International audienceThe existing knowledge about the recent crustal deformations along the Carmel Fault in Northern Israel which passes the city of Haifa is to a certain degree ambiguous. Depending on geological, geophysical or geodetic sources the movement rates and senses range from 1mm/yr sinistral up to 4mm/yr dextral. In this paper we analyze GPS data from a regional network observed between 1999 and 2009 and derive global and regional velocities for 23 sites along the fault. 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 and the horizontal velocity field shows deformations of up to 4.5mm/yr dextral. In combination with an S-transformation the site velocities were used to estimate the parameters of a dislocation model based on elastic half space theory. We compare the results with expectations from slip rate analysis of seismicity parameters. In addition the resulting fault slip field is used to derive a fault-related velocity field

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The Carmel Fault is one of the major geological structures of northern Israel. It is the northwestern part of Carmel-Tirtza Fault System and a northwestern branch of the Dead Sea Fault. The Carmel Fault region is covered by a monitoring geodetic network consisting of 23 sites, which were measured four times between 1999 and 2010 by means of GPS. The site velocities can be estimated only if the datum of the network has not been changed between measurement epochs. The GPS vectors must be adjusted so that the datum will remain undisturbed throughout the measurement campaigns. Usually we assume that GPS vectors define the network datum components of orientation and scale. Fluctuations in the GPS orbits could affect the orientation and scale between monitoring campaigns and therefore, in this study, we assume that GPS vectors are not immune to changes in their datum content. An appropriate approach is taken to prevent the inclusion of these components in the adjustment of a 4D network. If not, the result will be an inevitable mixture between the deformation parameters and the datum components of the GPS vectors. In this study the GPS vectors from each campaign are stripped from their datum content using the extended free network adjustment constraints. The datumless measurements are used to define the datum by preliminary coordinates and linear constraints, which remain constant for all monitoring campaigns, as well as to define the position of the network points and their velocities. Later on, the variations across the network geometry can be modeled by means of a physical model.