The geophone can daily detect a large amount of microseismic signals and it is time consuming for manual picking the arrival times of P-S waves. We propose an automatic P-and S-wave onset picking method based on single-component geophone, which is widely used in mines. Firstly, we filter the original signal with a Butterworth bandpass filter in order to increase the SNR. The mine microseismic signal frequency ranges from 10 Hz to 2000 Hz, so we choose the band-pass filter interval to be 3-2400 Hz. Secondly, we need to locate the P-S wave phases in the signal. An improved characteristic function can strengthen the change of frequency and amplitude. We define two neighboring windows of different sizes, with the short time window lying in the end of the long time window. Then we compute the average value of the characteristic function within the window, which is also called STA/LTA (short-term average value/long-term average value). With the sliding of the long-short time window, we can get the positions of the P-S wave onset windows. The ratio of STA/LTA will have two peaks because the arrivals of P wave and S wave. Through a preset threshold, we can locate two time windows including P wave onset time and S wave onset time, respectively. In the last step, Akaike's information criterion(AR-AIC criterion) is used in the two time windows, the global minimum of AIC in the window is the arriving time. We have tested this method with one thousand single-component microseismic signals, the result has shown that 71% of P-wave arrival time picking is correct and 79% of S-wave picking is correct.

single-component signal  /  STA/LTA  /  AR-AIC criterion  /  P-wave onset  /  S-wave onset