Interpretation of higher mode Love waves at TBZ

We use broad-band seismograms to model the shear wave propagation of higher modes of Lg type under Anatolian crust. The modelling suffers numerical instabilities at high frequencies. The computation time is very high. Computer programs written is so design to alleviate the numerical instabilities, and Filon's method is used to reduce the computational time. Reflectivity method which models both upgoing and downgoing waves is utilized. The seismicity of right lateral north and left lateral east Anatolian strike slip faults are usually shallow around 10-15 km. Small and moderate size earthquakes with high frequency shear wave propagations are observed. We use one dimensional velocity profiles formerly published in the literature and extend them as necessary due to the lateral hetorogenity. In the first 15 km depth range SH velocity gradient is high, rising from 2.7 to 3.6 km/sec. This depth range controls the Lg velocity of 3.4 km/sec and shows a group velocity stationary phase. Another velocity gradient lower than the first appears to start from about 25 km depth and below that moho shows a smooth transition of thickness about 5 km at around 35 km in depth. This velocity profile results the Lg propagation for focal depths as deep as moho, but the frequency content is reduced as the focal depth increases. It is sometimes possible to observe the source time complexity looking at Lg waves of several band-pass filtered forms.Key Words : Broad-band seismograms, Computation time, Filon' s method Reflectivity method, Source time complexity.