In recent years there were several earthquakes in Turkey with magnitudes 7.4, 7.2 and 6 in Kocaeli, Duzce and Pulumur respectively. The first two occurred in 1999 causing the most damage both structurally and economically. The last happened in January 2003. These were all on the North Anatolian Fault and the earthquake occurrence was propagating towards east on the fault. Damage due to surface faulting, slope stability, liquefaction occurred during these earthquakes. In this paper the strong motion data acquired from these earthquakes at various locations are inspected using both the commonly used Fast Fourier transform and more recent harmonic wavelet analysis developed at Cambridge. Harmonic wavelet analysis is applied to some of the strong motion data obtained to observe the variation of frequency contents with time as the earthquake proceeds. With this analysis a comparison of the accelerations on the same fault was obtained. All the earthquakes had their strongest component in east-west direction and this could be seen with peak accelerations occurring in that direction. The contribution from different frequencies at different time instants to the energy of the signal was observed with the wavelet analysis and energy changes in each of the earthquakes could be seen
