The study area is the Erzurum pull-apart basin located in the East Anatolian Tectonic Block (EATB), which is under the control of a strike-slip neotectonic regime since the beginning of Quaternary. The Quaternary Erzurum pull-apart basin is an about 1–30 km wide, 90 km long and actively growing strike-slip depression. It is bounded by the Erzurum–Dumlu sinistral strike-slip fault zone to the east-southeast, by the Askale sinistral strike-slip fault zone to the north-northwest, and by the Basköy–Kandilli reverse fault zone and the N–S-trending Ilica oblique-slip normal fault set to the west. The Erzurum pull-apart basin was evolved by the deformation and subdivision of an E–W-trending older intermontane basin. The new basin has a 0.5 km thick, flat-lying (undeformed) and uconsolidated fill, which overlies, with an angular unconformitry, the deformed (folded and faulted) basement rocks of pre-Quaternary age. Basin fill consists of coarser-grained marginal facies (fault terrace, fan, fan-apron and superimposed fan deposits) and finer-grained depocentral facies represented by flood plain to organic material-rich marsh deposits. All gradations are seen among these lithofacies. The seismicity of the Erzurum pull-apart basin is quite high. The magnitude of the peak earthquake to be sourced from the active faults (e.g., the Erzurum fault) is about Mw = 7.0. This was proved by both the historical and recent earthquakes. Numerous settlements in the size of a large city (e.g., Erzurum), county, town and small villages with a total population of over 766,000 are located in and along the active fault-bounded margins of the Erzurum pull-apart basin. They are under the threat of destructive earthquakes to be sourced from the margin-boundary faults. Therefore, based on both the active fault parameters and the water-saturated basin fill, a large-scale earthquake hazard map has to be prepared. This map has to be used in both the earthquake hazard to risk analyses and the redesign of city planning and all type of constructions in Erzurum and other settlements in this region.

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Rural projects become an important issue considering the rapid increase of population in Turkey. Alongside the contribution to the national economy, dams serve as an environmental structure, which are utilized in flood prevention, sustainable energy, fighting with forest fire and recreation. However, dam construction must be well planned and projected to minimize the unexpected events such as water leakage. This study comprise the geotechnical studies and the design of the planned grout curtain in Orhanlar Dam (Kütahya/Pazarlar). In this context, field and laboratory studies was realized in Orhanlar Dam axis and reservoir area. Within the scope of field studies, engineering geology map was generated, a suitable axis location was specified for the dam and drilling and in-situ testing was realized. Within the field studies, the joint conditions of the geological units under the dam axis and its effect on permeability was observed. For the geotechnical purposes drilling works performed during the planning stage, 5 boreholes total 166 m was realized on dam axis, 1 borehole total 10 m was realized on cofferdam, 1 borehole total 10 m was realized on diversion tunnel and 1 borehole total 10 m was realized on spillway. To determine the permeability profile on dam axis and design the grout curtain, Lugeon tests in Dağardı ophioloitic melange units observed in dam axis, falling head permeability tests in alluviums observed in thalveg and slope debris observed in right abutment were performed. As a result of these studies geotechnical information about the permeability of Orhanlar Dam was collected and the grout curtain hole was designed.

The electrical resistivity tomography method has been widely used in geophysics for many purposes such as determining geological structures, water movement, saltwater intrusion, and tectonic regime modeling. Karstic springs are important for water basin management since the karst systems are highly complex and vulnerable to exploitation and contamination. An accurate geophysical model of the subsurface is needed to reveal the spring structure. In this study, several karst springs in the Gökova Bay (SW, Turkey) were investigated to create a 3D subsurface model of the nearby karstic cavities utilizing electrical resistivity measurements. For this approach, 2D resistivity profiles were acquired and interpreted. Stratigraphically, colluvium, conglomerate, and dolomitic-limestone units were located in the field. The resistivity values of these formations were determined considering both the literature and field survey. Then, 2D profiles were interpolated to create a 3D resistivity model of the study area. Medium-large sized cavities were identified as well as their locations relative to the springs. The measured resistivities were also correlated with the corresponding geological units. The results were then used to construct a 3D model that aids to reveal the cavity geometry in the subsurface. Additionally, several faults are detected and their effect on the cavities is interpreted.

This study investigated the effects of active tectonism on the construction of hydraulic structures. Apart from the effect of dynamic loads, active tectonism can cause permeability problems. The focus of this study was on overcoming the permeability problems considering the economic yield in terms of grout curtain design and optimum dam axis location. The ground permeability of dam locations is one of the decisive factors affecting the feasibility and economic yield of dam construction. Techniques (such as grouting) for ensuring ground permeability reduction are generally expensive and time-consuming; the experience at the first location of the Turgutlu Dam is a case in point. Construction of the first location of Turgutlu Dam was planned on a fault terrace that is part of the North Anatolian Fault Zone, which is the most important active tectonic feature in Turkey. A grout curtain was planned to provide permeability reduction and ground treatment for the terrace material. However, the base elevation of the adjacent valley is deeper, and thus potential leakage to this valley was expected. In spite of its big reservoir area, the Turgutlu Dam Project became infeasible in terms of economic yield due to the ground remediation (construction of grout curtain) costs for this location. To solve this problem, the dam was relocated downstream to avoid the fault terrace, choosing an optimum grout curtain to minimize cost and improve water retention of the reservoir, and increase economic yield of the dam.