Quantifying geological structures of the Nigde province in central Anatolia,Turkey using SRTM DEM data

A digital terrain model and a 3D fly-through model of the Nigde province in central Anatolia, Turkey were generated and quantitatively analyzed employing the shuttle radar topographic mission (SRTM) digital elevation model (DEM). Besides, stream drainage patterns, lineaments and structural–geological features were extracted and analyzed. In the process of analyzing and interpreting the DEM for landforms, criteria such as color and color tones (attributes of heights), topography (shaded DEM and 3D fly-through model) and stream drainage patterns were employed to acquire geo-information about the land, such as hydrologic, geomorphologic, topographic and tectonic structures. In this study, the SRTM DEM data of the study region were experimentally used for both DEM classification and quantitative analysis of the digital terrain model. The results of the DEM classification are: (1) low plain including the plains of Bor and Altunhisar (20.7%); (2) high plain including the Misli (Konakli) plain (28.8%); (3) plateau plain including the Melendiz (Ciftlik) plateau plain (1.0%); (4) mountain including the Nigde massif (33.3%); and (5) high mountain (16.2%). High mountain areas include a caldera complex of Mt Melendiz, Mt Hasan and Mt Pozanti apart from the Ala mountains called Aladaglar and the Bolkar mountains called Bolkarlar in the study region (7,312 km²). Analysis of both the stream drainage patterns and the lineaments revealed that the Nigde province has a valley zone called Karasu valley zone (KVZ) or Nigde valley zone (NVZ), where settlements and agricultural plains, particularly the Bor plain in addition to settlements of the Bor town and the central city of Nigde have the most flooding risk when a heavy raining occurs. The study revealed that the NVZ diagonally divides the study region roughly into two equal parts, heading from northeast to southwest. According to the map created in this study, the right side of the NVZ has more mountainous area, where the Aladaglar is a wildlife national park consisting of many species of fauna and flora whereas the left side of the NVZ has more agricultural plain, with exception of a caldera complex of Mt Melendiz and volcanic Mt Hasan. The south of the study region includes the Bolkarlar. In addition, the Ecemis fault zone (EFZ) lying along the Ecemis rivulet, running from north to south at the west side of the Aladaglar, forms the most important and sensitive location in the region in terms of the tectonics.     

Multi-risk governance for natural hazards in Naples and Guadeloupe

Technical and institutional capacities are strongly related and must be jointly developed to guarantee effective natural risk governance. Indeed, the available technical solutions and decision support tools influence the development of institutional frameworks and disaster policies. This paper analyses technical and institutional capacities, by providing a comparative evaluation of governance systems in Italy and France. The focus is on two case studies: Naples and Guadeloupe. Both areas are exposed to multiple hazards, including earthquakes, volcanic eruptions, landslides, floods, tsunamis, fires, cyclones, and marine inundations Cascade and conjoint effects such as seismic swarms triggered by volcanic activity have also been taken into account. The research design is based on a documentary analysis of laws and policy documents informed by semi-structured interviews and focus groups with stakeholders at the local level. This leads to the identification of three sets of governance characteristics that cover the key issues of: (1) stakeholders and governance level; (2) decision support tools and mitigation measures; and (3) stakeholder cooperation and communication. The results provide an overview of the similarities and differences as well as the strengths and weaknesses of the governance systems across risks. Both case studies have developed adequate decision support tools for most of the hazards of concern. Warning systems, and the assessment of hazards and exposure are the main strengths. While technical/scientific capacities are very well developed, the main weaknesses involve the interagency communication and cooperation, and the use and dissemination of scientific knowledge when developing policies and practices. The consequences for multi-risk governance are outlined in the discussion.     

Active faulting and natural hazards in Armenia, eastern Turkey and northwestern Iran

Active fault zones of Armenia, SE Turkey and NW Iran present a diverse set of interrelated natural hazards. Three regional case studies in this cross-border zone are examined to show how earthquakes interact with other hazards to increase the risk of natural disaster. In northern Armenia, a combination of several natural and man-made phenomena (earthquakes, landslides and unstable dams with toxic wastes) along the Pambak-Sevan-Sunik fault (PSSF) zone lowers from 0.4 to 0.2–0.3g the maximum permissible level (MPL) of seismic hazard that may induce disastrous destruction and loss of life in the adjacent Vanadzor depression.

In the Ararat depression, a large active fault-bounded pull-apart basin at the junction of borders of Armenia, Turkey, Iran and Azerbaijan, an earthquake in 1840 was accompanied by an eruption of Ararat Volcano, lahars, landslides, floods, soil subsidence and liquefaction. The case study demonstrates that natural hazards that are secondary with respect to earthquakes may considerably increase the damage and the casualties and increase the risk associated with the seismic impact.

The North Tabriz–Gailatu fault system poses a high seismic hazard to the border areas of NW Iran, eastern Turkey, Nakhichevan (Azerbaijan) and southern Armenia. Right-lateral strike–slip motions along the North Tabriz fault have given rise to strong earthquakes, which threaten the city of Tabriz with its population of 1.2 million.

The examples illustrate how the concentration of natural hazards in active fault zones increases the risk associated with strong earthquakes in Armenia, eastern Turkey and NW Iran. This generally occurs across the junctions of international borders. Hence, the transboundary character of active faults requires transboundary cooperation in the study and mitigation of the natural risk.     

Structural interpretation of the Marmara region, NW Turkey, from aeromagnetic, seismic and gravity data

The seismically active Marmara region, located in NW Turkey, lies on the westward end of the North Anatolian Fault (NAF). The NAF is well defined on land. Previous investigations of its extension in the Marmara Sea include marine bathymetry, seismological activity and seismic profiles. In this study, faults and their configurations identified inland are extended into the Marmara Sea by means of aeromagnetic anomalies, as well as seismic and gravity profiles. The deep structure was resolved by constructing a map of the Tertiary bottom. Shallow Curie isotherm was determined by spectral analysis, indicating a thinner crust in the northern Marmara depression area with respect to the continental crust. A combination of the geophysical data allows us to propose the existence of subsidence and isostatic equilibrium in the northern Marmara Sea. A less-active zone identified in the central high zone dividing the Marmara Sea into two parts may also be deduced from the seismic data. This structural arrangement may play a key role in earthquakes that will affect the surrounding regions.     

Hydrochemistry and salt-water intrusion in the Van aquifer,east Turkey

Groundwater in the Van coastal aquifer is one of the main sources of potable, industrial and irrigational water in Van City, because of its semi-arid climate. Groundwater extraction has been in excess of replenishment owing to increased agricultural and economic activities and a growing population during the last 20 years. A hydrochemical survey of the Van aquifer provided data on the groundwater chemistry patterns and the main mineralization processes. The main processes influencing the groundwater chemistry are salinisation from salt-water intrusion, silicate mineral dissolution, cation exchange and human activity. Deterioration in water quality has resulted from intrusion of the salt water of Lake Van along the coastal regions into the Van plain. At present, the mixing rate of salt water in the Van aquifer is between 1 and 5.5% and salt water has already invaded about 5 km inland in the iskele and the airport region.     

高亚洲冰川区SRTM C-波段DEM数据透射深度研究

SRTM数据是研究冰量变化的重要数据之一。基于SRTM C-波段和X-波段的高程数据,对高亚洲不同冰川区SRTM C-波段数据的透射深度进行了研究。结果表明：高亚洲地区SRTM_C透射深度的空间分布特征存在较大差异,其中藏色岗日地区的透射深度最大为（5.3±2.1） m,中天山和念青唐古拉西段地区的透射深度最小仅为（0.8±0.6） m。透射深度整体空间分布呈由高亚洲边缘地区向青藏高原内陆先减小后增大,到羌塘高原地区SRTM_C的透射深度最大的趋势。气温和降水量的空间差异共同作用是导致SRTM_C透射深度呈上述分布状况的主要因素。此外,SRTM X-波段数据的覆盖状况和冰川样本数量的选择会导致不同研究估算出的SRTM_C透射深度存在不确定性。     

Determination of natural radioactivity levels in soil and travertine of the region of Tokat and Sivas,Turkey

In this study, the environmental radioactivity measurements for Tokat and Sivas provinces in the northeast of Turkey were performed. Using gamma ray spectrometry, the activity concentrations of natural radionuclides in soil and travertine samples (²³²Th, ²²⁶Ra, and ⁴⁰K) were determined. The annual effective dose equivalent, the absorbed doses rate in air, the radium equivalent, and the external hazard index were obtained from these activities. The activity concentrations vary from 9.09 to 17.04 Bq kg^?1 for ²³²Th, from 36.53 to 76.95 Bq kg^?1 for ²²⁶Ra, and from 216.56 to 576.59 Bq kg^?1 for ⁴⁰K in soil samples. The activity concentrations in travertines vary from 15.99 to 21.01 Bq kg^?1 for ²³²Th, from 19.89 to 67.71 Bq kg^?1 for ²²⁶Ra, and from 179.89 to 314.43 Bq kg^?1 for ⁴⁰K. The average dose rate in air for soil and travertine samples was 43.41 and 41.05 nGy h^?1 respectively. The obtained results are presented and compared with other studies, and the results of this study are lower than the international recommended value (55 nGy h^?1) given by UNSCEAR ( 2000). The results show that the region has a background radiation level within the natural limits.     

Seismic hazard analysis of Sinop province,Turkey using probabilistic and statistical methods

Using 4.0 and greater magnitude earthquakes which occurred between 1 January 1900 and 31 Dec 2008 in the Sinop province of Turkey this study presents a seismic hazard analysis based on the probabilistic and statistical methods. According to the earthquake zonation map, Sinop is divided into first, second, third and fourth-degree earthquake regions. Our study area covered the coordinates between 40.66°– 42.82°N and 32.20°– 36.55°E. The different magnitudes of the earthquakes during the last 108 years recorded on varied scales were converted to a common scale (Mw). The earthquake catalog was then recompiled to evaluate the potential seismic sources in the aforesaid province. Using the attenuation relationships given by Boore et al. (1997) and Kalkan and Gülkan (2004), the largest ground accelerations corresponding to a recurrence period of 475 years are found to be 0.14 g for bedrock at the central district. Comparing the seismic hazard curves, we show the spatial variations of seismic hazard potential in this province, enumerating the recurrence period in the order of 475 years.     

应用遥感技术研究吉林省的地质灾害

利用遥感技术对吉林省地质灾害进行了较详细的解译，共解译出128处滑坡，其中软岩滑坡66处，碎石滑坡50处，硬岩滑坡12处，解译出规模较大的泥石流126处，崩塌4处，沼泽化严重的地带百余处，对土地沙化，土地盐碱化，水土流失，水库淤积及河流改道等也做了较详细的解译，提出了各种地质灾害的形成条件及影响因素，滑坡，泥石流、崩塌的形成与地形坡度，岩土体类型，水网密度等关系密切，地震也可诱导滑坡产生，水土流失，水库淤积主要与地形坡度、植被覆盖率，岩土体类型及水网密度有关，河流改道是第四纪地壳运动的区域性断块隆起和凹陷，或断裂的相对升降运动，或地壳上升运动的差异性所致，土地沼泽化、土化盐碱化主要形成于排水不畅地带，对不同类型的地质灾害提出了相应的防治对策。     

基于SRTM DEM的地形起伏度对天水市黄土滑坡的影响分析

以天水市辖区30 m分辨率的SRTM DEM数据为基础,首先利用GIS空间分析模块中邻域统计分析法,依次选取2×2、3×3、4×4、…、28×28、29×29、30×30共29个矩形邻域分析窗口,运用均值变点分析法进行最佳计算单元的计算分析。结果表明：12×12的网格大小（12.96×10⁴ m²）为曲线突变的拐点,作为曲线由陡变缓的阈值,确定12×12的网格大小（12.96×10⁴ m²）为研究区地形起伏度计算的最佳单元,生成研究区地形起伏度分级图。进而采用确定性系数法（CF）、证据权法、信息量法和条件概率法对研究区发育的黄土滑坡灾害与地形起伏度之间的相关关系进行了定量分析。研究结果表明,区内地形起伏度影响因子层中地形起伏度60~120 m的分级因子层为黄土滑坡灾害的易发因子层,而其中60~90 m区间的值最大,为黄土滑坡灾害的优势因子区间,对滑坡的响应最敏感。     

Quality, palynology, and palaeoenvironmental interpretation of the Ilgin lignite, Turkey

The Ilgin lignite field can be subdivided into the Haramiköy and Kurugöl areas which are separated by an area of basement and a fault. The lignite-bearing sequence consists mainly of fluvial and lacustrine Neogene deposits. The Ilgin lignite, averaging 8 m (up to 25 m) thick, is blackish brown and dark brown in colour. The lignite contains abundant brown wood, plant remains and white gastropod shells. Samples have an average of 38.9% moisture on an as-received basis and a mean of 3.9% total sulphur on an air-dried basis. Geochemical analysis, using an ICP-MS, was undertaken. Thirteen lignite core samples from three boreholes drilled in the Kurugöl area were ashed at 750°C. The average trace element contents of the lignite show a higher concentration of U (average 43 ppm) when compared to the range for most coals in the world, while the others (Ti, P, Sc, Be, Mn, Co, Cu, Zn, Ga, As, Rb, Sr, Zr, Nb, Mo, Cs, Ba, Y, Ta, W, Tl, Pb, Bi, Th, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu) agree with the global ranges. The Ilgin lignite is identified as of Middle Miocene (Middle Serravallian) age and occurs within lacustrine sediments deposited under subtropical climatic conditions.     

Weathering of fuel oil spill on the east Mediterranean coast, Ashdod, Israel

Residual fuel oil spilled into the sea from the Eshkol power station on 8 February, 1998 contaminated about 9 km of the foreshore north of the Ashdod harbour. A study of the aliphatic, polycyclic alkane and polyaromatic hydrocarbon (PAH) composition of the spilled oil shows rapid weathering in the early stages followed by gradual slowdown after about three months. Weathering of isoprenoids and PAH compounds and variation in Pr/Ph ratio appear to occur almost contemporaneously with that of n-alkanes, at a relatively moderate level of degradation, when much of the >C₂₀ n-alkane envelope is still well preserved. Depletion of various compounds in accordance with molecular size rather than molecular structure appears to imply that physical weathering processes, i.e. evaporation and perhaps flushing due to wave energy, might have played an important role in the degradation of the spilled residual fuel oil in this study case.     

津巴布韦东部Mutema地区地球化学特征及成矿预测

根据津巴布韦东部地区1∶25万区域地球化学调查成果,运用地质、化探、遥感等对该地区进行了地球化学特征、成矿规律研究和找矿预测,确立了以金为主的Tarka地区和以Ni,Cu为主的Limeworks,Mutema地区为找矿靶区;认为Tarka地区金矿并非粗玄岩次生富集而成,而是受构造控制并与热液活动引起的金活化富集有关;中部的高镍异常区是寻找红土型镍矿的有利部位。     

Visualization of uncertainty in natural hazards assessments using an interactive cartographic information system

Natural hazard assessments are always subject to uncertainties due to missing knowledge about the complexity of hazardous processes as well as their natural variability. Decision-makers in the field of natural hazard management need to understand the concept, components, sources, and implications of existing uncertainties in order to reach informed and transparent decisions. Until now, however, only few hazard maps include uncertainty visualizations which would be much needed for an enhanced communication among experts and decision-makers in order to make informed decisions possible. In this paper, an analysis of how uncertainty is currently treated and communicated by Swiss natural hazards experts is presented. The conducted expert survey confirmed that the communication of uncertainty has to be enhanced, possibly with the help of uncertainty visualizations. However, in order to visualize the spatial characteristics of uncertainty, existing uncertainties need to be quantified. This challenge is addressed by the exemplary simulation of a snow avalanche event using a deterministic model and quantified uncertainties with a sensitivity analysis. Suitable visualization methods for the resulting spatial variability of the uncertainties are suggested, and the advantages and disadvantages of their implementation in an interactive cartographic information system are discussed.     

Mud volcanoes, olistostromes and Argille scagliose in the Mediterranean region

Tectonic and sedimentary mélanges, rocks with block-in-matrix fabric often referred to as 'chaotic', are widespread in the circum-Mediterranean collisional orogenic belts as well as in submerged Mediterranean Arcs. These rock types have been defined originally as 'Argille scagliose' (Bianconi, 1840) and 'olistostromes' (Flores, 1955, 1959) in the outcrops of the Apennine chain (Italy). Both terminology and concepts have undergone a rather complex evolution through time owing to the gradual recognition of similar chaotic bodies in all the circum-Mediterranean orogenic belts. Submarine mud volcanoes of the Mediterranean region, also composed by block-in-matrix, more commonly referred to as mud breccias, have a much younger history. These mud breccias were discovered in 1981 and, since then, a growing number of sea-going geophysical and geological expeditions have allowed the recognition of a major mud volcano belt in the Eastern Mediterranean and of a number of mud diapirs and mud volcano fields from the Black Sea to the Gulf of Cadiz. Structural, textural and genetic similarities between the mud breccias of the Mediterranean mud volcanoes and the olistostromes and Argille scagliose of the Apennines were noted from the very beginning, but the matter has not been the focus of any detailed study. In this paper, the use of the terms in the geological literature is analysed, the distribution of these rock units in the Mediterranean region explored and the assumed genetic processes are identified in order to formulate a common genetic model that can be applied to the evolution of the circum-Mediterranean sedimentary basins.     

Assessment of predominant frequencies using ambient vibration in the Kachchh region of western India: implications for earthquake hazards

The Kachchh region is the second most seismically active region in India after the Himalaya. One of the disastrous Indian earthquakes of the millennium was the Bhuj earthquake of January 26, 2001, which caused about 14,000 casualties and huge property damage. The main reason for such devastation is due to lack of earthquake awareness and poor construction practices. Hence, an increase in the knowledge and awareness, based on improved seismic hazard assessment, is required to mitigate damage due to an earthquake. Natural predominant ground frequencies have been investigated in the Kachchh region of western India using ambient vibrations. The horizontal-to-vertical spectral ratio technique has been applied to estimate the predominant frequency at 126 sites. The ambient vibration measurements were conducted for about 1 h at each site in the continuous mode recording at 100 samples/s. We have validated the estimated predominant frequency with earthquake data recorded at six broadband stations in the region. It has been observed that geological time period has a significant effect on predominant frequency of the ground. The estimated predominant frequencies vary from 0.24 to 2.25 Hz for the Quaternary, 0.41–2.34 Hz for the Tertiary, 0.32–4.91 Hz for the Cretaceous, and 0.39–8.0 Hz for the Jurassic/Mesozoic. In the Deccan trap, it varies from 1.30 to 3.80 Hz. We found distinct variation of predominant frequencies of sites associated with hard rock and soft soil. The predominant frequencies were related to the thickness of the sediments, which are deduced by other geophysical and geological methods in the region. Our results suggest that frequencies of the region reveals the site characteristics that can be considered for studying the seismic risks to evolve a plan for disaster risk mitigation for the region.     

Genetic characterization of gas shows in the east Mediterranean offshore of southwestern Israel

Drilling in the eastern continental margin of the Levant Basin (southeastern Mediterranean), offshore southwestern Israel encountered light oil shows, numerous vertically stacked gas pockets and, more recently, commercial gas discoveries. Chemical and stable isotopic compositions obtained for 24 gas samples from Middle Jurassic to Pliocene reservoir rocks suggest that they represent a few genetic systems which are distributed vertically in the section in accordance with the stratigraphy. These groups include bacterial gas in the Pliocene, a mixture of bacterial and thermogenic gas in the Lower Cretaceous, and thermogenic gas in the Jurassic section. The bacterial gases in the Pliocene and the Lower Cretaceous appear not to be cogenetic, and likewise the thermogenic gas in the Lower Cretaceous and the Jurassic sections. Excluding one case, where the thermogenic gas appears to represent phase separation from a probably cogenetic light oil, the relationship of either the bacterial or other thermogenic gas samples to particular potential source rocks in the section or to light oil shows encountered in the Middle Jurassic section is at this stage inconclusive.