Abstract:This article improves the long-term mean ratio method from the following aspects: First, the abnormal term of the long-term mean ratio method is not included in the denominator of the normal term, highlighting its ability to behave abnormally. Second, the amplitude of the 4th power of X is used as the feature function, making the feature function reflect the characteristics of the phase arrival time. Third, the problem of picking up the phase becomes the problem of finding the maximum value of the characteristic function. Two-way recording jointly picks up S-waves. Fourth, it is proved that the difference between the upper and lower thresholds is obvious when using amplitude quaternion as a characteristic function to pick up seismic phases, and the threshold value of arrival time of seismic phases can be defined as two times the lower thresholds. Finally, it is clearly specified that only three records are used for the short time of the molecule. When the peaks (troughs) of the first arrival and the previous and next maximums, the length-to-time mean ratio must get a maximum, and the time corresponding to the middle data point is the first arrival of the seismic phase. When improved methods are used to pick up 100 seismic records with obvious phases, they all achieve high accuracy. The method in this paper can be regarded as an extension of the time-average ratio method. After the P-wave arrival threshold is determined, it can be used to automatically pick up the P-wave arrival in earthquake early warning.