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Tectonic activity and crustal deformation in northern Israel are mainly related to the Dead Sea Fault (DSF) and the Carmel–Gilboa Fault System (CGFS). The CGFS is composed of several NW–SE trending faults while the main faults are the Carmel Fault (CF) and Gilboa Fault (GF). The CGFS divides the Sinai Sub-Plate into two tectonic domains. In this study, we geodetically investigate surface deformation processes in the Carmel Fault region. Beside the processing and analysis of GPS measurements, we highlight geodetic aspects in the process of deformation analysis in geodetic monitoring networks. We implement the Extended Free Network Adjustment Constraints solution to calculate the velocities of 24 sites that were measured eight times between 1999 and 2016 using Global Positioning System (GPS). The regional site velocities were estimated with respect to a local datum that was defined by a stable cluster of sites on one side of the fault. We introduced the site velocities into the estimation of surface deformation parameters by using affine transformation also with respect to a local datum. The coordinates of network sites can be transformed to any desired datum by using extended similarity transformation. Examination of the velocity field in relation to a datum defined by points in the Galilee region raises the suggestion that the velocities in the Yizre'el Valley region are due to activities along the GF or similar trending faults on the northern side of the valley which are halted by the Tivon Hills. The best set of deformation parameters, the one which better describes the velocity field, was determined by the second-order Akaike Information Criterion (AICc). The results show significant sinistral deformations of less than 1 mm/year along the Carmel Fault accompanied with extensions and shear strain. [ABSTRACT FROM AUTHOR]