Granit kökenli farklı litolojik birimler içeren Eosen yaşlı Sarıçiçek (Gümüşhane) ve Sarıhan (Bayburt) Plütonları üzerinde 532 noktada yerinde radyoaktivite ve manyetik suseptibilite ölçümleri yapılmıştır. Her iki plüton ve çevresindeki kayaçlardan numuneler alınarak laboratuvar ortamında bu kayaçların yoğunlukları belirlenmiştir. Yapılan çalışmada hem granitik kayaçların ısı üretimine olan katkıları ile ısı değerine bağlı kabuk sınıflaması hem de kayaçların radyojenik ısı üretimi ve manyetik suseptibiliteleri arasında bir ilişkinin olup olmadığı araştırılmıştır. Radyojenik ısı üretim değerine göre yapılan kabuk sınıflamasında; üst-alt kıtasal kabuk kökenli kayaçlardan oluşan Eosen yaşlı Sarıhan Plütonunun ortalama radyojenik ısı değeri (2.03 µW/m3), üst-orta kıtasal kabuk kökenli kayaçlardan oluşan Eosen yaşlı Sarıçiçek Plütonunun değerinden (1.9 µW/m3) yüksektir. Plüton, Melanj kuşağı ve Hozbirikyayla formasyonları için ortalama suseptibilite değerleri sırasıyla 1.08×10-3 SI, 0.132×10-3 SI ve 0.059×10-3 SI olarak hesaplanmıştır. Ortalama suseptibilite değerleri Sarıçiçek Plütonu için 1.518×10-3 SI ve Alibaba formasyonu için 2.5012×10-3 SI olarak belirlenmiştir. Çalışma alanındaki radyoaktif ölçümlere göre Sarıçiçek Plütonunda radyojenik ısı üretimine en büyük katkı potasyumdan (K) gelirken, Sarıhan Plütonunda ise en büyük katkıyı toryum (Th) radyonüklidi sağlamıştır. Sarıçiçek ve Sarıhan Plütonunları ve çevre formasyonların radyojenik ısı üretim değerleri ile manyetik suseptibilite değerleri arasında genel olarak bir uyum söz konusu iken, kayaçların içerdiği mineral ve element içeriklerine bağlı olarak uyumsuzluklar da gözlenmiştir. Uyumsuzluklar, magmatizma ve sonrasındaki süreçlerden dolayı radyonüklid miktarlarında ve mineral içeriklerinde meydana gelen düzensiz değişimlerle ilişkilendirilmiştir.

The radionuclide concentrations of eU (ppm), eTh (ppm), K (%) and dose rate values were measured in Sarıçiçek (Gümüşhane) and Sarıhan (Bayburt) granodiorites for a duration of 5 minutes at each of 532 measurement points. The radioelement ratios (eU/eTh, eU/K, and eTh/K) indicating the origins of the rocks, the geochemical indicators (Ume, F parameter, and eU-(eTh/3,5) rate) showing the uranium mobility and the radioelement concentrations were calculated and mapped within the study areas. The average K, eU, and eTh concentrations were calculated as 2.98%, 3.15 ppm, and 12.45 ppm for Sarıçiçek granodiorite, and 1.83%, 2.73 ppm, and 13.6 ppm for Sarıhan granodiorite, respectively. Higher radioactivity values were observed in basaltic, sedimentary, and ultramafic rock combinations within the granodiorite masses. In the classification according to radioelement ratios, it was concluded that the rocks in the study areas formed as a mixture of upper mantle and crustal materials. In both study areas, there was uranium transport from the granodioritic masses into the surrounding rocks, and accordingly, the rocks in the surrounding formations were enriched in uranium. As a result, radioactivity levels, rock formation origins, and uranium transport of both granodioritic masses and rocks in the surrounding formations were determined by evaluation with radioelement concentration values and ratios and migration parameters. The study areas were characterized by associating them with geology in light of radioactive data.

In situ radioactivity measurements were performed to describe and map the relationship between the radioactive concentration distribution on the surface and geological formations in the Karadeniz Technical University (KTU) campus and surrounding area located on the shore of the Black Sea in NE Turkey. The concentrations of radio-elements (eU, eTh, and K) and dose rate values were measured using a portable gamma-ray spectrometer with NaI(Tl) crystal at 150 points in the study area with a duration of 5 min for each measurement point. In addition, the geochemical radio-element ratios (eTh/eU, K/eU, and eU/eTh) give information about the origin of the rocks, and radiological hazard parameters for humans and the environment were also calculated. Average values of eU, eTh, and K concentrations, and dose rate, were calculated to be 3.59 ppm, 13.46 ppm, 0.84%, and 65.38 nGy/h, respectively. While the highest concentrations of radio-element and dose rate values were recorded at outcrops of Eocene-Neogene basaltic rocks and red clays, which are the weathering product of the Kabaköy formation, the lower anomaly zones coincide with brown and reddish brown forest and agricultural soils of volcanic origin in the study area. According to the average radio-element ratios, it was concluded that the rocks in the study area do not completely originate from the crust, but formed as a result of the mixture of upper mantle and continental crust. All the calculated hazard parameters seem to be lower than the internationally recommended values, and there is no cancer risk in and around the campus area.

In this paper, the lithospheric structure underneath the Circum Black Sea is investigated on the basis of teleseismic receiver functions and Rayleigh wave phase velocity analyses. A joint inversion of P- and S-wave receiver functions are performed by using an iterative algorithm, similar to the simulated annealing method. The array method is employed to obtain the Rayleigh wave inter-station phase velocity dispersion curves. The dataset recorded during 2010-2020 by sixteen broadband stations, operated by several seismological agencies, includes more than 450 events (Mw >= 5.8). The Moho depth increases northward from 35 km to 40 km along both coastlines. Following the velocity models, it is suggested that the crust structure beneath the stations is the continental type. The lithosphere-asthenosphere boundary ranges from similar to 90 km to similar to 120 km from the east coast of the East Black Sea basin, while it is low-sloping (from similar to 100 km to similar to 93 km) for the west coast of the West Black Sea basin, and it is nearly 90 km along with the Pontides. The average P-wave and S-wave velocities inferred from the models indicate the continental lithosphere around the Black Sea coastal region. According to these results, tectonically, it points out that the southward subduction exists in the eastern part of the East Black Sea region beneath the Pontides, while it is not observed in the westernmost Black Sea region.

The article Lake Van (Southeastern Turkey) Experiment.

Summary This study will supply an overview of crust and upper mantle structure beneath the Lake Van region based on the Receiver Function analyses of P- and S- waves using the teleseismic data set taken from the European Integrated Data Archive. All inversion results will depict the present day tectonics of the Lake Van region. Also, spatial variations of the b-values are calculated by using data covers all earthquakes occurred between 1900-2017. The b-values will inform us about the compatibility between the seismic regime and seismic velocity for the depth from near surface to 30 km.

In this study, we use teleseismic P and S receiver functions (i.e., S-to-P and P-to-S converted signals) and their joint inversions to determine seismic discontinuities in the crust and upper mantle. Eight permanent broadband stations from the KOERI (Kandilli Observatory and Earthquake Research Institute) that are distributed along the eastern Pontides orogenic belt (EPOB), NE, Turkey, comprise our database. Inversion is performed by using a simulated annealing technique with and without travel time residuals. Our inversion results reveal the Moho depth, a high S velocity lid, a low-velocity zone, and the underlying upper mantle layer. The studied area is divided into two regions based on the station locations: (a) a northern region and (b) a southern region. The inversion results from the northern area produce crustal models that indicate that the uppermost crust is represented by a low P and S wave velocity (Vp = ~ 5.0 km/s and Vs = ~ 2.8 km/s). These velocities are clear evidence of (1) the sedimentary and volcanic rocks that widely crop out in the region and (2) a thinner uppermost crust, whereas the velocities of the southern region (Vp = ~ 6.0 km/s and Vs = ~ 3.1 km/s) indicate a thicker uppermost crust (~ 7 km). Our calculated Vp/Vs velocity ratio in the lower crust is approximately 1.90 and 1.80 in the northern and southern regions, respectively. These ratios are generally attributed to mafic rocks. Beneath the northern stations, the crustal thicknesses are 30, 33, 37, and 40 km from east to west, while the depths of the Moho are 46, 42, 39, and 44 km beneath the southern stations. Some velocity histograms show a transition from the high S velocity mantle lid to the low-velocity zone, which is known as the lithosphere–asthenosphere boundary. A representative value of the boundary’s depth is around 83 km in the north and ~ 88 km in the south. The hypothesis of some researchers regarding the existence of southward subduction beneath the eastern Pontides orogenic belt during the Late Mesozoic–Cenozoic is supported by our 2-D and 3-D velocity-depth models.

Bu calismada, Van Golu Havzasi’nda bulunan Kandilli Rasathanesi ve Deprem Arastirma Enstiusu tarafindan isletilen AKDM ve MLAZ genis-bantli deprem istasyonlarinin verileri kullanilarak, P- ve S-Alici Fonksiyonlarinin Birlesik Ters Cozumu’nden P- ve S-dalgasi hiz histogramlari elde edilmistir. Ps donusum fazlari derinlik-yigma sonuclarinda ve Sp donusum fazlari da yavaslik-yigma sonuclarinda belirlenmistir. Birlesik ters cozum sonuclarina gore, alt kabukta ortalama S dalgasi hizlari, P dalgasi hizlari ve Vp/Vs orani sirasiyla ortalama 3.6 km/sn, 6.3 km/sn ve 1.80’ dir. Dusuk hizlar, bolgedeki yaygin volkanizma ve Vp/Vs orani ise mafik kayaclar ile iliskilendirilebilir. MLAZ istasyonu icin elde edilen kabuk kalinligi yaklasik olarak 42 km iken (Vs 3.6 km/sn’ den 4.3 km/s’ ye ve Vp 6.3 km/sn’ den 7.9 km/s’ ye artmaktadir), AKDM istasyonu icin elde edilen kabuk kalinligi 39 km’ dir (Vs 3.7 km/sn’ den 4.1 km/s’ ye ve Vp 6.4 km/sn’ den 8.1 km/s’ ye artmaktadir). Ust mantoda ~90 km’ ye kadar S-dalgasi hizi oldukca dusuk olarak elde edilmistir. Sonuc olarak, ust manto hizlari sicak, sig astenosferik materyalden dolayi dusuktur.

This study focuses on the average crustal and the upper mantle structure throughout the Lake Van region of eastern Turkey. The study aimed to investigate the structure with the fundamental mode interstation Rayleigh wave phase velocities from the local and the regional earthquakes recorded by Kandilli Observatory and Earthquake Research Institute stations. Considering back azimuth differences of each source and station path, six different broadband station pairs and 27 earthquakes were selected to determine the 1-D shear-wave velocity structures throughout the region by using an interstation method (slant stacking technique). The linearized least squares algorithm was used to obtain the 1-D shear-velocity model that best fit the observed phase velocity dispersion curve. The normalized statistical resolution matrix was calculated to measure the reliability of the solution. Inversion results revealed that the solution quality of the upper crust is weak due to the high resolution lengths. The average shear-wave velocities in the lower crust scale down to approximately 3.5 km/s. It was inferred that this low-velocity zone shown in the lower crust may be associated with widespread volcanism. Final 2-D S-wave velocity models obtained from the inversion revealed that the crust-mantle boundary is similar to 42 km, and shear velocities vary from 3.6 to 4.2 km/s. Furthermore, the upper mantle (similar to 45-70 km) velocities are slower than globally suggested models (e. g., IASP91), and this is possibly related to shallow hot asthenospheric material.

The present work utilizes in situ gamma ray spectrometric measurement data to map the surface geology of Sarıhan Granitoid and its surrounding area. The study area comprises three different lithological units, namely, Hozbirikyayla Formation (limestone and sandy limestones), Sarıhan Granitoid (consist of quartz monzodiorite, granodiorite and quartz diorite) and the Ophiolitic olistostromal melange (andesite, basalt, sandstone, gravelly sandstone). When lithological units are assessed according to the radioactivity characteristics, natural radionuclide contents (40K and radionuclides from 238U and 232Th series) of Hozbirikyayla limestones and ophiolitic melange rocks are lower than the Sarıhan pluton. The U, Th and K radionuclide contents were found to be 0.8–5.4 ppm, 10.1–33.6 ppm and 1.29–4.41% in the Sarıhan plutonic area and 0.9–5.3 ppm, 1.1–20.3 ppm and 0.04–2.71% in Horzbirikyayla formation, respectively. The element concentrations of 238U, 232Th and 40K of the Ophiolitic melange are 1.1–4.5 ppm, 1.6–25.3 ppm and 0.09–3.63%, respectively. Radioelement ratio maps are created for the studied area, because the parameters of radioelement ratios, eU/eTh, eU/K and eTh/K, reflect the radioactive characters of the rock and soil. The Hozbirikyayla Formation is characterized by the highest value of eU/eTh and lowest value of eTh/K. While the lowest eU/eTh and eU/K ratios were observed in the Sarıhan Granodiorite, the highest value of eU/K and eTh/K were obtained in the Ophiolitic olistostromal melange. By comparing these maps with the geology, it was found that the radioelement concentrations are in good agreement with the geological properties of the region. In addition to this, the radiation hazard parameters were evaluated to assess the radiation hazard for people living in this area. It has also been found that there is no significant radiologic hazard for humans and the environment in and around studied area.

Summary To better understand the deep structure of the Eastern Pontides orogenic belt (NE Turkey), we have just analyzed the teleseismic-records of the KTUT station as an initial study. For this purpose, P and S Receiver Functions are calculated, and then inverted jointly together with teleseismic P and S traveltime residuals. The inversion is performed using a simulated annealing technique. No high-quality signal is observed at the KTUT station for the Ps converted phase from P410s and P660s km discontinuity. An early arrival is observed at this station for P410s which is ∼0.5 s than the IASP91 global model. The crust has a thickness of about 34 km, and the high-S-velocity mantle lid is beneath the crust at a depth of about 65 km. The velocities of Vs and Vp in the crust are close to Vs= ∼3.61 km/s and Vp= ∼6.37 km/s, respectively. The S wave velocity decreases to ∼4.22 km/s at the low-S-velocity zone beneath the crust, and it reaches to ∼4.65 km/s at upper mantle. Consequently, the crust and upper mantle thicknesses derived from the receiver functions analyses are in good agreement with results from other studies.

In this study, the crustal S-wave structure beneath the Eastern Black Sea Region (including the Eastern Black Sea Basin (EBSB) and Eastern Pontides (EP)) has been revealed using inversion of single-station, fundamental-mode Rayleigh-wave group velocities in the period range of 4-40 seconds. We used digital broadband recordings of 13 regional earthquakes that recently occurred in the easternmost EBSB recorded at stations of the Kandilli Observatory and Earthquake Research Institute (KOERI). The average group-velocity-dispersion curves were generated from 26 paths for the EBSB, and 16 paths for the EP, and they were inverted to determine the average 1-D shear-wave structure of the region. We have created a pseudo-section, roughly depicting the crustal structure of the region based on the group velocity inversion results of all station-earthquake paths. The thickness of the sedimentary layer reaches 12 km in the center of EBSB (V-S= 2.5-3.1 km/s) and decreases 4 km in the EP. There is a thin sedimentary layer in the EP (V-S = 2.7 km/s). A consolidated thin crust that exists in the EBSB possesses a high seismic velocity (V-S = 3.8 km/s). While a thin (similar to 26 km) and transitional crust exists beneath the EBSB, a thick (about 42 km) continental crust exists beneath the EP where the Conrad is clearly seen at about a 24 km depth. Thick continental crust in the EP region is clearly distinguished from a gradational velocity change (V-S = 3.4-3.8 km/s). The Moho dips approximately southwards, and the V-S velocity (4.25-4.15 km/s) beneath the Moho discontinuity decreases from the EBSB to the EP in the N-S direction. This may be an indication of a southward subduction. (c) 2015 Elsevier Ltd. All rights reserved.

Summary Environmental radioactivity level of the former Trabzon municipal solid waste dumpsite were investigated by in-situ gamma-ray spectrometric method. The natural radioelement concentrations on the surface of dumpsite were measured using a portable gamma-ray spectrometer. Spectrometry data were collected on the ground surface at 231 points along 21 profiles, parallel to each other, where the interval for both measurement points and each profile are 10 m. The measuring time was set to be 300 s at each point. The average activity concentrations of 238U, 232Th, 40K and dose rate in the dumpsite are 42.68 Bq/kg, 49.88 Bq/kg, 417 Bq/kg, and 67.91 nGy/h respectively. In addition, radiation hazard parameters were calculated and compared with the international standard values. Consequently, it was found that there is no significant radiologic hazard and risk for humans and the environment in studied area.

Indoor gamma radiation dose rate and natural radionuclide concentrations ( 238 U, 232 Th, and 40 K) are measured inside former Geoscience Faculty Buildings of Karadeniz Technical University in Trabzon using a 512-channel portable gamma-ray spectrometer with a sodium iodide during the six-month period. Spectrometry data are collected on all floors for each building. The average radionuclide concentrations of 238 U, 232 Th, 40 K and dose rate in the buildings are 4.07 ppm, 11.58 ppm, % 1.98 and 79.03 nGy/h for Dean Building, 4.81 ppm, 13.38 ppm, % 2.52 and 94.2 nGy/h for Geophysical Engineering Building, 4.03 ppm, 13.14 ppm, %2.59 and 89.99 nGy/h for Geology Engineering Building, 3.76 ppm, 14.15 ppm, %2.68 and 92.34 nGy/h for Geomatics Engineering Building, respectively. In addition to this, the radiation hazard parameters (absorbed dose in the air, radium equivalent activity, internal hazard index and annual effective dose equivalent) for indoor environment are calculated and then jointly interpreted in order to find out the whether a radiological hazard exists in these buildings. As the result from this study, there is no significant radiologic hazard for human in studied buildings.

Summary The concentrations of equivalent eU, eTh, K% and dose rate values were measured using in-situ gamma-ray survey in order to map rapidly the surface geology of the Sarıçiçek pluton and its surrounding area. Gamma-ray spectrometric data were collected with a 512-channel portable gamma-ray spectrometer (NaI (Tl) cyrstal) at 265 points in which duration for a single point measurement is 5 minutes. The average activity concentrations of 238U, 232Th, 40K and dose rate obtained in this study are 38.97 Bq/kg, 50.56 Bq/kg, 935.267Bq/kg and 88.78 nGy/h, respectively. Although distinct radioactive anomalies were found in the studied area, the radiometric values showed some minor variations with slightly higher values than the normal level. As the result of this study, the average values of the absorbed gamma dose rate in air, radium equivalent activity, annual effective dose rate and the external hazard index were also calculated and examined in terms of radiologic hazard in this area. Consequently, all of the radiometric parameters are in good agreement with the regional surface geology of the Sarıçiçek pluton and its surrounding formation and there is no significant radiologic risk for humans and environment in and around this area.

Radionuclide variations, the vertical and lateral extent of a waste mass in the former Trabzon municipal solid waste dumpsite were investigated by combining in situ gamma-ray spectrometric measurements with 2D resistivity imaging methods. In the first step, the natural radioelement concentrations on the surface of dumpsite were measured using a portable gamma-ray spectrometer. The average activity concentrations of 238U, 232Th and 40K in the dumpsite are 42.68, 49.88 and 417 Bq/kg, respectively. In addition, radiation hazard parameters were calculated and compared with the international standard values. As a result of the evaluation of the radiological data, it was found that there are no significant radiologic hazards for humans and the environment. In the subsequent stage, 2D electrical resistivity method, using Wenner array, was carried out in this area. The survey was conducted using a multi-electrode resistivity instrument and the measured resistivity profiles were interpreted using RES2DINV program. Electrical resistivity values were obtained from three parallel lines. Results of the resistivity survey show that the waste masses in the study area reach to depths of about 18 m, with very low resistivity values less than 20 Ωm. According to the 2D inverted resistivity sections, low resistivities (<7 Ωm) at the depth corresponds to areas that may be occupied by leachate or sea water. The high resistivity values (>160 Ωm) in profiles B and C are associated with non-degradable waste materials, medical wastes and buried construction materials. Also, very high resistivity zone (874 and 2636 Ωm) in profile A are interpreted as landfill gases.

A study of the spatial distribution of seismicity parameters is undertaken along Turkey and its vicinity, using the Gumbel’s third asymptotic distribution of extreme values (GIII). The data set used spans of 111 years (1900–2010). The seismicity of the whole region is subdivided into equal area mesh of 1° lat. × 1° long. Various seismicity parameters examined, resulted from the application of the GIII method. The results show a quite good correlation between the seismicity parameters and the tectonic regime of the studied area. For instance high values concentrated around North Anatolian Fault. The x 2-test is applied throughout the whole process and in every stage of GIII, in order to check the accuracy of the obtained results. The spatial distribution of upper-bound (ω) formed a W-shape pattern, which shows the difference in the mechanical structure of the materials in the examined area.

In this case study, crustal structure of the Eastern Black Sea (EBS) have been investigated by calculating and inverting group-velocity dispersion data of fundamental mode surface waves (Love and Rayleigh) using single-station method between the periods 4-40 seconds. For this purpose, we have used broad band (BB) recordings of three earthquakes recently occurred easternmost EBS recorded on KOERI (Kandilli Observatory and Earthquake Research Institute) BB stations (BZK, DIKM, KVT, SNOP). Computer Programs in Seismology package version 3.30 (Hermann, 2002) were used to both calculate observed fundamental mode group velocity dispersion curves and inversion of these curves to determine 1D shear wave crustal structure of the region. We have statistically averaged the group velocity dispersion curves for Love and Rayleigh waves. Then, mean dispersion curve of these waves has been inverted to determine 1D shear wave structure represents the region. Consequently, we have determined that there is a low-velocity zone in the upper crust corresponds to Maikop formation. The lower crust consists of oceanic/semi oceanic thickened crust. Moho depth is 31 km.