Determination of crust deformations with precise levelling technique: A case of Sarigöl

In order to reduce or minimize the impacts of earthquakes, it is necessary to examine the plate movements causing the earthquakes. For this reason, the center of Sarigol and its surroundings have been examined since this region contains earthquake risks. The 1969 earthquake in the past is the biggest example of this. The vertical deformations started in 1996 within the borders of Sarıgöl district has been observed with leveling technique. These leveling lines consist of 2 profiles perpendicular to the deformations. Up to date, no detailed geodetic studies have been carried out in the eastern part of Gediz Graben. Since the seismic activity and surface deformations of this region continue to increase, there is a need for a precise leveling technique that can achieve precise results. The region, which is affected by deformation as a result of tectonic movements, located in the study area has been monitoried using GNSS method. In addition to the GNSS method for measuring deformations in this region, a precise leveling technique should be used to obtain more accurate results, vertically. A leveling network has been established to determine surface deformations. This leveling network consists of 14 reference points. The measurements were carried out as 7 campaigns between 2017 and 2019. As a result of 1.5 years of measurements made with precision leveling technique, very reliable vigorous and precise results were obtained. The leveling measurements showed that vertical deformations have been formed between -100 and -120 mm in approximately 20 months. It was attempted to carry out leveling measurements in approximately every season. According to these results, there is an increase in the amount of deformations especially in the summer and autumn months; it can be stated that the deformations could be associated with the groundwater. Agricultural irrigation in the region causes the ground water level to drop during the summer months. This can be seen as the cause of the increase in the amount of deformation during the summer months. Despite the fact that there is an increase in the groundwater levels with the heavy rainfall in the winter and spring months, the continuation of the deformations gave the idea that the tectonic creep movements may be the origin of the deformations.