DETERMINATION OF VERTICAL CRUSTAL MOVEMENTS IN TEHRAN NORTH FAULT BY GPS-LEVELLING DATA

Integration of the global positioning system (GPS) and precise levelling has been proposed as the optimum method for determination of vertical crustal movements analysis. For the monitoring purposes, precise levelling is of low efficiency in terms of costs and observation speed. GPS technology provides fast, convenient and low cost approach which is comparable in accuracy to precise levelling. According to this study, the mean speed of subsidence in the area of Tehran north fault between 1997 to 1998 based on integration of GPS and precise levelling is 18.4 (mm) and root mean square value based on precise levlling and integrated model is 7.7 and 8.6, respectively. From the result, we can conclude that the GPS-levelling is suitable replacement for precise levelling in the vertical crustal movements studies.