Estimation Of Magnitude Using Characteristic Parameters For The Earthquake Early Warning Of High Speed Railways

Earthquake early warning（EEW） is an effective approache for mitigating the seismic hazard of high speed railways, which plays an important role for the safe operation of high speed railways and mitigating the seismic hazard. Fast and accurate estimation of magnitude is a basic work for the research and application of earthquake early warning. At present, the estimation of magnitude based on the P wave of single station exists some problems, including that the discrete of estimating results is too high, overestimate the small earthquakes and underestimate the large earthquakes, this becomes a basic object need to be addressed for playing the function of earthquake early warning. This paper mainly uses the strong motion records from K-net network in Japan, based on the several seconds’ earthquake information after the arrival of P wave, studys the statistical relationship between various characteric parameters and magnitude, an overview of the research is as follows:1. Introduce the current situation of estimating magnitude based on the P wave of single station, use single characteric parameterτ_c、τ_p^maxand P_d to make linear regression and weighed fit for magnitude. The results show that when epicentral distance and focal depth are considered at the same time in P_d method, the accuracy of calculation is higher, and the underestimated phenomenon of big earthquake has improved after weighting process.2. Calculate magnitude of one second to ten seconds after the arrival of P_d wave, the results show that the calculating accuracy of P method improved obviously along with the increasing time, and the calculating accuracy is better than the others.3. Estimating magnitude using combinations of multi-parameters, including P_v、P_d、τ_c、τ_p^max and R, we calculate the combinations of two and three parameters, the results show that the discrete of multi-parameters is smaller than the corresponding single parameter, and the calculating accuracy of combinations of P_d、τ_c and R is best.4. Calculate the threshold of P_d according to the peak ground acceleration of high speed railways for safe operation, divede magnitude into several segmentations using characteric parameter P_d, select several magnitude critical points of warning earthquake initially, determine the masgnitude critical point as six according to the distribution of error finally.