Modeling of bedrock topography of edremit (Balikesir) basin using vertical electrical sounding (VES) and microgravity data

This thesis aims to determine the bedrock basement topography of the Edremit Gulf and its surrounding area in Balıkesir Province using microgravity and Vertical Electrical Sounding (VES) methods. The microgravity data were acquired within the scope of the TÜBİTAK project titled "Determination of Local Site Effects and Site-Specific Seismic Hazard and Dynamic Soil Behavior Analyses of the Edremit Plain (Balıkesir) and Its Surroundings" (Project No: 123Y151). The VES data were obtained using the Schlumberger electrode array as part of the General Directorate of Mineral Research and Exploration (MTA) project entitled "Preparation of Regional Geoelectrical Maps of Balıkesir–Çanakkale–İzmir, Turkey." VES measurements were collected at a total of 31 stations, and E, F, and G profiles were constructed. The re-evaluated data were interpreted using one-dimensional inversion to generate structural sections representing the geoelectrical basement surface. Microgravity measurements were carried out at 273 stations throughout the Edremit Basin and its surroundings. Bouguer gravity anomaly maps derived from these data were subjected to various filtering and derivative-based boundary analysis techniques. Additionally, the bedrock topography was reconstructed using 2.5D Talwani gravity modeling, and the results were compared with the structural sections obtained from the VES data. The step-like normal faults identified along the profiles indicate that the basin floor is controlled by a multi-segmented and multi-level fault system rather than a single master fault. These structural features are consistent with low-gravity zones observed on Bouguer anomaly maps and with the 2.5D Talwani modeling results, demonstrating that gravity and electrical resistivity methods provide complementary insights into basin geometry.