Rapid Magnitude Estimation On Earthquake Early Warning

Earthquake early warning (EEW) is a new technology which is used forearthquake disaster mitigation, it has the potential to reduce the casualties andthe losses by earthquake disasters. Rapid estimation of Magnitude is the keytechnology of the EEW, it influence the alarm release and can be used topredict the ground motion of the target area. This paper focuses on the methodof seismic phase automatic detection and magnitude determination, studies onhow the size of magnitude and hypocenter distance influence the result ofmagnitude determination on earthquake early warning system. The maincontents and conclusions are as follows:(1) Base on the research of seismic phase automatic detection, themethods of STA/LTA and AIC are used together to detect the P-wave phase,and the result of P-wave phase detection is relatively accurate with a smallererror to the result of manually detection. The result of P-wave phase automaticdetection is regarded as an actual result.(2) Base on the research of rapid magnitude estimation, the methods ofTp (predominant period) and Pd (peak displacement amplitude) are used todeterminate the magnitude, and the result shows that the method of Pd has abetter performance with better stability and lower degree of dispersioncompared with the method of Tp.(3) The effective use of S-wave phase which is near the source ofearthquake can revise the magnitude determined by the P-wave phase.Amount of strong motion records are classified according to magnitude andhypocenter distance, parameters of magnitude determination are computed tofit magnitude. The result of magnitude fitted in accordance with differentlength of P-wave and S-wave phase are analyzed, then the right time length isfind to determine magnitude.(4) Base on the amplitude parameters of P-wave and S-wave on vertical,horizontal and three components, the fitting results in terms of differentsections for magnitude and hypocenter distance area are compared，thenstandard deviations of fitting magnitude on different component are comparedand influence of different component is analyzed. Comprehensiveconsideration of the stability and standard deviation of fitting results, the threecomponents of P-wave and S-wave are recommended to determine magnitudeon earthquake early warning. The influence of hypocenter distance is analyzedwithin the same magnitude section.(5) Parameters computed from strong motion records within the samehypocenter distance section are fitted to magnitude, with the purpose ofanalyzing how magnitude influence magnitude determination, the fittingresults between different magnitude areas and whole magnitude area are compared, Results show that the fitting results of P-wave within differentmagnitude section and whole magnitude section are not agreed, the fittingresult within different magnitude is a gentle curve with apparent magnitudesaturation, but the fitting results of S-wave are agreed without apparentmagnitude saturation.