Use of Land Gravity Data in Small Areas to Support Structural Geology, a Case Study in Eskişehir Basin, Turkey

Abstract

Various researchers have contributed to the literature on the locations and lengths of existing faults in the Eskişehir Basin, Turkey. However, the majority of the literature on the subject bases its results on fault indications observed on the surface, for example, surface ruptures. In addition, studies using geophysical methods in order to reveal buried faults have also fallen short regarding depth compared to gravity. In order to have a better understanding, the gravity method was applied with a total of 448 gravity measurements on five parallel lines in the north–south direction of the study area, which also includes the urban area of the Eskişehir Basin. Considering the neotectonics of the Eskişehir basin, the measurement lines were chosen to perpendicularly cut the east–west extending faults of the Eskişehir fault zone. For the first time in the literature, a detailed Bouguer gravity anomaly map has been obtained for the Eskişehir Basin using land gravity measurements. The edge detection Horizontal Gradient Magnitude (HGM) and Euler Deconvolution (ED) methods were applied to obtained Bouguer anomaly data. Both of these use spatial analysis of Bouguer gravity anomalies. An HGM map shows the presence of maximum amplitude areas in the south and north of the study, and these areas were found to be compatible with the known faults in the literature. ED solutions also support HGM maximums. The relationship between the lineaments obtained from the edge detections and the seismicity of the region were examined. It can be seen that the results obtained from both the HGM and ED edge detection methods are highly compatible with each other, and highly related to the structural geology of the region. Although great agreement with the faults in the literature was determined by both methods, only the ED method showed a number of newly found faults in the area. In addition, the locations of the known faults in the region were supported by the geo-physical gravity method for the first time.