A Comparison of Two Magnitude Estimation Methods Using Predominant Period in Earthquake Early Warning

Currently, there are two magnitude estimation approaches using predominant period for earthquake early warning, Tpmax method and Tc method. We compared Tpmax method with Tc method from the NSMP strong motion records of 22 earthquakes in United States with moment magnitude ranging from 4.1 to 7.9, to explore which method was with higher precision and could be suitable for the earthquake early warning system. Our results show that scaling relations between the two predominant period parameters, Tpmax and Tc, calculated from P-wave arrivals and earthquake magnitude are consistent with previous research. It was found that Tc method had higher precision than Tpmax method with the same filter band, and had best result in magnitude estimation resulting in a correlation coefficient of 0.78 and a standard deviation of 0.16 using 3 seconds signal after the P-wave arrival. We also found that Tc method without low-pass filter had higher accuracy than Tpmax method without low-pass filter. We recommended Tc method using 3 seconds signal after the P-wave arrival as the priority magnitude estimation method for earthquake early warning.