An improved STA/LTA algorithm for P wave detection in the 2015 Nepal Earthquake

Abstract

Automatic identification of seismic phases is one of the important tasks in earthquake rapid reporting and early warning. The STA/LTA method is currently the most widely used automatic pickup method. However, the accuracy and stability of its pickup results heavily depend on the selection of feature functions, time window lengths, and trigger thresholds, so it is to some extent impossible to achieve automatic pickup of P-wave arrival time. We present an improved algorithm for automatically picking up P-wave arrival times. In this scheme, the weight factor K is introduced to construct a new feature function, and a method for finding the maximum value on the STA/LTA curve corresponding to the P-wave arrival time is proposed. This method was applied to measure the arrival of the 2015 Nepal Earthquake to validate previous evaluations. The results show that our improved method has the advantage of eliminating the time wasted on adjusting the trigger threshold when picking up the P-wave, which is necessary for the traditional STA/LTA method, and overcoming the challenge of inaccurate prediction when weak seismic signals with a low signal-to-noise ratio occur.