The earthquake early warning (EEW) system is difficult to provide consistent magnitude
estimate in the early stage of an earthquake occurrence because only few stations are
triggered and few seismic signals are recorded. One of the feasible methods to measure the
size of earthquakes is to extract amplitude parameters using the initial portion of the
recorded waveforms after P-wave arrival. However, for a large-magnitude earthquake (M w>
7.0), the time to complete the whole ruptures resulted from the corresponding fault may be …