Thesis: The Alpine range is one of the first monitored mountain belts worldwide, both by seismic networks and space geodesy (GNSS), in particular due to its moderate but steady seismicity. Permanent GNSS measurements demonstrated that uplift is the main signal characterizing the current deformation in the European western Alps, reaching up to 2 mm/yr, while no shortening is observed across the belt. Based on the incredible amount of geodetic and seismic data available today, it now appears possible to constrain a new high resolution crustal strain field in the western Alps. This 3D field, made of surface deformation measurements and of the seismic deformation characteristics, is of primary importance in order to decipher the links between horizontal, vertical and seismic deformations. We rely for the present work on a multidisciplinary approach that aims at integrating 25 years long seismic records, 20 years of GPS measurements, and 4 years of Sentinel-1 satellite acquisitions, in order to establish the corresponding 3D strain rate field.For the first time in the western Alps, the spatial variability of the style of seismic deformation is robustly assessed, thanks to the analysis of the Sismalp (ISTerre Grenoble) database. New focal mechanisms computation along with principal stresses inversions have led to establish new orientations for the extensive deformation component, which occurs mainly in the center of the belt. As for the highly resolved 3D field of style of deformation, provided by Bayesian interpolations of focal mechanisms both at the surface and at depth, it reveals a vast majority of dextral strike-slip deformation occurring at the periphery of the belt, associated, in one specific area, with compression. These results bring new insights in the dynamics of the western alpine belt.Four GPS surveys (conducted in 1996, 2006, 2011 and 2016), along with the data provided by the permanent RENAG network, allowed us to increase the spatial resolution of the surface velocity and strain rate fields at the scale of the western Alps. These high resolution geodetic fields reveal that the amplitude of the extensive signal is at the highest in the Briançonnais area, while its kinematics appear consistent with interseismic deformation accommodated on at least one fault (the High Durance Fault). Longer-term seismic records show that, at least at the local scale, seismic and geodetic deformation patterns seem consistent within their uncertainty bounds in terms of kinematics and amplitude. At the regional scale of the entire western Alps though, geodetic strain rates appear one order of magnitude higher than the seismic ones, the latter comprising both instrumental and historical seismicity.Finally, four years of Sentinel-1 acquisitions appear to be the minimum time span required in order to derive long-term velocity maps in the satellite line of sight at the scale of the western Alps. The interferometric processing of the corresponding data allowed for the first time to get rid of the effects of snow and vegetation in a consistent way. The results feature short scale spatial variations in the uplift pattern, which are spatially correlated to crystalline external Alpine massifs as well as to the uplift patterns predicted by several isostatic adjustment models.This multidisciplinary work enabled us to increase the spatial resolution both of horizontal and vertical surface deformations and of seismic crustal deformation. The related 3D strain rate field sheds new lights on the various processes from which seismicity and deformation can originate. This 3D strain rate field moreover brings new constraints on several primary inputs to seismic hazard assessment models.