also affect the spectral characteristics of ground motion.It can be inferred from this that site conditions also have a great impact on and.In this paper,the influence of the site condition on the method and method is studied,and the correction method of the site condition is proposed according to the research results to improve the accuracy of the warning magnitude estimation.Japan's KiK-net strong earthquake network is different from other networks,because it contains underground drilling station,with detailed drilling information and downhole station has a stable signal to noise ratio and so on.The current methods of estimating the magnitude of the warnings are based on the records of the terrestrial stations.This paper applies the strong earthquake records of the downhole stations to the methods and methods and compares them with the surface stations to find out whether the underground stations are suitable for earthquake warning Of the magnitude estimates Based on this data,the main work of this paper is as follows:(1)Japanese KiK-net station selection and processing of strong earthquake records,this paper from the KiK-net strong earthquake observation network selected in January1997 to December 2012 occurred in Japan,the 179 earthquake events.A total of 3050seismic records(including surface and underground drilling),and the data for baseline correction,P wave picking,filtering and other processing.(2)This dissertation analyzed the effects of data processing on t_c and P_d methods,includeing performance of scaling relations between t_c and magnitude,P_dand PGA/PGV,P_d and magnitude in respect of variation of initial conditions applying for determination of parameter t_c and P_d(length of P-wave window,the band of filter).This dissertation compared the different between the borehole station and free-field station in calculation of t_c and P_d and analyze whether the data form borehole station is better than the free-filed station in terms of stability and reliability.(3)This dissertation analyzed the effects of site conditions on t_c and P_d methods.Two site classification indexes were used in this paper(Vs30,thick overburden).We analyzed effects of site conditions on performance of scaling relations between t_c and magnitude,P_d and PGA/PGV,P_d and magnitude.Trying to propose a correction factor of the site condition makes the early warning parameters more stable and reliable.