Abstract:The first step to realize earthquake early warning is to pick P-wave arrival time quickly, accurately, and automatically. In the current automatic methods of picking up P-wave arrival time, the anti-interference ability needs to be encountered; thus, in this study, the short-term average/long-term average (STA/LTA) method for detecting amplitude changes is proposed for picking up P-wave arrival times. The study shows that compared with the Allen algorithm, the amplitude change can be used as the characteristic function to highlight the mutation feature of seismic wave arrival time. Moreover, using the STA/LTA method, the pick-up deviation of seismic wave arrival times caused by the interference can be reduced. Analyses of anti-interference in the STA/LTA method and Allen algorithm show that in the presence of a large amplitude interference, the Allen algorithm cannot pick up P-wave arrival times because the peak value does not appear in the P-wave first arrival position; however, the anomaly in the P-wave arrival time position is still obvious when using the proposed method. Under less amplitude disturbance, the two methods are used to pick up the P-wave arrival time of 160 MS ≥ 4.0 earthquakes, and the accuracy of the new method is slightly higher. The new method can be seen as an extension of the STA/LTA transform method.
