Search

Uzungöl settlement and Lake Uzungöl are located in the south of Çaykara, Trabzon, Eastern Black Sea region, and are an important tourist destination in Turkey, with natural beauty and rich flora. However, the settlement and the lake were formed by a historical landslide that covered the front of the Haldizen stream. Residential buildings, tourist facilities, transportation routes, and agricultural activities are located on ground that consists of the material that accumulated from the landslide. In this study, a geophysical investigation using integrated shallow seismic methods was carried out in Uzungöl settlement to provide detailed scientific imaging data on the structure of the subsurface, the physical properties of the soil and rock, the bedrock topography, and the vertical and lateral variation in the landslide deposits. For this purpose, seismic refraction and active and passive multichannel surface wave data were collected from 16 profiles in four separate zones designated according to the agricultural activity and geomorphology of the area. In addition, an electrical resistivity tomography survey of a profile was carried out to determine the reason for low-velocity anomalies such as cavities or man-made voids appearing in P-wave velocity–depth sections and underground water content. After applying basic processes including trace killing/editing, random noise filtering of the data, and amplitude balancing to all seismic data, 2D P-wave velocity–depth sections obtained by tomographic inversion, 1D S-wave velocity–depth profiles, and 2D S-wave velocity–depth sections were generated via analysis of MASW and ReMi data. P- and S-wave velocity–depth sections generally demonstrate three main lithological units in the area: the soil (Vp = 300–600 m/s, Vs = 195–350 m/s and H = 0–2.5 m), the landslide material (Vp = 600–2400 m/s, Vs = 350–680 m/s and H = 2.5–15 m), and the bedrock (Vp > 2400 m/s, Vs > 680 m/s and H ≥ 15 m). In particular, the landslide material exhibits variable thickness from profile to profile and represents the complexity of the subsurface. However, we observed that the deposit thickness increases close to the lake. It was determined that the high seismic velocities of the landslide deposits are attributable to the densely packed deposits and the primarily dry or very poor underground water, according to electrical resistivity tomography results. Moreover, the top of the bedrock is characterized by soft rock, and the deeper part of the bedrock is harder and more compact. We believe that this information will be a useful contribution to geotechnical project development and risk mitigation in the Uzungöl area. [ABSTRACT FROM AUTHOR]

In this study, density, porosity, void ratio, and ultrasonic P- and S-wave first arrival times were measured on limestone, sandstone, and siltstone samples obtained by using mechanical soundings in the city of Zonguldak. Turkey. Fracture and fissure indexes of rocks were calculated from ultrasonic P- (Vp) and S-wave (Vs) velocities. Multi-parameter relationships occurred between ultrasonic velocities with seismic fracture and fissure indexes and physical and mechanical properties of the rocks. Root mean squared error (RMSE = 0.5–0.8%) values correlated between measured densities and densities calculated from Vp and Vs. The correlation coefficients of experimental relations between densities, void ratio, and porosity with seismic velocities that were obtained ranged from 78, 86, 67, and 84%, respectively. Consequently, natural, water-saturated and grain densities, porosity, and void ratio values were determined from new multi-parameter relationships obtained from the combined use of Vp and Vs. In addition, the results of this study suggest that the rock quality may wrongly be determined using the only Vp, whereas it can be obtained more accurately by using Vp and Vs together. The reason for this is that the P wave spreads in solid, liquid, and gas media, while the S-wave spreads only in solid media. Therefore, S-waves will not be altered by fracture filling (gas or liquid), while P-waves are affected by fracture filling. In the present study, the use of Vp and Vs together in relationships was more useful in determining the strength and hydraulic properties of rock mass that the use of either Vp or Vs alone. Also, Rock Quality Designation (RQD) and Rock Mass Rating (RMR) values can be correctly calculated from the combined use of Vp and Vs. As a result, interpretation of crack fill and classification of the rocks can be quickly performed using seismic velocities. [ABSTRACT FROM AUTHOR]

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]

For Anatolian earthquakes, there are insufficient strong motion data from rock sites to model an attenuation relationship for Turkey. This necessitates the use of records from soil sites, which are significantly affected by amplification. In order to include soil site data in the attenuation analyses, boreholes were drilled at 64 recording stations on soil sites. After removing the effects of soil amplification, rock site and soil site data were combined to establish an attenuation relationship. Various models were tested through regression analyses using moment magnitude, epicentral distance and threshold peak horizontal ground acceleration. A new attenuation relationship is modeled for Turkey. [ABSTRACT FROM AUTHOR]