Reza Mansoori

There are many destructive earthquakearound the world every day. The true and accurate estimation of the magnitude and focal mechanism of earthquakes in the early moment of P arrival time. Before intensive and destructive strong ground motions, is the key problem in early warning system, such systems are the acceptable tools for reducing financial and human causalities. The spectral analysis is important in magnitude studies. The wavelet transform is a powerful tool for spectral analysis in seismology. This transform covers the deficiency of Fourier Transform. In this research we used the time-frequency properties of the wavelet transform in order to study of the magnitude and focal mechanism. Through this study, we divide the magnitude studies using wavelet transform into two chapters; first we apply the transform to the 3, 5 and S-P seconds of the synthetic and read waveform and the second we study the magnitude versus distance and Azimuth the results show that the magnitude and the radiation pattern can be easily extracted. While we applied the method, the maximum wavelet coefficients are nonlinear till 2000 km. But beyond this distance the coefficients are linear versus distance .the coefficients are increased by increasing in magnitude. Also the distribution of wavelet coefficients versus azimuth demonstrate the radiation pattern of synthetic and real earthquakes. Finally, combining the radiation pattern of double couple and applying the proposed methodwe could estimate with accuracy of 80%.