Automatic seismic wave arrival detection and picking with stationary analysis: Application of the KM2O-Langevin equations

Abstract

Abstract An automatic detection and a precise picking of the arrival times of seismic waves using digital seismograms are important for earthquake early detection systems. Here we suggest a new method for detecting and picking P -and S -wave signals automatically. Compared to methods currently in use, our method requires fewer assumption with properties of the data time series. We divide a record into intervals of equal lengths and check the “local and weak stationarity” of each interval using the theory of the KM 2 O-Langevin equations. The intervals are stationary when these include only background noise, but the stationarity breaks abruptly when a seismic signal arrives and the intervals include both the background noise and the P -wave. This break of stationarity makes us possible to detect P -wave arrival. We expand the method for picking of S -waves. We applied our method to earthquake data from Hi-net Japan, and 90% of P -wave auto-picks were found to be within 0.1 s of the corresponding manual picks, and 70% of S -wave picks were within 0.1 s of the manual picks. This means that our method is accurate enough to use as a part of the seismic early detection system.