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In 2001, rock falls occurred on the southern slope of the Sumela Monastery, which was built on a cliff in Trabzon, north east Turkey, and is visited by many tourists. Considering the steepness of the slope and difficulty of access, rock classifications were made based on seismic wave velocity, rock mass quality ( Q), rock quality designation (RQD) and rock mass rating (RMR). The results indicated extremely poor to very poor rock in the cracked, fractured and weathered parts and poor to fair rock in the intact parts of the monastery slope. As a consequence, rock fall, slide and rolling may occur from time to time. These constitute a hazard to the facilities of the monastery and access paths. It is recommended that cracked areas are strengthened with cement-based materials, that accumulated rocks are removed, and that retaining walls are constructed on solid rock around the unstable rock blocks. [ABSTRACT FROM AUTHOR]

The Eastern Pontide orogenic belt is divided into three subzones (northern, southern and axial zones) based on present lithologies and facies associations. NE-SW-, NW-SE- and E-W-trending fault systems, which play an important role in palaeotectonics and neotectonics of the Eastern Pontides, separate these zones. Three different methods were used to estimate the Moho depth from observed gravity value, namely (i) empirical relationship between Moho depth and Bouguer anomaly: (ii) spectral analysis of the radial wave number and; (iii) by the gravity inversion method. Power spectrum, a statistical approach, is a widely used technique to determine the depth of geological sources successfully. The empirical linear relations between the Bouguer anomalies and seismically determined crustal thicknesses have been used to compute depths to the Conrad and Moho discontinuities, which are consistent with the average depths obtained from the power spectrum method. The crustal structure was also determined from the inversion of a Bouguer anomaly profile along longitude 39°. Gravity inversion results are consistent with those obtained from the empirical relations and power spectrum methods. We calculated the maximum crustal thickness of 43.8 km in the studied region by using the gravity inversion method, which also showed that crustal thickness increases from north to south. [ABSTRACT FROM AUTHOR]

Abstract Due to the burgeoning energy demand in Turkey, there has been a significant increase in the number of dams and hydroelectric power plants constructed; >250 dams have been built in the past 10 years. Consequently, various engineering problems were encountered due to landslides near reservoirs, both during and after the construction. Generally, two-dimensional (2D) and three-dimensional (3D) empirical equations have been used to calculate the physical properties and propagation of the landslide-induced impulse waves; however, 3D numerical simulation-based methodologies are rarely used, although they can model the complex geometry of dam reservoirs better, using detailed topographic data. In this study, therefore, 3D numerical analysis is carried out for a potential generation of impulse waves, using the data of paleo-landslide at the Artvin Dam reservoir (NE Turkey), and the results are compared with the calculated results by empirical equations. A finite element method-based shear strength reduction analysis (FEM-SSR) was performed to analyse the slope stability. After the establishment of the correct propagation model, the equations were utilised with different input parameters and 3D numerical analysis-based simulations to evaluate the characteristics of the impulse waves. In the numerical model created using the FLOW-3D software, the 'drift-flux model' was used to simulate the probable landslides. The Reynolds-averaged Navier–Stokes equations were used in a free-surface modelling technique together with the volume of fluid (VOF) model for simulating the wave generation. The renormalised group model (RNG) for viscous flow and k-ε turbulence model for fluid–fluid coupled condition, were used as the boundary conditions. The results indicated that the values obtained from the proposed empirical equations and 3D numerical analysis were not similar. Thus, if the reservoir geometry is very complex and the wave propagation distance is more than a few kilometers (as in this study), highly detailed engineering geological studies should be performed to accurately define the boundary conditions, and three-dimensional numerical analyses should be performed to construct the impulse wave model. Highlights • Landslide-induced impulse waves were modelled. • Empirical equations and 3D numerical analysis were used. • The empirical equations provided similar results as the numerical analysis. • Empirical results should be controlled using numerical models for complex reservoir geometry. [ABSTRACT FROM AUTHOR]

It is extremely important for regional tourism to determine the possible extensions of Karaca Cavern, one of the most important tourism destinations of the Gümüşhane province in Northeast Turkey. Cavities in karstic areas have been frequently revealed using geophysical surveys. This study tried to ascertain the spatial distribution and extension of the limestone cavern system using these techniques. In pursuit of this goal, ground-penetrating radar (GPR), electrical resistivity tomography and seismic tomography methods were performed close to the Karaca Cavern. Appropriate sites for geophysical measurement were selected within the investigation area. The GPR measurements were collected with 100 MHz centre frequency unshielded antennas on 15 profiles over the investigation area of 5,000 m. Furthermore, both electrical resistivity and seismic tomography data were acquired along with one profile on the site. All data sets were processed and interpreted to visualize the cave as well as the shallow subsurface structure of the site. As a result, it was found that a variety of hyperbolic reflections of different depths and sizes on the radargrams as well as low velocity and high resistivity areas with respect host rock observed in the seismic and resistivity tomography sections may indicate possible extensions of the Karaca Cavern. It has been suggested that locations of anomalies pinpointed using these methods could be opened at the sites. If these places are drilled, the cavern may be enlarged and its importance may increase in terms of tourism. [ABSTRACT FROM AUTHOR]

Seismic P- and S- wave velocities are directly dependent on the physical properties of the geological units (soil and rock) in which they propagate, the degree of decomposition and fracture-crack, depth and porosity, and are widely used in estimating the rippability in excavation works. P- and S-wave velocities of geological units can be determined by seismic refraction and multichannel surface wave analysis (MASW) methods, respectively, in the field. The rippability classes can be estimated quickly and reliably in relation to the distribution of the seismic velocities in 1 and 2 dimensions (1D and 2D) and geotechnical characteristics of geological units. In this study, data from many in situ seismic measurements performed in four different areas in vicinity of center of Trabzon province were re-evaluated using P- and S-wave velocity classification tables prepared according to international standards (Caterpillar and NEHRP) for the rippability of geological units in the measurement areas and a primary seismic velocityrippability-geotechnical classification table was prepared by including S-wave velocity. Therefore, the type (soil, rock) and mechanical property (firm, solid, hard, etc.) of the geological units are defined according to the S-wave velocity and the degree of rippability according to the P-wave velocity. Accordingly, in general, the geological units in the study areas are classified as very easy-to-easy, less firm soil (Vp <900 m/s, Vs <300 m/s), moderately rippabile solid- firm soil (Vp900-1500 m/s, Vs400-600 m/s), hard to rippabile very firm-solid or weathered rock (Vp1500-2100 m/s, Vs600-800 m/s), very hard-to-extremely hard to rippabile solid rock (Vp2100-2400 m/s, Vs800-1100 m/s) and non-rippabile hard rock (Vp>2400 m/s, Vs>1100 m/s). In addition, it has been shown that the approximate limits of geological units on 2D Pwave velocity-depth sections. Consequently, the evaluation of P- and Swave velocities together has provided the information about the type (soil or rock), mechanical and physical properties of the geological units besides the rippability, thus will ensure minimizing the rippability estimation errors and to the guiding of excavation works. [ABSTRACT FROM AUTHOR]