an aspect of envelope curve of initial p-waves for earthquake early warning system

One of the vital tasks in the earthquake early warning (eew) system is rapid and precise estimation of earthquake magnitude and distance. the japanese eew called the urgent earthquake detection and alarm system (uredas), is used by railways in order to stop high-speed trains (nakamura, 1988). in the uredas, the event magnitude is determinedby applying well-known method namely predominant period (tp max) on the initial seconds of arriving p-waves, which was introduced by allen and kanamori (2003).