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The main purpose of this study was to compare the performance and validation of six machine learning models (extreme gradient boosting, random forest, artificial neural network, support vector machine, C4.5 decision tree, and naive Bayes) in landslide susceptibility modelling. The province of Rize, which has the highest rate of landslide events in Türkiye, was chosen as the study area. The conditioning factors (distance to roads, lithology, drainage density, slope, topographic wetness index (TWI), soil depth, distance to rivers, land use, NDVI, plan curvature, elevation, aspect, profile curvature) affecting the landslide were determined using the ReliefF method. A total of 516 landslides were identified for creating models, comparing performance, and validating results. The performance and validation of the models were determined by the receiver operating characteristics (ROC), sensitivity, specificity, accuracy, and kappa index. The results show that the XGBoost model outperforms the other five machine learning models in terms of accuracy and performance and is the most effective model for generating landslide susceptibility maps in Rize (Türkiye). [ABSTRACT FROM AUTHOR]

The aim of this study is to determine the engineering properties of the sediments and the submarine mass movements that are formed in the one of the most important tectonic lake of Turkey, Hazar Lake, located in the East Anatolian Fault Zone. For this purpose, laboratory experiments were carried out on undisturbed soil samples taken from the points that were determined by using high-resolution seismic data of the lake. According to the results of the experiments, the soils at the areas where streams discharge into Hazar Lake are Non-Plastic Course Silt (MLN), and around the mid-parts of the lake is High Plastic Silt (MH). Dry unit weight values of soils increase with depth, while porosity and void ratio values decrease. The strength value of MLN is much higher than MH type soils. The strength of MH type soil is quite low since it is not tightened enough. In the seismic profiles of Hazar Lake, the soil thickness is about maximum 3 m on steep slopes, while the soil thickness can reach up to 10 m on slopes having lower dips. On the slopes where the soil thickness is higher, submarine mass movements developed by the own weight of the soil especially. These types of mass movements are slumptype slides in which traces of plastic deformation and circular failure surfaces are clearly visible. Considering that the soil strength on the slopes of Hazar Lake are very low, it can be said that these mass movements were formed by the weight of the sediments and, the earthquakes that took place in the Eastern Anatolian Fault Zone (DAFZ) also catalyze these mass movements to occur. [ABSTRACT FROM AUTHOR]

Turkey is highly prone to landslides because of the geological and geographic location. The study area, which is located in a tectonically active region, has been significantly affected by mass movements. Flow type landslides are frequently observed due to this location. This study aims at determining the source area and propagation of debris flows in the study area. We used the heuristic method to extract source areas of debris flow, and then used receiver operating characteristic (ROC) curve analysis to assess the performance of the method, and finally calculated the Area under curve (AUC) values being 83.64% and 80.39% for the success rate and prediction rate, respectively. We calculated potential propagation area and runout distance with Flow-R software. In conclusion, the obtained results (susceptibility map, propagation and runout distance) are very important for decision-makers at the region located on an active fault zone, which is highly prone to natural disasters. The outputs of this study could be used in site selection studies, designing erosion prevention systems and protecting existing human-made structures. [ABSTRACT FROM AUTHOR]

This study was carried out for determining the type, and factors of mass movements occurred in Upper Eocene-Lower Miocene mudstone and sandstone alternation (with varying ratios) of the Elmalı Formation. Those sediments crop out in a vast area in SW Turkey. The main mass movement type is determined as an earthflow understanding of tilting trees, electric pole and bumpy topography. Locally, complex mass wasting including rotational landslide with various sizes, creep, earthflow and translational movement were also determined during the field study. They are threatening people's life and property. Slope inclination, bed attitudes, joint measurement, hydrogeological observations, in situ strength measurements, geophysical application and rock sampling were performed during the field analysis. In addition, petrographic investigations, XRF and XRD analyses were performed for determining the contents of sample. Basic physico-mechanical properties, including specific gravity, porosity, Atterberg limits of samples were determined in the laboratory. Tectonic history was responsible from sheared, overturned, faulted and fractured lithology. The chaotic mudstone behaves like soil mass on hard-durable sandstone beds. Mid to high inclined slope promote the earthflow. In addition, the surface and ground water increase unstable mass weight and act as a lubricant on durable sandstone, which promote earthflow. The toe of the slope eroded and removed by streams. Thus, the earthflow continues on slope. In addition, local disturbance due to human impact (road cut, settlements, garden opening) caused small-scale but more dangerous complex mass movement. [ABSTRACT FROM AUTHOR]

This study focuses on revealing the landslide susceptibility of mainly the Kelemen Valley and adjacent valleys in the Western Black Sea Region of Turkey by investigating the parameters causing landslide occurrences in the region in a GIS environment and applying the frequency rate method on landslide-prone areas. Many buildings and houses in the study area, 382 houses to be exact, had to be evacuated by the General Directorate of Disaster Affairs of Turkey based on the findings from landslide studies conducted in the region since 1950 and were declared 'unsuitable for construction and residence due to disaster.' Therefore, it is of a vital significance to disclose the factors of landslide occurrences in the Kelemen Valley and consequently to prepare landslide susceptibility maps. For this purpose, 82 landslide exposed areas are determined by field surveys and checked against satellite imagery. All 82 landslides are found to have occurred in the Cretaceous Ulus Formation with the same climate and same vegetation, which are not considered distinctive parameters for the region. These findings have given rise to exclude these parameters from analyses on the basis that they are proclaimed as common parameters; instead, the parameters such as slope, aspect and distance to river are taken into consideration and assessed in ArcGIS™ software. Finally, the landslide susceptibility of the region has been obtained. Furthermore, a comparison is conducted between the existing landslides and the outcome map, and it is deduced that the map produced has a correlation ratio of 86 % with the existing occurrences for high-risk areas. This finding clearly dictates that landslide-prone areas need to be accounted for when planning for new settlement areas. [ABSTRACT FROM AUTHOR]

Abstract: An overview is given of mass wasting features along the slopes of the Sea of Marmara, Turkey, based on new data and previously published information. The Sea of Marmara is characterized by active tectonics along the North Anatolian Fault and by eustatic sea level changes controlling the connections both to the Mediterranean and Black Sea (i.e. lacustrine and marine conditions during sea-level low and high stands, respectively). High resolution bathymetric data, subsurface echo-sounder and seismic reflection profiling, seafloor visual observations, as well as stratigraphic analysis of sediment cores have been used to identify, map and date submarine slope failures and mass wasting deposits. Gravity mass movements are widespread on the steep slopes of the Sea of Marmara, and range from small scale slope failures, mainly located within the canyons, to wider unstable areas (20 to 80km2). The largest mass wasting features, i.e. the Tuzla, Ganos and Yalova complexes, have been analyzed in connection with crustal deformation. These gravitational gliding masses are probably induced by the transtensional deformation within the crust. Moreover, age determination of landslides and debris flows indicate that they were more frequent during the last transgressive phase, when the rate of terrigenous sediments supplied by the canyons to the deep basin was higher. We discuss these results taking into account activity, pre-conditioning and trigger mechanisms for slope instability with respect to tectonics and paleo-environmental changes induced by sea-level oscillations. [Copyright &y& Elsevier]

The main purpose of this study is to develop a new hazard evaluation technique considering the current limitations, particularly for shallow landslides. For this purpose, the Buyukkoy catchment area, located in the East Black Sea Region in the east of Rize province and the south of Cayeli district, was selected as the study area. The investigations were executed in four different stages. These were (1) preparation of a temporal shallow landslide inventory of the study area, (2) assessment of conditioning factors in the catchment, (3) susceptibility analyses and (4) hazard evaluations and mapping. A total of 251 shallow landslides in the period of 1955-2007 were recognised using different data sources. A 'Sampling Circle' approach was proposed to define shallow landslide initiation in the mapping units in susceptibility evaluations. To accomplish the susceptibility analyses, the method of artificial neural networks was implemented. According to the performance analyses conducted using the training and testing datasets, the prediction and generalisation capacities of the models were found to be very high. To transform the susceptibility values into hazard rates, a new approach with a new equation was developed, taking into account the behaviour of the responsible triggering factor over time in the study area. In the proposed equation, the threshold value of the triggering factor and the recurrence interval are the independent variables. This unique property of the suggested equation allows the execution of more flexible and more dynamic hazard assessments. Finally, using the proposed technique, shallow landslide initiation hazard maps of the Buyukkoy catchment area for the return periods of 1, 2, 5, 10, 50 and 100 years were produced. [ABSTRACT FROM AUTHOR]

Recent mass movements in the Kocaeli Province, Turkey in 2010 caused damage to people, property and infrastructure, especially in Izmit and its vicinity. The causes and impact of these mass movements are outlined, so as to increase awareness of their dangerous aspects. Some of these mass movement events took place in urban areas, bringing attention to the need for better and more effective land use practices. The impact of these movements indicates the benefit there would be from geology and engineering geology in the planning of any property development and land use. [ABSTRACT FROM AUTHOR]

Surface rupture and source fault of the 20 February 1956 Eskişehir earthquake have been a matter of debate that potentially contributes towards the understanding of the active deformation and seismic risk in the highly populated NW Anatolia. Field observations on the two fault segments (namely Kavacık and Uludere faults) in the north of the Eskişehir graben revealed evidences of co-seismic surface rupture and mass movements during the Eskişehir earthquake. Surface rupture was observed as a 2.5m wide, a 100m long and ca. 20 cm deep asymmetric depression in the Gümüşlü valley, 2 km east of the Uludere village. A trench dug on this depression confirms a prominent high-angle south dipping fault (dominantly left lateral strike slip) and two faint north-dipping antithetics as clear noticeable shear zones in organic-rich thick soil. Mass failures are particularly observed in spring depressions filled with loose torrent and carbonaceous material in front of the fault scarp. Some rock slides of several tens of meters in size that obviously require significantly high ground shaking were also developed on steep fault scarps. The orientation of the principal stress tensor as deduced from the surface rupture of the Eskişehir earthquake displays clear inconsistency with the geometry of prominent faults in the area. We concluded that this disagreement may be explained by a curved surface rupture. The western and eastern tips of this rupture are EW trending and the probable NW-running part in the middle would correspond to the bounding zone between two right-stepping faults. [ABSTRACT FROM AUTHOR]

Abstract: We investigated Gemlik Bay of the Marmara Sea with an extensive high-resolution shallow seismic survey to locate and map active traces of the southern strand of the North Anatolian Fault (NAF). The southern strand splits from the main trace of the North Anatolian Fault about 80 km southeast of İzmit and extends as a continuous trace to the west for about 140 km to Gemlik Bay where it enters the Sea of Marmara. The seismic profiles reveal many faults that offset the Quaternary deposits. We interpret that four major fault zones play a significant role in shaping Gemlik Bay, the Gemlik, Kocadere–Mudanya, Gençali and Armutlu Faults, and propose that these faults are responsible for the formation of two prominent morphological features in the bay, namely Burgaz Depression and Gemlik Rise which are a pull-apart basin and a push-up structure, respectively. Closely spaced profiles to interpret the fault patterns and complex kinematics, therefore, are shown to be necessary in such areas. Besides active fault traces along the profiles, we also observed mass movements along the southern shore, offshore Mudanya–Zeytinbağı and Kurşunlu in the study area. Although no destructive earthquakes were experienced in the region recently the mass movements observed on the seafloor indicate remarkable past activity along the southern strand of the North Anatolian Fault which is overshadowed by the northern strand in 20th century from seismicity point of view. [Copyright &y& Elsevier]

Structural, mass-wasting and sedimentation processes along an active dextral shear zone beneath the Gulf of Saros and the NE Aegean Sea were investigated on the basis of new high-resolution swath bathymetric data and multi-channel seismics. A long history of dextral shearing operating since the Pliocene culminated in the formation of a NE-SW-trending, ca. 800-m-deep basin (the so-called inner basin) in this region, which is bordered by a broad shelf along its northern and eastern sides and a narrow shelf at the southern side. The western extension of the North Anatolian Fault Zone (the Ganos Fault) cuts the eastern shelf along a narrow deformation zone, and ends sharply at the toe of the slope, where the strain is taken up by two NE-SW-oriented fault zones. These two fault zones cut the basin floor along its central axis and generate a new, Riedel-type pull-apart basin (the so-called inner depression). According to the bathymetric and seismic data, these basin boundary fault zones are very recent features. The northern boundary of the inner depression is a through-going fault comprising several NE-SW- and E-W-oriented, overlapping fault segments. The southern boundary fault zone, on the other hand, consists of spectacular en-echelon fault systems aligned in NE–SW and WNW–ESE directions. These en-echelon faults accommodate both dextral and vertical motions, thereby generating block rotations along their horizontal axis. As the basin margins retreat, the basin widens continuously by mass-wasting of the slopes of the inner basin. The mass-wasting, triggered by active tectonics, occurs by intense landsliding and channel erosion. The eroded material is transported into the deep basin, where it is deposited in a series of deep-sea fans and slumps. The high sedimentation rate is reflected in an over 1,500-m-thick basin fill which has accumulated in Pliocene–Quaternary times. [ABSTRACT FROM AUTHOR]

There exist a number of landslides along the north Anatolian fault zone (NAFZ) between Tasova and Alparslan in Amasya province in Turkey. These landslides extending over an area of 2.5 × 6.0 km are triggered by steepening of slopes due to undercutting by the Yesilirmak River and groundwater fluctuations. The landslides have affected 30 buildings in the western part of Tasova. In this study, in order to investigate the engineering geological characteristics of the landslides and their environmental impacts, representative samples from geological units were collected and a total of six boreholes were drilled. Plastic pipes were installed into the boreholes to measure the groundwater fluctuations and to determine the position of the sliding surface. For a two-year monitoring period, using a GPS linked to a fixed station system, the magnitude of the movements ranged between 11.7 and 17.6 cm at the toe of landslide. The landslides that occurred in the study area were in the form of retrogressive circular and multiple circular failures. The factor of safety along a number of cross-sections calculated by the limit-equilibrium method of analysis is 0.96 in static condition. After further analyses, construction of a toe buttress with surface drainage may be suggested as a remedial measure to minimize the effects of these landslides. [ABSTRACT FROM AUTHOR]

The current study deals with a catastrophic landslide that occurred due to heavy rainfall in Adana, Southern Turkey in 2001. The research area, which is one of the largest populated districts in Adana, and one of the most tropical places between the Middle East and southern Europe, has about 25,000 people. On the basis of geological and geotechnical surveys, the landslide phenomena and the effects of landslide are examined. To understand the slide mechanism of the landslide, ground reconnaissance, laboratory and in situ tests are conducted. It is observed that the clayey and silty layers of the site are heavily saturated due to extreme rainfall in winter, and consequently sheared. The landslide consists of a block sliding in the upper portions and a debris flow/soil flow component around the margins of the sliding blocks in the middle parts and at the toe. Although there was no loss of human life, it has caused significant economic losses. Besides, it is determined that if precautions are not taken around the landslide area, larger landslides could definitely occur in the future. [ABSTRACT FROM AUTHOR]

Abstract: The Ardesen area is prone to landslides because of the climate conditions, geologic, and geomorphologic characteristics of the region. As in previous years, in 2001 due to heavy rainfall there were many landslides resulting in damage and human casualties. There is still a great danger of further landslides in the region. Therefore, it is vitally important to prepare a landslide susceptibility map of the region. In this study, the analytical hierarchy process (AHP), the statistical index (Wi), and weighting factor (Wf) methods were used to produce and later compare three susceptibility maps. For this purpose, thematic layers including landslide inventory, lithology-weathering, slope, aspect, land cover, distance to stream, drainage density, and distance to road were used. In this study area, 98% of landslides occurred in highly or completely weathered units. Lithology-weathering, land cover, and slope data layers were found to be important factors in the study area. To confirm the practicality of the three susceptibility maps were compared with a landslide activity map containing 16 active landslide zones. The outcome was that the active landslide zones do not completely fit into the high and very high susceptibility classes. But 81.3% of these landslide zones fall into the high and very high susceptibility zones of the AHP method while this is 62.5% in the case of Wi method, and 68.8% with the Wf method. In spite of the results obtained in this study, the development of a susceptibility map is usually determined by the needs and available resources. The results showed that the AHP method gave a more realistic picture of the actual distribution of landslide susceptibility, than the Wi and Wf methods. [Copyright &y& Elsevier]

Debris flow is one of the most destructive mass movements. Sometimes regional debris flow susceptibility or hazard assessments can be more difficult than the other mass movements. Determination of debris accumulation zones and debris source areas, which is one of the most crucial stages in debris flow investigations, can be too difficult because of morphological restrictions. The main goal of the present study is to extract debris source areas by logistic regression analyses based on the data from the slopes of the Barla, Besparmak and Kapi Mountains in the SW part of the Taurids Mountain belt of Turkey, where formation of debris material are clearly evident and common. In this study, in order to achieve this goal, extensive field observations to identify the areal extent of debris source areas and debris material, air-photo studies to determine the debris source areas and also desk studies including Geographical Information System (GIS) applications and statistical assessments were performed. To justify the training data used in logistic regression analyses as representative, a random sampling procedure was applied. By using the results of the logistic regression analysis, the debris source area probability map of the region is produced. However, according to the field experiences of the authors, the produced map yielded over-predicted results. The main source of the over-prediction is structural relation between the bedding planes and slope aspects on the basis of the field observations, for the generation of debris, the dip of the bedding planes must be taken into consideration regarding the slope face. In order to eliminate this problem, in this study, an approach has been developed using probability distribution of the aspect values. With the application of structural adjustment, the final adjusted debris source area probability map is obtained for the study area. The field observations revealed that the actual debris source areas in the field coincide with the areas having high probability values on this final map. [ABSTRACT FROM AUTHOR]

Kat County, which is located in a slope of hilly region and constructed in the side of a mountain along the North Anatolian Fault Zone, is frequently subject to landslides. The slides occur during periods of heavy rainfall, and these events cause destruction to property, roads, agricultural lands and buildings. In the last few decades, a lot of houses and buildings have been damaged and destroyed. Settlement areas have remained evacuated for a long time. The slope instabilities in the study area are a complex landslide extending from north to south containing a lot of landslides. Field investigations, interpretation of aerial photography, analyses of geological data and laboratory tests suggest that some factors have acted together on the slopes to cause the sliding. In the wet season, the slopes became saturated. As the saturation of the earth material on the slope causesa rise in water pressure, the shear strength (resisting forces) decreases and the weight (driving forces) increases; thus, the net effect was to lower the safety factor. Previous failures have affected the rock mass, leading to the presence of already sheared surfaces at residual strengths. The relation between the joint planes and the instability of the slope in the study area was discussed and it was found that the potential slope instabilities are mainly in the directions of NW–SE, NE–SW and N–S. The landslide susceptibility map obtained by using the geographical information system showed that a large area is susceptible and prone to landslides in the northern part of the study area. [ABSTRACT FROM AUTHOR]

Koyulhisar located in a slope of hilly region and constructed in the side of a mountain along the North Anatolian Fault Zone is frequently subject to landslides. A catastrophic landslide occurred on the morning of 17 March 2005 in the North of the Kuzulu district of Koyulhisar (Sivas, Turkey). This landslide caused widespread loss of life, and damage to buildings, and lifelines. Fifteen people were dead and five were injured, 21 houses and a minaret were covered and damaged severely. The case study presented in this paper describes and analyses the results of the detailed surveys of an interesting landslide in Kuzulu district of Koyulhisar (Sivas, Turkey), based on field and laboratory measurements and monitoring of the slide area. Landslide initiated as a collapse, and developed into debris avalanches in the valley. This phenomenon caused a disaster in the Kuzulu district. The importance of this landslide in particular has been recognized both in terms of its consequence for the people and structures and in terms of its role in allowing an understanding of process and properties of landslide triggered by a collapse in limestone karst. In view of the potential for such events to occur again in this area and environs, understanding of the failure mechanism is very crucial. [ABSTRACT FROM AUTHOR]

Abstract: Landslides are common natural hazards in the seismically active North Anatolian Fault Zone of Turkey. Although seismic activity, heavy rainfall, channel incisions, and anthropogenic effects are commonly the main triggers of landslides, on March 17, 2005, a catastrophic large landslide in Sivas, northeastern of Turkey, the Kuzulu landslide, was triggered by snowmelt without any other precursor. The initial failure of the Kuzulu landslide was rotational. Following the rotational failure, the earth material in the zone of accumulation exhibited an extremely rapid flow caused by steep gradient and high water content. The Agnus Creek valley, where Kuzulu village is located, was filled by the earth-flow material and a landslide dam was formed on the upper part of Agnus Creek. The distance from the toe of the rotational failure down to the toe of the earth flow measured more than 1800 m, with about 12.5 million m3 of displaced earth material. The velocity of the Kuzulu landslide was extremely fast, approximately 6 m/s. The main purposes of this study are to describe the mechanism and the factors conditioning the Kuzulu landslide, to present its environmental impacts, and to produce landslide-susceptibility maps of the Kuzulu landslide area and its near vicinity. For this purpose, a detailed landslide inventory map was prepared and geology, slope, aspect, elevation, topographic-wetness index and stream-power index were considered as conditioning factors. During the susceptibility analyses, the conditional probability approach was used and a landslide-susceptibility map was produced. The landslide-susceptibility map will help decision makers in site selection and the site-planning process. The map may also be accepted as a basis for landslide risk-management studies to be applied in the study area. [Copyright &y& Elsevier]

Preparation of landslide susceptibility maps is important for engineering geologists and geomorphologists. However, due to complex nature of landslides, producing a reliable susceptibility map is not easy. For this reason, many procedures have been used to produce such maps. In this study, a new attempt is tried to produce landslide susceptibility map of a part of West Black Sea Region of Turkey. To obtain the fuzzy relations for producing the susceptibility map, a landslide inventory database is compiled by both field surveys and airphoto studies. A total of 266 landslides are identified in the study area, and dominant mode of failure is rotational slide while the other mode of failures are soil flow and shallow translational slide. The landslide inventory and the parameter maps are analyzed together using a computer program (FULLSA) developed in this study. The computer program utilizes the fuzzy relations and produces the landslide susceptibility map automatically. According to this map, 9.6% of the study area is classified as very high susceptibility, 10.3% as high susceptibility, 8.9% as moderate susceptibility, 27.5% as low susceptibility and 43.8% as very low susceptibility or nonsusceptible areas. The prediction performance of the susceptibility map is checked by considering actual landslides in the study area. For this purpose, strength of the relation (rij) and the root mean square error (RMSE) values are calculated as 0.867 and 0.284, respectively. These values show that the produced landslide susceptibility map in the present study has a sufficient reliability. It is believed that the approach employed in this study mainly prevents the subjectivity sourced from the parameter selection and provides a support to improve the landslide susceptibility mapping studies. [Copyright &y& Elsevier]

Following a period of heavy precipitation, a large and complex mass movement, namely the Şerefiye landslide, occurred in the Black Sea region of northern Turkey on 23 June 2000. This paper describes the conditioning factors of the landslide and interprets the mass transport processes. Geology, geomorphology and tectonics were considered as the conditioning factors of the failure. Observations showed that the sloping (c.9°) area is not covered by forest trees at the crown where the motion initiated. Analysis of the hydrological response of slopes during the rainstorm indicated that the majority of the failures were caused by the development of a perched water table in the thin surface layer of clay origin, due to infiltration during heavy rain. The distance from the crown down to the toe of the landslide was measured at more than 50 m. The landslide has block sliding characteristics in the upper portions and a debris flow/soil flow component around the margins of the sliding blocks in the middle parts and at the toe. The movement was initiated near the crown as a result of the excess water content between the main formation and the clay at the end of three days of heavy rainfall. The early perturbations lasted for five to six hours, after which the central part of the zone started to move as a soil flow, in which very large intact blocks were transported. Even though the movement was very rapid (1.2 m/min), there was no loss of life. However, the movement closed the road link between Sinop and Ayancık. [ABSTRACT FROM AUTHOR]

In the last decades, landslide hazard assessment has attracted many researchers'' attention. A number of parameters are suggested to be responsible to quantitatively explain the mechanism of landslides; many of these parameters are very important and factual. However, some data types and models are site-specific and could not be applied to different locations. Furthermore, the data stored in continuous parameter maps are divided into a number of classes arbitrarily, depending on the vision of the expert. Basically, this division controls the result of bivariate analysis. Besides, the responsible portion of the parameter map controlling the mechanism is also weighted arbitrarily. Based on these two facts, the class boundaries put a prejudice on the produced susceptibility/hazard maps, which result in dependence on the knowledge of the user rather than being dependent on the data and the fact itself. The aim of this study is to refine the previously defined methods in a more data-dependent trend. To achieve this goal, two new concepts: seed cells and percentile maps are introduced. Seed cells are the zones that are considered to represent the best undisturbed morphological decision rules (conditions before landslide occurs) and would be achieved by adding a buffer zone to the crown and flank areas of the landslide. To quantitatively classify the input parameter maps, the data distributions of seed cells in the parameter maps are divided into a number of classes on the basis of their distribution''s percentile break-points upon which the parameter maps are directly dependent on the seed cell distributions, hence to the data itself. [Copyright &y& Elsevier]

The aim of this study is to form a dynamic deformation model for landslides. Static and kinematic models used in practice in determining movements do not deal with the mechanical characteristics of the object and the deformation mechanism. They may yield misleading results in interpreting movements. In contrast, dynamic deformation models determine movements regarding the mechanical characteristics of the object and the deformation mechanism. In this study, a dynamic model reflecting the effect of the cause of movement for landslides was used for determining movements. For this purpose, the modeling of the effect of heavy rainfall and large underground water level changes in activating landslides was investigated. A test network was established in a slide area in Ma[cee_with_cedilla]ka County in the province of Trabzon in the northeast of Turkey. The coordinates of network points were computed with geodetic measurements. Underground water levels of the network points were determined with geological and geophysical measurements. Using these data, movements were determined with both kinematic and dynamic models. Results of both models were compared to each other. It was concluded that determining movements with the dynamic model was more suitable than using the kinematic model in landslide studies. It was also concluded that, regarding the difficulties in its construction, the dynamic model should be preferred in cases where human life is in serious danger. As another result of this study, it is shown that before interpreting movements of network points, it is necessary to detect slip surfaces on the study area and then perform the interpretation according to these slip surfaces. [ABSTRACT FROM AUTHOR]

Recently, numerous landslides occurred in the northern part of Koyulhisar. In 1998 and 2000, which were very wet years, landslides in different masses affected the geological formations which are well known for being prone to slope movements. Detailed geological, geomorphological and geotechnical surveys were carried out, and stability conditions in Koyulhisar village, located NE of Sivas (Turkey), are discussed in this paper. Kinematical analyses showed that the potential slope instabilities are in two main directions: the first direction is SE and the second is SW, these directions corresponding to the dominant slope directions of the study area. Geomechanic surveys confirmed that most of the rock slopes analysed are highly prone to instability. The SMR criterion gave results which correspond well with real stability conditions. Jointing and faulting, steep topography, water incisions, and heavy rainfall played a significant role in the occurrence of the landslides. [ABSTRACT FROM AUTHOR]

Regional landslide susceptibility assessments pose complex problems. To solve these problems, numerous approaches, such as statistical analysis, geotechnical engineering approach, geomorphologic approach and fuzzy logic, have been employed. However, all the available methods for regional landslide susceptibility assessments have some uncertainties due to a lack of knowledge and variability. Minimizing these uncertainties provides realistic approaches. Use of the fuzzy logic approach to produce a landslide susceptibility map of a landslide-prone area in NW Turkey is the main purpose of the present study. For this purpose, the study includes five main stages, these being the preparation of a landslide inventory of the study area, the application of factor analysis, the extraction of fuzzy if-then rules, the use of a geographical information system, and the control of the reliability of the resulting landslide susceptibility map. Slope angle, slope aspect, land use, weathering depth, water conditions and topographical elevation were considered as landslide conditioning factors for the study area. A total of 23 if-then rules was extracted from the field data. Employing these rules, fuzzified index maps representing each parameter were obtained. Finally, combining these maps, the landslide susceptibility map of the area was prepared. When compared with the landslide susceptibility map, the landslides identified in the area were found to be located in the very high- and high-susceptibility zones. As far as the performance of the fuzzy approach for processing is concerned, the images appear to be quite satisfactory, the zones determined on the map being zones of relative susceptibility. [ABSTRACT FROM AUTHOR]

The study area is located in the south of İzmir city centre in an area built without planning permission or any overall city plan. In this area, a number of mass movements occurred in the past and the region is still an active landslide field at present. The real sliding factor is geological structure, which is made up of hard volcanic rocks overlying soft Neogene clayey soils, and forms a typical structure prone to sliding. Unplanned human activities change the hydrogeological and geotechnical stabilities of the geological formations in a negative way. Rain and water leaking either directly from the mains or septic holes infiltrate into the ground and act as one of the factors in causing landslides. It is clearly shown that the irregular urbanization in and around Kadifekale is one of the factors contributing to the landslides in the area. To prevent the occurrence of landslides in the study area an effective surface and under ground drainage should be established. Rain and wastewater should be removed from the area by separate systems. Slopes should be reduced, water-loving trees should be planted and construction of high rise buildings should be avoided. [ABSTRACT FROM AUTHOR]