Abstract: Although there has been no earthquake in the Gediz (Alaşehir) Graben since the 1969 Alaşehir earthquaketo cause a surface rupture, serious surface cracks and depressions occur between the Alaşehir and Sarıgöl area. Studies performed in the region have not reached a consensus on whether these deformations are due to tectoniceffects / groundwater level changes. Our research claims to evaluate the 2D vertical and horizontal velocity ratios obtained by using the PS-InSAR technique in the light of geological information and to establish the tectonic model that caused the deformation. Forthis, Sentinel-1 satellite images between 2015-2023 were used. Accordingly, the deformation rate in the hanging wall of the Sarıgöl Fault is -26 mm/y and +3 mm/y in the footwall. This means that under the tectonic regime, the Bozdağ Horst is uplifing while the graben is continuously collapsing. The Swath profiles clearly show that the graben border faults directly control the subsidence geometry of the basin. The fact that we obtained 11 mm/y (westward)and 7 mm/y (eastward) horizontal movements in opposite directions in the area of the maximum vertical deformation area indicates that the subsidence occurred with radial bulging in the horizontal plane and in a synformal geometry vertically. That is, the horizontal movement is related to the geometry and type of the southern border faults that directly control the subsidence regime of the basin, rather than the NW-SE directional compression in the region. In addition, the vertical deformations, which increase towards the southern margin and decrease towards the interior of the basin, point that the main graben fault with listric geometry may have been caused by a domino-style reversalin the hanging-wall. The fact that the deformations are not visible from the west of Alaşehir is due to the fact thatthe Alaşehir and Salihli sub-basins mentioned in the literature are limited by a covered semi-vertical fault. The observations of inconsistencies in vertical velocity and groundwater level changes at some points and the fact thatthese points are close to surface ruptures caused by the Alaşehir earthquake suggest that a significant part of the deformations occurred under tectonic effects. As a result, the deformations between Alaşehir and Sarıgöl occurred with a-seismic creep that occurred duringthe on going inter seismic phase, in addition to the seismic pulses that developed in the coseismic phase of the 1969 Alaşehir earthquake. Therefore, attributing current deformations to groundwater level changes alone may lead toerroneous modellings. Sudden changes in the groundwater level cause the a-seismic deformation that will occurduring the interseismic phase to accelerate the sediment consolidation developed under tectonic control and cause deformations to occur rapidly.