An-Najah Staff

 To study the shallowest part of the crust spanning the Dead Sea transform fault (DSF), in the Dead Sea rift valley, tomographic inversion techniques were applied to first-arrival travel times of direct P-waves generated by vibrating trucks. The line was 100 km long,was oriented approximately perpendicular to the DSF (WNW-ESE), and was centered on the DSF. Vibroseis spread length was 18 km. Travel times(250,000) were picked manually for 1700 shots and 180 receivers. The 2-D version of FAST by Zelt and Bartov (1998) was used for the tomographic inversion. Since the inversion is non-unique, extensive testing of model and inversion parameters was carried out. By varying model parameters(block size and shape) and inversion parameters (number of iterations,vertical and horizontal smoothing parameters, choice of reasonable starting models), a stable final velocity model was found. Checkerboard tests indicate that P-wave velocity structure is well resolved down to a depth of several kilometers. The final veloc