Investigation of the deep structure of the Sivas Basin (innereast Anatolia, Turkey) with geophysical methods

Sivas Basin is the easternmost and third largest basin of the Central Anatolian Basins. In this study, gravity, aeromagnetic and seismic data are used to investigate the deep structure of the Sivas Basin, together with the well seismic velocity data, geological observations from the surface and the borehole data of the Celalli-1 well. Basement depth is modeled three-dimensionally (3D) using the gravity anomalies, and 2D gravity and magnetic models were constructed along with a N–S trending profile. Densities of the rock samples were obtained from the distinct parts of the basin surface and in-situ susceptibilities were also measured and evaluated in comparison with the other geophysical and geological data. Additionally, seismic sections, in spite of their low resolution, were used to define the velocity variation in the basin in order to compare depth values and geological cross-section obtained from the modeling studies. Deepest parts of the basin (12–13 km), determined from the 3D model, are located below the settlement of Hafik and to the south of Zara towns. Geometry, extension and wideness of the basin, together with the thickness and lithologies of the sedimentary units are reasonably appropriate for further hydrocarbon exploration in the Sivas Basin that is still an unexplored area with the limited number of seismic lines and only one borehole.     

The effects of season on fatty acid composition and ω3/ω6 ratios of northern pike(Esox lucius L.,1758) muscle lipids

In the present study,the effects of season on fatty acid composition,total lipids,and ω3/ω6ratios of northern pike muscle lipids in Kizilirmak River(Kirikkale,Turkey) were investigated.A total of 35 different fatty acids were determined in gas chromatography.Among these,palmitic,oleic,and palmitoleic acids had the highest proportion.The main polyunsaturated fatty acids(PUFAs) were found to be docosahexaenoic acid,eicosapentaenoic acid,and arachidonic acid.There were more PUFAs than monounsaturated fatty acids(MUFA) in all seasons.Similarly,the percentages of ω3 fatty acids were higher than those of total ω6 fatty acids in the fatty acid composition.ω3/ω6 ratios were calculated as 1.53,1.32,1.97,and 1.71 in spring,summer,autumn and winter,respectively.Overall,we found that the fatty acid composition and ω3/ω6 fatty acid ratio in the muscle of northern pike were significantly influenced by season.     

Istanbul Earthquake Rapid Response and the Early Warning System

One hundred strong motion accelerometers have been placed in populated areas of Istanbul, within an area of approximately 50×30 km, to constitute a network that will enable rapid shake map and damage assessment after a damaging earthquake. After triggered by an earthquake, each station will process the streaming strong motion to yield the spectral accelerations at specific periods and will send these parameters in the form of SMS messages to the main data center through available GSM network services. A shake map and damage distribution will be automatically generated. The shake and damage maps will be available on the Internet and will also be pushed to several end users. For earthquake early warning information ten strong motion stations were located as close as possible to the Marmara Fault. The continuous on-line data from these stations will be used to provide near-real time warning for emerging potentially disastrous earthquakes. This revised version was published online in July 2006 with corrections to the Cover Date.     

Modelling scour and deposition in harbours due to complex tsunami-induced currents

In this paper, a set of models responsible for hydrodynamics, sediment transport, and morphological evolution are introduced with their theoretical backgrounds, and it is explained how they are fully connected through a two-way coupling to yield an integrated sediment transport model applicable to tsunami cases. In particular, a fully nonlinear Boussinesq model with bottom shear-induced rotational terms is chosen for the hydrodynamic model in order to provide a better physical approximation of tsunami-related, near-bed hydrodynamics in the nearshore. A finite-volume scheme, stable and suitable for phase-resolving model runs longer than 10 simulated hours, is adopted in the numerical discretization. The accuracy and applicability of the developed model are investigated through numerical tests on various sediment problems in the shallow region. Calculated results agree well with existing experimental records. Finally, an ocean-wide, field-scale simulation of the 2011 Tohoku-oki tsunami is attempted, with a focus on the localized effects of tsunami-induced morphological changes at Crescent City Harbor and Santa Cruz Harbor (USA). Consistent with the reported observations, strong and vortical velocity fields are generated through the model and result in significant changes in morphological configurations. Depth variations and areas of scouring and deposition are compared between modelled and observed records, and the results are discussed. © 2019 John Wiley & Sons, Ltd.     

Landslide susceptibility mapping by frequency ratio and logistic regression methods: an example from Niksar–Resadiye (Tokat,Turkey)

Turkey confronts loss of life and large economic losses due to natural disasters caused by its morphologic structure, geographical placement, and climate characteristics. The Kuzulu (Koyulhisar) landslide, which caused loss of life and property on 17th March 2005, occurred in an area near the country’s most important active fault, the North Anatolian Fault Zone. To mitigate and prevent landslide damages, prediction of landslide susceptibility areas based on probabilistic methods has a great importance. The purpose of this study was to produce a landslide susceptibility map by the logistic regression and frequency ratio methodologies for a 733-km² area near the North Anatolian Fault Zone from the southeast of Niksar to Resadiye in Tokat province. Conditioning parameters, such as elevation, slope gradient, slope aspect, distance to streams, roads, and faults, drainage density, and fault density, were used in the analysis. Before susceptibility analysis, the landslides observed in the area were separated into two groups for use in analysis and verification, respectively. The susceptibility maps produced had five different susceptibility classes such as very low, low, moderate, high, and very high. To test the performance of the susceptibility maps, area under curve (AUC) approach was used. For the logistic regression method, the AUC value was 0.708; while for the frequency rate method, this value was 0.744. According to these AUC values, it could be concluded that the two landslide susceptibility maps obtained were successful.     

Analytical investigation of the observed damage in an RC building after March 08, 2010 Kovancilar-Turkey earthquake

Although the M _w  = 6.1 Kovancilar-Turkey earthquake of March 8, 2010 had a moderate intensity with a recorded PGA of 0.07g, it caused heavy damages in 2870 residential buildings having traditional or masonry structural systems and 42 human loss. Damage has been reported to be particularly concentrated at Kovancilar and Palu counties of Elazig province. Five hours after this earthquake, an aftershock of M _L  = 5.6 with a PGA of 0.08g struck the same region, developing the existing damages in the structures. In order to investigate this significant amount of reported damages under the effect of such low ground shakings, our reconnaissance team arrived at the region and unexpectedly came across a two-story RC building settled on a slope in Yukari Demirci village, which suffered moderate damage during the shakes. The outline of this paper can be summarized as the presentation of the results of the investigations in the order of describing the overall observed damages within the region; evaluation of the recorded motions; the details of the field-work carried out for the two story RC building and the analytical estimation of the site-assessed damages by means of nonlinear dynamic analysis. Employing the gathered data, the building is analytically modeled as plane frames and analyses are performed under the effects of the processed earthquake records, which are applied to the structure one after another in the consistent directions due to the building location. It is shown herein that the structural elements remain in the elastic range subjected to the processed recorded motions; henceforth acceleration time histories are scaled step by step up to 0.40g and computations are repeated for each acceleration level. Comparison with the observed and the analytically obtained damages confirmed that approximately 0.30g of peak ground acceleration should have to be exposed during the earthquakes.     

Application of frequency ratio,statistical index,and weights-of-evidence models and their comparison in landslide susceptibility mapping in Central Nepal Himalaya

The Mugling–Narayanghat road section falls within the Lesser Himalaya and Siwalik zones of Central Nepal Himalaya and is highly deformed by the presence of numerous faults and folds. Over the years, this road section and its surrounding area have experienced repeated landslide activities. For that reason, landslide susceptibility zonation is essential for roadside slope disaster management and for planning further development activities. The main goal of this study was to investigate the application of the frequency ratio (FR), statistical index (SI), and weights-of-evidence (WoE) approaches for landslide susceptibility mapping of this road section and its surrounding area. For this purpose, the input layers of the landslide conditioning factors were prepared in the first stage. A landslide inventory map was prepared using earlier reports, aerial photographs interpretation, and multiple field surveys. A total of 438 landslide locations were detected. Out these, 295 (67 %) landslides were randomly selected as training data for the modeling using FR, SI, and WoE models and the remaining 143 (33 %) were used for the validation purposes. The landslide conditioning factors considered for the study area are slope gradient, slope aspect, plan curvature, altitude, stream power index, topographic wetness index, lithology, land use, distance from faults, distance from rivers, and distance from highway. The results were validated using area under the curve (AUC) analysis. From the analysis, it is seen that the FR model with a success rate of 76.8 % and predictive accuracy of 75.4 % performs better than WoE (success rate, 75.6 %; predictive accuracy, 74.9 %) and SI (success rate, 75.5 %; predictive accuracy, 74.6 %) models. Overall, all the models showed almost similar results. The resultant susceptibility maps can be useful for general land use planning.