Micro-Tremor Induced Gravity and Seismic Noise Spectra in the Garhwal Himalaya and the Adjoining Regions

The characteristic site response spectra of soft sedimentary rocks in the Garhwal Himalaya and a few localities in the adjoining Ganga plain and Himachal Himalaya have been studied through short period passive seismic source experiment using ambient noise data. Along with this, stand-alone temporal gravity data in the Doon valley was also acquired. It has been observed that there exist two extreme frequency bands in the gravity and seismic response spectra of alluvial soft sediments in the Doon valley and the adjoining regions, when it subjected to micro-seismic and gravity-tidal oscillation. The concept of damped harmonic oscillator was used to study the fundamental long period modes in the density driven diffusive fluid flow in the valley alluvial pore spaces, and observed that the flow was continued from minutes to a few days. In this case, apart from the diurnal component, the observed fundamental modes are in the bands from 0.42 to 1.83 days. The characteristic frequencies of seismic response spectra for the fundamental modes of thick soft sediments were also studied using the spectral ratio (HVSR) method of Nakamura. In the Ganga basin, a moderate resonant frequency of 3 Hz is sufficient for thick soft sediment to cause relatively large vertical amplitude, which suggest possibility for sub-surface secondary seismic effects like liquefaction. However, the hard rock terrains in the lesser Himalaya, where only a veneer of soft sediment is present, show relatively high frequency values of 15 to 18 Hz even to produce an H/V amplitude ratio of 1 and 1.7 and hence could be considered as relatively stable.     

Seismic hazard and probability assessment of Kashmir valley,northwest Himalaya,India

Seismic hazard analysis of the northwest Himalayan belt was carried out by using extreme value theory (EVT). The rate of seismicity (a value) and recurrence intervals with the given earthquake magnitude (b value) was calculated from the observed data using Gutenberg–Richter Law. The statistical evaluation of 12,125 events from 1902 to 2017 shows the increasing trend in their inter-arrival times. The frequency–magnitude relation exhibits a linear downslope trend with negative slope of 0.8277 and positive intercept of 4.6977. The empirical results showed that the annual risk probability of high magnitude earthquake M?≥?7.7 in 50 years is 88% with recurrence period of 47 years, probability of M?≤?7.5 in 50 years is 97% with recurrence period of 27 years, and probability of M?≤?6.5 in 50 years is 100% with recurrence period of 4 years. Kashmir valley, located in the NW Himalaya, encompasses a peculiar tectonic and structural setup. The patterns of the present and historical seismicity records of the valley suggest a long-term strain accumulation along NNW and SSE extensions with the decline in the seismic gap, posing a potential threat of earthquakes in the future. The Kashmir valley is characterized by the typical lithological, tectono-geomorphic, geotechnical, hydrogeological and socioeconomic settings that augment the earthquake vulnerability associated with the seismicity of the region. The cumulative impact of the various influencing parameters therefore exacerbates the seismic hazard risk of the valley to future earthquake events.     

Microstructures and evolution of folds in SC-mylonites from Dudatoli-Almora crystallines of Garhwal Himalaya

In the Lesser Garhwal Himalaya, the North Almora Thrust separates the overlying medium-grade Dudatoli-Almora crystallines of Precambrian age from the unmetamorphosed to partly metamorphosed rocks of the Garhwal Group of Late Precambrian age. The crystalline nappe sheet consists of flaggy to schistose quartzites, granite gneisses and garnetiferous mica schist members in an ascending order. In different localities. different members of the Dudatoli-Almora crystallines are exposed along the thrust plane. Southwest of Adbadri fine-grained mylonitized schistose quartzites of Dudatoli-AImora crystallines are in contact with the underlying metabasites of the Garhwal Group. The mylonitized schistose quartzites consist of alternating thick (1 to 2m) quartzite and thin (10 to 20cm) micaceous quartzite bands. The micaceous quartzites can be further differentiated into alternating quartz-rich (0-5 to 2.0 cm thick) and mica-rich (0.2 to 1.0 cm thick) layers. In the quartzites the C-surfaces are parallel to the S-surfaces defined by the alternating quartz-rich and mica-rich layers. Further, the S-surfaces exhibit almost similar folds with multiple wavelengths where the axial planes are nearly parallel and enveloping surfaces are oblique to the lithological layering. The evolution of these folds has been envisaged in three phases of deformation on the basis of field evidence, fold geometry and microstructures. During the first phase buckle folds (F ₁) developed in thin micaceous quartzite layers. whereas thick quartzite bands underwent only layer parallel shortening. During the second phase the stress orientation changed and the limbs ofF ₁ folds were folded (F ₂). During the third phase of deformation which coincided with thrusting, the rocks were sheared, mylonitized and developed microstructures exhibiting dynamic recrystallization by the processes of subgrain rotation, and continual and discontinuai grain boundary migration. This phase was also responsible for the development of C-surfaces parallel to the lithological layering. Further, in the folded micaceous quartzite layers shearing resulted in the development of C-surfaces parallel to the axial planes ofF ₂ folds.     

Mylonitic microfabrics from the rocks of MCT zone in Alakhnanda valley,Garhwal Himalaya

MCT Zone of Alakhnanda valley is a major ductile shear zone in Garhwal Himalaya, which is characterised by different types of mylonite rocks. On the basis of grain size and the percentage of matrix in the rock, zones comprising protomylonite, augen mylonite, mylonite and ultramylonite have been identified. The study of microstructures, grain size and crystallographic preferred orientation of quartz c-axis fabric reveals that the rocks of the MCT zone were deformed by a combination of intracrystalline creep (power law creep) and grain boundary migration (sliding super plasticity).     

Seismic hazard assessment using the theory of records

This article is a review of some basic results for analysis of records. First, the general methods appropriate for seismic hazard are discussed. Then, in view of the frequency-magnitude law of Gutenberg and Richter, some results relevant for hazard assessment related to earthquakes are presented. The discussion is concluded with an example of application and comparison with classical methods.     

Seismic hazard assessment in the Jia Bhareli river catchment in eastern Himalaya from SRTM-derived basin parameters,India

SRTM (Shuttle Radar Topographic Mission), Landsat ETM+ satellite image analysis along with earthquake data in the Jia Bhareli river catchment, an eastern Himalayan tributary of the Brahmaputra indicates neotectonic activities in the region. We have envisaged from the study that the western part of the river catchment (western tectonic domain) is highly tectonically active as indicated by earthquake data, and SRTM DEM-derived longitudinal profiles, valley profiles, valley asymmetry, hypsometric integral values. On the other hand, the eastern part of the catchment has no sign of such active tectonics (eastern tectonic domain) except the south convex fan-shaped zone further east with linear ridges paralleling the convex shape deforming the Miocene–Pleistocene Siwalik sediments and the Quaternary piedmont deposits in the Himalayan foothills. The catchment seems tilting to the east due to the ongoing tectonic activities propagating the deformational activities, generating folded structures, to the east and yielding earthquakes due to rigid deformation in the western part of the catchment. From the study, seismic risk in the south–central part of eastern Himalayas around Bomdila in the state of Arunachal Pradesh appears to be high.     

Structure and petrology of mylonite and related rocks from the Lesser Himalaya,Garhwal, India

In the Lesser Himalayan region of Garhwal, an elongate, NW-SE trending zone of mylonitic rocks is developed along the Singuni Thrust within the metasedimentary formation of the Deoban-Tejam Belt. Detailed petrography of various mylonitic rocks indicates that a quartz and felspar porphyry was emplaced along the Singuni Thrust. This was initially metamorphosed in the almandine-amphibolite facies before profound ruptural or cataclastic and crystalloblastic deformation evolved mylonitic rocks in the green schist facies. Southwesterly dipping foliation and an equally prominent mica lineation plunging in the same direction are developed in these mylonitic rocks. The quartzite is also intensely cataclastically deformed in the green schist facies and is highly schistose with a prominent mica lineation normal to the trace of Singuni Thrust, Uttarkashi Thrust and Main Central Thrust in the ‘a’ direction of tectonic transport. In quartzite and mylonitic rocks, a probable contemporaneous development of the metamorphic and structural elements has been postulated along the Singuni Thrust during large scale tectonic movements. Normally exposed Gamri Quartzite is more metamorphosed near its base along the Singuni Thrust and Uttarkashi Thrust while the intensity of deformation increases near the top of normally exposed quartzite along the Main Central Thrust and, thus, signifying the role of thrusting in cataclastically deforming the rocks and contributing to the phenomenon of widespread reversal of metamorphism in the Lesser Himalaya.     

Seismic hazard and site-specific ground motion for typical ports of Gujarat

Economic importance of major ports is well known, and if ports are located in seismically active regions, then site-specific seismic hazard studies are essential to mitigate the seismic risk of the ports. Seismic design of port sites and related structures can be accomplished in three steps that include assessment of regional seismicity, geotechnical hazards, and soil structure interaction analysis. In the present study, site-specific probabilistic seismic hazard analysis is performed to identify the seismic hazard associated with four typical port sites of Gujarat state (bounded by 20°–25.5°N and 68°–75°E) of India viz. Kandla, Mundra, Hazira, and Dahej ports. The primary aim of the study is to develop consistent seismic ground motion for the structures within the four port sites for different three levels of ground shaking, i.e., operating level earthquake (72 years return period), contingency level earthquake (CLE) (475 year return period), and maximum considered earthquake (2,475 year return period). The geotechnical characterization for each port site is carried out using available geotechnical data. Shear wave velocities of the soil profile are estimated from SPT blow counts using various empirical formulae. Seismicity of the Gujarat region is modeled through delineating the 40 fault sources based on the seismotectonic setting. The Gujarat state is divided into three regions, i.e., Kachchh, Saurashtra, and Mainland Gujarat, and regional recurrence relations are assigned in the form of Gutenberg-Richter parameters in order to calculate seismic hazard associated with each port site. The horizontal component of ground acceleration for three levels of ground shaking is estimated by using different ground motion attenuation relations (GMAR) including one country-specific GMAR for Peninsular India. Uncertainty in seismic hazard computations is handled by using logic tree approach to develop uniform hazard spectra for 5% damping which are consistent with the specified three levels of ground shaking. Using recorded acceleration time history of Bhuj 2001 earthquake as the input time motion, synthetic time histories are generated to match the developed designed response spectra to study site-specific responses of port sites during different levels of ground shaking. It is observed that the Mundra and Kandla port sites are most vulnerable sites for seismic hazard as estimated CLE ground motion is in order of 0.79 and 0.48 g for Mundra and Kandla port sites, respectively. Hazira and Dahej port sites have comparatively less hazard with estimated CLE ground motion of 0.17 and 0.11 g, respectively. The ground amplification factor is observed at all sites which ranges from 1.3 to 2.0 for the frequency range of 1.0–2.7 Hz. The obtained spectral accelerations for the three levels of ground motions and obtained transfer functions for each port sites are compared with provisions made in Indian seismic code IS:1893-Part 1 (2002). The outcome of present study is recommended for further performance-based design to evaluate the seismic response of the port structures with respect to various performance levels.     

Geomorphological evidences of post-LGM glacial advancements in the Himalaya: A study from Chorabari Glacier,Garhwal Himalaya,India

Field geomorphology and remote sensing data, supported by Optical Stimulated Luminescence (OSL) dating from the Mandakini river valley of the Garhwal Himalaya enabled identification of four major glacial events; Rambara Glacial Stage (RGS) (13 ± 2 ka), Ghindurpani Glacial Stage (GhGS) (9 ± 1 ka), Garuriya Glacial Stage (GGS) (7 ± 1 ka) and Kedarnath Glacial Stage (KGS) (5 ± 1 ka). RGS was the most extensive glaciation extending for ~6 km down the valley from the present day snout and lowered to an altitude of 2800 m asl at Rambara covering around ~31 km² area of the Mandakini river valley. Compared to this, the other three glaciations (viz., GhGS, GGS and KGS) were of lower magnitudes terminating around ~3000, ~3300 and ~3500 m asl, respectively. It was also observed that the mean equilibrium line altitude (ELA) during RGS was lowered to 4747 m asl compared to the present level of 5120 m asl. This implies an ELA depression of ~373 m during the RGS which would correspond to a lowering of ~2°C summer temperature during the RGS. The results are comparable to that of the adjacent western and central Himalaya implying a common forcing factor that we attribute to the insolation-driven monsoon precipitation in the western and central Himalaya.     

Earthquake hazard zonation of Sikkim Himalaya using a GIS platform

An earthquake hazard zonation map of Sikkim Himalaya is prepared using eight thematic layers namely Geology (GE), Soil Site Class (SO), Slope (SL), Landslide (LS), Rock Outcrop (RO), Frequency–Wavenumber (F–K) simulated Peak Ground Acceleration (PGA), Predominant Frequency (PF), and Site Response (SR) at predominant frequencies using Geographic Information System (GIS). This necessitates a large scale seismicity analysis for seismic source zone classification and estimation of maximum earthquake magnitude or maximum credible earthquake to be used as a scenario earthquake for a deterministic or quasi-probabilistic seismic scenario generation. The International Seismological Center (ISC) and Global Centroid Moment Tensor (GCMT) catalogues have been used in the present analysis. Combining b-value, fractal correlation dimension (Dc) of the epicenters and the underlying tectonic framework, four seismic source zones are classified in the northeast Indian region. Maximum Earthquake of M _W 8.3 is estimated for the Eastern Himalayan Zone (EHZ) and is used to generate the seismic scenario of the region. The Geohazard map is obtained through the integration of the geological and geomorphological themes namely GE, SO, SL, LS, and RO following a pair-wise comparison in an Analytical Hierarchy Process (AHP). Detail analysis of SR at all the recording stations by receiver function technique is performed using 80 significant events recorded by the Sikkim Strong Motion Array (SSMA). The ground motion synthesis is performed using F–K integration and the corresponding PGA has been estimated using random vibration theory (RVT). Testing for earthquakes of magnitude greater than M _W 5, a few cases presented here, establishes the efficacy and robustness of the F–K simulation algorithm. The geohazard coverage is overlaid and sequentially integrated with PGA, PF, and SR vector layers, in order to evolve the ultimate earthquake hazard microzonation coverage of the territory. Earthquake Hazard Index (EHI) quantitatively classifies the terrain into six hazard levels, while five classes could be identified following the Bureau of Indian Standards (BIS) PGA nomenclature for the seismic zonation of India. EHI is found to vary between 0.15 to 0.83 quantitatively classifying the terrain into six hazard levels as “Low” corresponding to BIS Zone II, “Moderate” corresponding to BIS Zone III, “Moderately High” belonging to BIS Zone IV, “High” corresponding to BIS Zone V(A), “Very High” and “Severe” with new BIS zones to Zone V(B) and V(C) respectively.     

Seismic hazard map of Coimbatore using subsurface fault rupture

This study presents the future seismic hazard map of Coimbatore city, India, by considering rupture phenomenon. Seismotectonic map for Coimbatore has been generated using past earthquakes and seismic sources within 300 km radius around the city. The region experienced a largest earthquake of moment magnitude 6.3 in 1900. Available earthquakes are divided into two categories: one includes events having moment magnitude of 5.0 and above, i.e., damaging earthquakes in the region and the other includes the remaining, i.e., minor earthquakes. Subsurface rupture character of the region has been established by considering the damaging earthquakes and total length of seismic source. Magnitudes of each source are estimated by assuming the subsurface rupture length in terms of percentage of total length of sources and matched with reported earthquake. Estimated magnitudes match well with the reported earthquakes for a RLD of 5.2% of the total length of source. Zone of influence circles is also marked in the seismotectonic map by considering subsurface rupture length of fault associated with these earthquakes. As earthquakes relive strain energy that builds up on faults, it is assumed that all the earthquakes close to damaging earthquake have released the entire strain energy and it would take some time for the rebuilding of strain energy to cause a similar earthquake in the same location/fault. Area free from influence circles has potential for future earthquake, if there is seismogenic source and minor earthquake in the last 20 years. Based on this rupture phenomenon, eight probable locations have been identified and these locations might have the potential for the future earthquakes. Characteristic earthquake moment magnitude (M _w ) of 6.4 is estimated for the seismic study area considering seismic sources close to probable zones and 15% increased regional rupture character. The city is divided into several grid points at spacing of 0.01° and the peak ground acceleration (PGA) due to each probable earthquake is calculated at every grid point in city by using the regional attenuation model. The maximum of all these eight PGAs is taken for each grid point and the final PGA map is arrived. This map is compared to the PGA map developed based on the conventional deterministic seismic hazard analysis (DSHA) approach. The probable future rupture earthquakes gave less PGA than that of DSHA approach. The occurrence of any earthquake may be expected in near future in these eight zones, as these eight places have been experiencing minor earthquakes and are located in well-defined seismogenic sources.     

High-Field Strength Element Geochemistry of Mafic Intrusive Rocks from the Bhagirathi and Yamuna Valleys,Garhwal Himalaya,India

Incompatible high-field strength element geochemistry divides mafic intrusive rocks of Garhwal Himalaya, exposed in the Bhagirathi and Yamuna valleys, into two distinct types, viz. older Garhwal Mafic Intrusive Rocks (GMIR1) and younger Garhwal Mafic Intrusive Rocks (GMIR2). GMIR1 is mainly associated with the Central Crystallines, whereas, GMIR2 belongs to the Garhwal Group. They outcrop close to the Main Central Thrust (MCT) Zone and extend in a NW-SE direction, following the strike direction. Both types are metamorphosed to amphibolite facies and classified as sub-alkaline, high-Fe tholeiitic basalts. They are enriched in large-ion lithophile and high-field strength elements relative to a primitive mantle source. GMIR2 has higher concentrations of incompatible high-field strength elements than the GMIR1. Further, on multi-element spidergrams, GMIR1 samples do not show any elemental anomaly but GMIR2 samples show distinct negative Nb and Sr anomalies. GMIR1 multi-element and rare-earth element trends are similar to N-MORB, whereas, GMIR2 follows trends observed in the within plate basalts (continental flood basalts type). Discrimination diagrams, based on incompatible trace elements, corroborate the N-MORB nature of GMIR1 and CFB (WPB) nature of GMIR2. Geochemical modeling indicates that these mafic intrusive rocks were derived by close-system fractional crystallization of depleted (for GMIR1) to variably enriched parental basalts (for GMIR2). Probably these two contrasting mafic rock types have been juxtaposed during the Himalayan orogeny. Proterozoic mafic rocks of similar geochemical characteristics have been reported from different parts of the northern Indian lithosphere. Observed composition suggests its genetic association with the sub-continental lithosphere rather than effect of crustal contamination.     

Petrography,geochemistry and regional significance of crystalline klippen in the Garhwal Lesser Himalaya,India

Uphalda gneisses (UG) is a crystalline klippe located near Srinagar in Garhwal Himalaya. These gneisses are compared with Debguru porphyroids (DP) (≈Ramgarh group) of Garhwal–Kumaun Himalaya and Baragaon mylonitic gneisses (BMG) of Himachal Himalaya. Petrographic study reveals that the deformation of UG was initiated at higher temperature (above 350°C) and continued till lowering of temperature and deformation led to the mylonitization.     

从宽角地震数据得出的特提斯喜马拉雅南部的速度结构

作为ＩＮＤＥＰＴＨ计划的第一阶段，完成了一条跨过特提斯喜马拉雅南缘的深地震共中点（ＣＭＰ）剖面，它绘制出俯冲到喜马拉雅之下的印度大陆地壳的顶部（主喜马拉雅道冲或ＭＨＴ）和底部（莫霍层）轮廓。我们用移动式地震仪记录了ＣＭＰ剖面的爆炸，偏移距最大达１５５ｋｍ。短偏移距数据证实了ＣＭＰ剖面的数据，而我们的大偏移距数据则以强反射带为主。我们将这一反射带的强的初始相位解释为藏南滑脱系（ＳＴＤ），而其最后一个相位则为ＭＨＴ的反映。我们用ＣＭＰ剖面的初动数据去详细地模拟最上部２ｋｍ的结构。亚东裂谷系中年青的伸展盆地的深度约束在２ｋｍ，给出了裂谷东侧的断距为４．６ｋｍ，在特提斯喜马拉雅内的正断层，Ｅ－Ｗ向伸展１．５％。宽角数据用于建立地表到ＭＨＴ的地震波速度模型。ＳＴＤ反射体北倾１３°，从约６ｋｍ深（在ＣＭＰ剖面南端之下）到２２ｋｍ深，然后变平，倾角减至５°。这样，我们的观测提出ＳＴＤ是一个深的基底断裂，对ＭＨＴ，我们观测到倾角为７５°，ＮＮＥ倾，从高喜马拉雅山脊下的－２０ｋｍ海拔到雅鲁藏布江缝合带南约７０ｋｍ处的－３６ｋｍ海拔（地表下４０ｋｍ）。我们提出印度地壳可能俯冲到缝合带地表之下，却不可能是整体俯冲。     

Microstructures and strain variation across the footwall of the Main Central Thrust Zone,Garhwal Himalaya,India

The microstructural variation with a progressive change in the strain pattern are described in the rocks occurring across the footwall of the Main Central Thrust (MCT) in an area of the Garhwal Himalaya. In the western Garhwal Himalaya, the MCT has brought upper amphibolite facies metamorphic rocks southward over the greenschist facies rocks of the Lesser Himalaya. The progressively increasing flattening strain towards the MCT changes either to plane strain or in some cases to constrictional strain. This change in strain is well recorded in the microstructures. The zone dominated by flattening strain is expressed as bedding parallel mylonites. The grain reduction in this zone has occurred by dynamic recrystallization and quartz porphyroclasts were flattened parallel to the mylonite zone. The maximum finite strain ratio observed in this zone is 2.2:1.8:1. The zone, where the flattening strain changes either to plane strain or constrictional strain, record an increase in finite strain ratio up to 3.8:1.9:1. This zone represents deformation fabrics like S–C microstructures simultaneously developed during mylonitization in an intense ductile shear zone. The above zone is either near the MCT or adjacent to crystalline klippen occupying the core of the synforms in the footwall of the MCT. The microstructural evolution and the finite strain suggest that the MCT has evolved as the result of superposition of southward directed simple shear over the flattening strain. The simple shear has played an active role in the rapid translation which followed the mylonitization at deeper levels.     

Seismic random noise attenuation using artificial neural network and wavelet packet analysis

In this paper, we present a method for attenuating background random noise and enhancing resolution of seismic data, which takes advantage of semi-automatic training of feed forward back propagation (FFBP) artificial neural network (ANN) in a multiscale domain obtained from wavelet packet analysis (WPA). The images of approximations and details of the input seismic sections are calculated and utilized to train neural network to model coherent events by an automatic algorithm. After the modeling of coherent events, the remainder data are assumed to be related to background random noise. The proposed method is applied on both synthetic and real seismic data. The results are compared with that of the adaptive Wiener filter (AWF) in synthetic shot gather and real common midpoint gather and also with that of band-pass filtering on real common offset gather. The comparison indicates substantially higher efficiency of the proposed method in attenuating random noise and enhancing seismic signals.     

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.     

Seismic hazard analysis of Mersin Province,Turkey using probabilistic and statistical methods

Nearly 108-km lengths of Mersin shores are composed of natural beaches. The region is located between major tourist centers. In the future, this region is thought to be built with a great number of tourist facilities. Turkey’s largest seaport, Ata? refinery (Mersin International Port) is located in Mersin. Recently, Mersin is becoming of great importance to Turkey as the latter plans to construct its second nuclear power plant in the region. Therefore, as nuclear power plants are built to withstand environmental hazards, it is very important to analyze the seismic risk of the areas where the nuclear power plant will be constructed. The region is located between the East Anatolian Fault Zone and Center Anatolian Fault Zone. Based on the Turkey Earthquake Regions Map, Mersin is divided into second-, third-, and fourth-degree earthquake regions. In this study, we sampled earthquakes of magnitude of 4.0 or greater between 01 Jan 1900 and 31 Dec 2010 in the area; seismic hazard of Mersin province was estimated with probabilistic and statistical methods. The study area was selected as the coordinates between 36.03° and 37.42° North and 32.57° and 35.16° East. On the study area, different scaled magnitude values in the last 110 years converted to a common scale (Mw) and earthquake catalog was re-compiled and also seismic sources that may affect the area was determined. In this study, the seismic hazards of the region were obtained using the methods of probability and statistics. This study used three different attenuation relationships. Using the attenuation relationships suggested by Boore et al. (Seismol Res Lett 68(1):128–153, 1997) and Kalkan and Gülkan (Earthquake Spectra 20:1111–1138, 2004), the largest ground acceleration which corresponds to a recurrence period of 475 years was found as 0.08–0.09 g and Akkar and Ça?nan (Bull Seismol Soc Am 100 6:2978–2995, 2010), 0.04 g for bedrock at the central district. When computing for seismic hazard curves, Mut district appears to have a greater seismic hazard compared with other districts. Moreover, according to the attenuation relationships, seismic hazard curves corresponding to a recurrence period of 475 years were obtained for the Mersin Central, Mut, Erdemli, Çaml?yayla, and Tarsus districts.     

DEM-based deterministic landslide hazard analysis in the Lesser Himalaya of Nepal

In Nepal, people live in widely spread settlements in the fragile Himalayan terrains, and suffer more from landslides than from any other type of natural disaster. The small-scale rainfall-triggered landslides in the Lesser Himalaya of Nepal are generally shallow (about 0.5 to 2.5 m) and are triggered by changes in the physical property of soil layers during rainfall. The relation between landslides and slope hydrology has received little attention in Himalayan landslide research. Thus, this paper deals with the probability of slope failure during extreme rainfall events by considering a digital elevation model (DEM)-based hydrological model for soil saturation depth and an infinite slope stability model. Deterministic distributed analysis in a geographic information system (GIS) was carried out to calculate the probability of slope failure. A simple method of error propagation was used to calculate the variance of the safety factors and the probability of failure. When normally distributed failure probability values were checked against existing landslides, it was found that more than 50% of the pixels of existing landslides coincided with a high calculated probability of failure. Although the deterministic distributed analysis has certain drawbacks, as described by previous researchers, this study concluded that the calculated failure probability can be utilised to predict the probability of slope failure in Himalayan terrain during extreme rainfall events.