以振幅为特征函数拾取P波、S波震相

Picking P-wave and S-wave Phase with Amplitude as Eigenfunction

从以下几个方面对长短时均值比法进行改进:1)使长短时均值比法作为分子的异常项不包含在作为正常项的分母中,突出其表现异常的能力;2)用振幅的4次方作为特征函数,使特征函数体现震相到时特点,拾取震相到时问题转化为寻找特征函数最大值问题;3)仅用竖直向记录拾取P波,用东西、南北两向记录联合拾取S波;4)定义用长短时均值比拾取有效波的第一个峰值为拾取到时阈值的上限,拾取干扰波最大峰值为阈值下限,证实了用振幅4次方作为特征函数拾取震相,其阈值上、下限相差明显,可以定义地震震相到时阈值为阈值下限的2倍;5)明确规定分子的短时间仅仅采用3个记录,当3个记录点包含震相初至的波峰(波谷)和前后次极大值时,长短时均值比一定可得到一个极大值,中间的数据点对应的时刻为震相初至。用改进的方法拾取100个有明显震相的地震记录震相到时,准确度很高。本文方法可以视为是对长短时均值比法的拓展,在确定P波到时阈值后,可以用于地震预警工作中的P波到时的自动拾取。

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.