Parametric Criteria in Onsite Earthquake Early Warning System

Abstract

In recent years, rapid estimation of Peak Ground Motion (PGM) and Modified Mercalli Intensity (MMI) based on a few seconds of the initial portion of wave has been studied as the most important part of the onsite Earthquake Early Warning (EEW) systems studies. To establish an onsite EEW, we need the empirical relationship between earthquake size, PGM and epicentral distance in real-time mode. In some EEWs, the epicentral distance is estimated from the amplitude growth rate of a few seconds of P waves. Many studies have empirically confirmed that the growth rate becomes smaller as epicentral distance becomes far. This relation is true regardless of the earthquake size. In the current study, five parametric criteria including , , , and are proposed for quick detection of destructive oncoming strong motions at a specific target based on ground motions of the first 4 seconds of Japan event waveforms where and parameters represent the characteristics of wave envelope curve in a simple function with the form of . In this study, parameter is inversely proportional to epicentral distance which can be readily estimated within a given short time after P waves’ arrival. , and are the initial peak ground acceleration, velocity and displacement, respectively. The current study represent five thresholds parameters including , , , and in order to warn a Peak Ground Velocity ( ) greater than about 10 cm/sec which are clustered in strong shaking with Modified Mercalli Intensity ( ) larger than . Therefore, destructive earthquakes can be detected form the maximum amplitudes and growth rate of few seconds of P waves by using mentioned parametric criteria.