Automatic P-wave Arrival Time Detection And Real-time Magnitude Estimation For Earthquake Early Warning

Earthquake early warning(EEW) can quickly release early-warninginformation after a earthquake and reduce the disaster effectively. So far,some countries have built earthquake early warning system(EEWS) whichplayed a direct role. The public has paid special attention to this technology.This paper introduced different types of EEW and domestic and foreignEEWS construction present situation, focused on the methods of seismicphase detection and magnitude estimation. The main contents are as follows:(1) Summarized the main methods of phase identification. Fourmethods are used to detect the P-wave arrival time of Japanese KiK-Netstrong motion records. The results show that the method of algorithm ofSTA/LTA considering AIC paramete has highest accuracy. The pick upaccuracy of the records which noise part contains special signals areimproved after taking some corresponding treatment.(2) Summarized the main methods of magnitude estimation. Themethod of P_dand B-Δ are selected to calculate the magnitude. The resultsshow that the method of P_dis steady and reliability and the method ofB-Δ has slightly larger error than the method of P_d. The peak amplitude Aand corresponding period T of the first three seconds of P wave arecalculated and the A/T with hypocentral distance are used to estimate themagnitude. The results of velocity are in agreement with the displacement.The results of acceleration is the worst.(3) The Fourier transform are usd to analyse the first five seconds of Pwave and corresponding peak amplitude are calculated. Then the magnitudecan be determinate according to the peak amplitude. The results demonstratethat the results of displacement are the best in the same condition and theresults of velocity are better than the acceleration.The longer window wetake, the better results we can get.(4) This paper selects two earthqake in Japan as examples. The P wavearrival time are detected based on the methods STA/LTA considering AICparamete.The Fourier transform are used to get peak amplitude then themagnitude can be calculated. The difference between testing results andactual values are analysed and some important conclusion are summarized inthe end.