Clear P-wave arrival of weak events and automatic onset determination using wavelet filter banks

P-wave arrivals of many weak events cannot be precisely determined manually. Difference in power levels between noise and P-wave in wavelet detail of weak events enables us to determine P-wave arrival manually. Because of this power difference, automatic onset detection and picking algorithm is introduced using the same wavelet detail. Parameter settings are not needed as algorithm will work on data generated by either short or very broad band seismometers. Application of the proposed algorithm on data of three stations of Egyptian National Seismic Network (ENSN) in Cairo region shows a maximum standard deviation of 0.14 seconds of the corresponding manual picks.