DETECTION OF P- AND S-WAVE ARRIVAL TIMES USING THE DISCRETE WAVELET TRANSFORM IN REAL SEISMOGRAMS

Abstract

In this study, a novel solution based on discrete wavelet transform is introduced to determine P- and S-wave arrival times. An algorithm is developed based on changes in frequencies and energy in high frequency bands. Firstly, the earthquake seismogram is divided into a series of windows of 256 samples in length, neighboring windows overlapping by 128 samples. Next, each window is decomposed to its high frequency and low frequency components using discrete wavelet transforms. After that, energies of these components are calculated. As a result of these calculations, we have found that energy variations in high frequency bands are effective to calculate the P- and S-wave arrival times. P- and S-wave arrival times are determined using the frequency components with the highest energy level and first refraction directions in the interested window. In this study, 200 earthquakes with approximately 1000 real-time records were investigated using the proposed method.