The 2.5D crustal density structure is modelled using complete Bouguer anomaly along two W-E profiles across the Marwar block, Aravalli-Delhi Fold Belt (ADFB), and the Bundelkhand craton, constituting the north-western edge of the Indian Shield. The rock density closely mimics the litho-tectonic units that preserve the Archean-Proterozoic evolutionary history. The Bouguer anomaly along the profiles, corresponds to significant variation in crustal structure, with Moho depth varying from 34 to 40 km under the Marwar block, similar to 45 km under high-relief ADFB and <42 km under the Bundelkhand craton. A high density (2.78 g/cm(3)) 6-8 km thick sill in the upper crust and a 10-12 km thick high-density (3.05 g/cm(3)) body as the mantle underplating at the Moho, represent the source conduit of the Neoproterozoic Malani Igneous Suite in the Marwar block. The significant lithological variation within the 8-10 km thick upper crust with a 12-13 km thick elongated high-density (3.05 g/cm(3)) basaltic body with a diffused Moho signature, possibly representing the mantle underplating due to orogenic root delamination under the ADFB. The lateral variation in the crustal structure across the craton suggests the orogenic reworking during the early-mid Proterozoic and mantle upwelling in an extensional regime during the Neoproterozoic in the ADFB and Marwar lock.
This study employs seismic techniques for the site characterization of the Korba region in Chhattisgarh, India. Seismic activity has been reported in this region lately, classifying this region in seismic zone III, according to the Building Materials and Technology Promotion Council (BMTPC) assessment (2006). We gather data from 30 different locations in the Korba region, using the Tromino instrument. We estimate the fundamental frequency, construct shear wave velocity for subsurface classification of the Korba region, and develop Horizontal-to-Vertical Spectral Ratio (HVSR) curves for ambient noise data in accordance with the National Earthquake Hazards Reduction Programme (NEHRP) criteria. We calculated the liquefaction vulnerability index (Kg), amplification value, and peak resonant frequencies from the HVSR curve. Amplification factors range from 1.18 to 10.02, while the peak resonant frequencies span from 1.146 to 15.062 Hz. Vs30 for the region varies between 140.06 and 646.90 m/s. These findings indicate presence of soft soil in the western portion of the region, which is situated along the Hasdeo River's bank. In majority of the places, we discovered that the Kg value was less than 10, indicating low liquefaction vulnerability in the examined area.
Kutch rift basin situated in the northwestern part of the Deccan volcanic province, is characterised by sustained intermediate to deep crustal earthquake activity since historical times, unheard in other global stable terrains. This region underwent through several geotectonic, thermal and magmatic episodes in the past, whose signatures are manifested in various forms including the complex and heterogeneous crust-mantle velocity structure. In order to delineate hydrocarbon-rich Mesozoic sediments and underlying basement configuration, seismic refraction and wide-angle reflection data was acquired along the four Deep Seismic Sounding profiles. In the present study, we reprocessed the seismic data along one of these profiles, shot across the southwestern part of the Kutch region, that runs from Jakhau to Mandvi on the west coast. Our study delineated occurrence of a six-layered sequence above the granitic-gneissic basement (Vp: 5.90-6.00 km/s), with their thicknesses varying from 5.5 to 8 km. It includes, Tertiary sediments (Vp: 2.0 km/s), Deccan basalts (Vp: 4.70 km/s), upper low velocity Mesozoic sediments (Vp: 3.3 km/s), Mesozoic limestone (Vp : 5.1 km/s) followed by Mesozoic volcanics (Vp: 5.50 km/s) and another low velocity Mesozoic sediments (Vp: 5.30 km/s). It is underlain by mid-crustal layer (Vp: 6.30-6.40 km/s) located at depths of around 8 to 12.5 km, which is further underlain by a relatively thinner lower crustal layer (Vp: 6.80-6.90 km/s). Below this layer, we also delineated two distinct underplated magmatic layers (Vp: 7.20-7.50 km/s) above the Moho, characterize by velocity 7.7-8.0 km/s. Moho is delineated at an extremely shallow depths from 25 to 35 km. Conspicuously, we also depicted a frozen mantle magma chamber (Vp: 8.0 km/s), in the uppermost mantle, which coincides with the location of Katrol Hill Fault. It appears that this region has undergone persistent magmatism, massive subcrustal erosion and asthenospheric upwarping.
It is widely acknowledged that even when earthquakes occur inside a specific confined area, there can be significant variations in the focal mechanism solutions. Several earthquakes have been detected by broadband seismometers coupled with a digital recorder (Centaur) at six stations in the Himachal Himalaya during 2018-2019. Therefore, we addressed an approach for identifying the orientation of fault planes in the studied area. In this paper, we retrieved the fault plane solutions of 25 earthquakes using a double couple fault plane method, based on P-wave polarity readings and amplitude ratio with the help of the Seisan program. Earthquakes exhibit diverse fault plane solutions. From a total of 25 earthquakes, 3 show normal faulting, 19 show reverse faulting, and 3 show strike-slip mechanism. This is because rupture lengths for local events (M < 3.5) are typically in the range of a few hundred meters to a kilometer, and events may occur on faults with varying orientations. The maximum concentration of thrust faults is consistent with the trend of the Himalayan collisional zone and the location of major faults. Except for some showing a dip greater than 60 degrees, earthquakes with precisely measured depths characterise a zone from 0.1 25 km with an average dip of about 44.6 degrees. All focal mechanisms of events that are available within this zone, indicate a steeper dip. An earthquake that occurred near the Sundarnagar fault, shows a strike-slip mechanism. Based on this interpretation, there may be a genetic relationship between the Himalayan block above the MBT and a transverse structural feature in the underthrusting Indian plate (Sundarnagar fault). Earthquakes reveal a trend of directions concerning the T-axis and P-axis with all types of fault plane solutions.
Gorakhpur city, situated in the Indo-Gangetic Plain of northern India and classified under Seismic Zone IV, is increasingly getting vulnerable to earthquake-induced ground motion due to its proximity to active Himalayan belt, growing urban footprint and soft alluvial subsurface conditions. This study presents a comprehensive seismic hazard assessment based on key site parameters, including average shear wave velocity up to 30 m (Vs30), predominant frequency (f(0)), fundamental time period (T-0), peak amplification (A(0)), engineering bed rock depth (EBR) and the Seismic vulnerability index (Kg). Ambient noise data is used to estimate f(0) and A(0), while shear wave velocity profiles were obtained through study of Multichannel Analysis of Surface Waves (MASW). Spatial interpolation and GIS-based mapping of these parameters, reveal significant heterogeneity in the subsurface response characteristics. Zones with low Vs30, low f(0), longer T-0, high EBR, high A(0) and high Kg values, primarily in the southern parts of the city, demonstrating a high potential for ground motion amplification and structural resonance. The Kg index, effectively highlights the most seismically vulnerable zones within the city, while EBR is estimated using predominant frequency and shear wave velocity. The results underline the critical need for microzonation-based land use planning, earthquake-resilient construction, and site-specific design codes. This study provides essential input for seismic risk reduction and sustainable urban development in Gorakhpur, and establishes a framework for similar assessments in other seismically active regions of the Indo-Gangetic basin.
In this study, a Deep learning-based model, Stochastic Neural Network (SNN), which excels in handling uncertain and complex data, is customized to predict groundwater quality in the Kanyakumari District of Tamil Nadu (India), where groundwater is considered a critical source for drinking and agricultural purposes. The SNN model captures the stochastic nature of the data and provides reliable predictions by simulating multiple possible outcomes, making the model ideal for groundwater quality prediction. A range of groundwater quality indicators, such as pH, EC, TDS, etc. were used to train the model. Rainfall patterns were found to have a considerable impact on water quality over a ten-year period, emphasizing the importance to include seasonal data into prediction models. Hence, rainfall data was also included in order to evaluate its impact on groundwater quality. The deep learning model demonstrated its effectiveness with 95% prediction accuracy. The model's capacity to distinguish between classes was evaluated by the Classification Report, Receiver Operating Characteristic (ROC) curves, Area Under the Curve (AUC) values and the confusion matrix. In addition to this, Cross-validation (CV) was employed to confirm the model's performance and also to test the reliability of the results. This study provides an efficient method that can assist in sustainable use of groundwater resources.
The Kota-Pawalgarh Dun is a Half-Dun structure shaped by spatial variation in active deformation partitioning within the Main Boundary Thrust (MBT)-Himalayan Frontal Thrust (HFT) wedge in the Central Kumaun Himalayan front. The post-Siwalik Piedmont fans consist of Dun gravels and provide a geomorphic and stratigraphic constraint on the deformation partitioning on the Dun. Though the fans were mapped, the lack of ages failed to constrain the definition of their stratigraphic and structural significance in the Late Quaternary evolution of the Dun. We present the new mapping results using field and remote sensing data with chronological constraints from the Optically Stimulated Luminescence (OSL) dating of river terraces and alluvial fans across the Dun valley. These new OSL ages of the fan and terrace sediments, in addition to published dates, reveal multiple phases of fan aggradation since > 90 ka until similar to 19 ka and incision during the Holocene with differential uplift, fan truncation, and fluvial reorganization, driven by ongoing tectonic activity. These findings offer valuable insight into the neotectonic development of the Kota Dun valley and contribute to a better understanding of the deformation processes in the mountain front in the Himalaya Central Seismic Gap region.
In the present paper, a comprehensive study of dispersion characteristics of SH-waves in a monoclinic crustal layer lying over a dry-sandy half-space, with special emphasis on the effect of a triangular irregularity at the interface, has been conducted. We have considered both isotropic and monoclinic layer for the analysis of SH-wave propagation with or without sandiness in the half-space. The governing equations representing equation of motion of SH-waves in a monoclinic medium, is formulated to develop dispersion relation. Further, the results are analyzed and discussed for the variation in various physical parameters such as depth of triangular irregularity, sandiness and the directional dependencies in the monoclinic medium. Moreover, a comparative study has been conducted to assess the extent to which these parameters affect SH-wave propagation differently in monoclinic and isotropic layers. These results are illustrated graphically to highlight the importance of considering interfacial irregularity in seismic wave studies.
Recognizing the critical role of groundwater as the primary drinking water source for millions worldwide, particularly in semi-arid regions like Niger, the UN Sustainable Development Goal (UN-SDG) aims to prioritize its sustainable management. Addressing water scarcity challenges through accessible, pure, and naturally filtered groundwater supports UN-SDG objectives for clean water and sanitation (Goal 6), ensuring its availability for domestic, agricultural, and industrial needs. This research contributes to the understanding groundwater potential zones and aquifer protective capacity in Niger's semi-arid region, supporting sustainable water resource management in Niger's semi-arid regions, Tillabery, Niamey, Dosso, Thoua, and Maradi. Using Vertical Electrical Sounding (VES) techniques, 166 data points were collected employing the Schlumberger electrode configuration. Geoelectric properties (resistivity and layer thickness) were derived, and Dar-Zarrouk parameters were calculated. Contoured maps visualizing longitudinal conductance (S), transverse resistance (T), and electrical anisotropy (lambda), helped classify groundwater potential zones. The northeastern part showed low resistance, indicating a good groundwater potential zone. The aquifer is encountered at a depth of 11 m to 15 m in a sandy clay environment. Assessment of longitudinal conductance revealed a moderate to very good aquifer protective capacity, particularly in the southwestern and central-western sectors. To validate, eighteen borehole sites were analyzed, correlating findings with borehole drilling data to create a 3D aquifer thickness model. We found that the aquifer thickness is from 1.5 to 3.5 meters in certain regions exhibiting robust protective capacity, enhancing aquifer resilience against surface contamination. Analysis of the electrical anisotropy coefficient provided insights into geological structures like fractures and bedding planes, influencing fluid flow dynamics and contaminant movement.
Evapotranspiration (ET) is a key water cycle process, linking hydrology and land surface energy balance. This study examines future ET changes using CMIP6 under moderate (SSP2-4.5) and extreme (SSP5-8.5) scenarios for the mid-future (2040-2069) and far-future (2070-2099) relative to the reference period (1985-2014). ET is projected to increase across all the models; however, the magnitude varies across models and regions. Notably, this increase in ET further intensifies in SSP5-8.5 compared to SSP2-4.5. These changes also exhibit seasonal variability, with the monsoon season showing the most significant alterations. Notably, the largest inter-model variability is observed over central India, particularly under the SSP2-4.5 scenario, although some models project localized decreases. Monsoon season has enhanced the ensemble mean of ET variability for the studied CMIP6 models, indicating more precipitation and land-atmosphere interaction. This variability underscores the complexity of climate change impacts, driven by regional differences in climatic responses and model-specific uncertainties.
Groundwater, a vital resource for drinking and irrigation in the semi-arid regions of Andhra Pradesh, is increasingly threatened by rapid depletion and quality deterioration due to growing demands from intensive agriculture and population expansion. In this study, a total of 92 groundwater samples were collected from boreholes during the pre-monsoon (PRM) and post-monsoon (POM) seasons, and their physicochemical properties were systematically analyzed. The major ion sequence in the groundwater was found to be Na+> Ca2+> Mg2+> K+ for cations, and HCO3-> Cl-> SO42-> NO3-> F-for anions. During the PRM season, only 19% of the samples met drinking water standards, with Water Quality Index (WQI) values ranging from 59.18 to 172.21. In the POM season, 22% of the samples were deemed safe for drinking, with WQI values ranging from 70.07 to 229.46. AThe majority of the samples were unsafe due to contamination from human activities, including improper sewage disposal and agricultural runoff. To assess the suitability of groundwater for agricultural and domestic use, Gibbs, USSL, and Wilcox diagrams were utilized. The Gibbs plot indicated that rock dominance governs the groundwater chemistry in the region. Most samples were highly suitable for irrigation, as evidenced by favorable Sodium Adsorption Ratio (SAR), %Na, Soluble Sodium Percentage (SSP), Kelly's Ratio (KR), Residual Sodium Carbonate (RSC), and Permeability Index (PI) values. The Piper diagram revealed a prevalence of Ca2+-HCO(3)(-)and Ca2+-Mg2+-Cl-water types. Using Geographic Information System (GIS) Atechniques, the spatial distribution of groundwater quality was mapped, showing that the majority of samples failed to meet drinking water quality standards, thus necessitating treatment before consumption. Groundwater with elevated concentrations of fluoride and nitrate is unsuitable for drinking purposes and should be avoided. The findings underscore the urgent need for sustainable aquifer management strategies to ensure the continued availability of safe groundwater for both domestic and agricultural use.
The Lansdowne klippe in the Lesser Himalaya is a thrust-plunging syncline comprising Precambrian granite and granite gneiss, prominently exposed around Jaiharikhal-Lansdowne in Garhwal region. The study area consists metasedimentary rocks, quartzose-phyllite, mylonite/phyllonite, granitic and augen gneisses. Granites exhibit medium-coarse, hypidiomorphic, and porphyritic textures with minerals Pl-Kfs-Qtz-Bt-Mus-Tour-Mag-Ap-Zr-Ep. Granite gneisses exhibit a mineral composition similar to that of granite, but with a well-developed foliation plane. Near fault zones, mylonitic textures with quartz ribbons and sericite occurrences, indicate NW-SE shearing. Textural features (porphyritic, perthitic) and geochemical characteristics (alkalic-ferroan, peraluminous), suggest slow cooling from a direct magmatic origin within syn-collisional to post-orogenic settings.
Recent discoveries of kimberlites and lamproites in Proterozoic orogenic belts adjacent to Achean cratons, such as those in South Africa, North-western Australia and George Creek (USA), mark a significant breakthrough in kimberlite exploration. These findings challenge the long-established Clifford's Rule, which traditionally links kimberlite occurrences to Archean cratons. Inspired by this shift, an intriguing question arises, why have kimberlites not been found in the Southern Granulite Terrane of India? This question invites further scientific discussion and exploration.
The study investigates the Bouguer Gravity (BGA) and magnetic anomalies (MA) in the Wajrakarur kimberlite field (WKF), located in Anantapur, Andhra Pradesh, India, an area well known for kimberlite exploration in the South Indian Kimberlite Province. The WKF is characterized by distinct gravity highs and lows between the Closepet Granites (CG) and the adjacently located Cuddapah Basin (CB). Notable gold-mineralized zones are found in the Ramagiri-Penakacherla Greenstone Belt (RPGB) and the Jonnagiri Greenstone Belt (JGB). The study primarily focused on identifying shallow geological features, such as granite, mafic intrusive and fault/shear zones, that occur at a depth of around 3 to 4 km. Additionally, magnetic data indicates the presence of lineaments, oriented along NW-SE, NE-SW, and E-W directions, which align with geological structures, that may imply kimberlite intrusions. The gold mineralization is primarily found in the gravity high zones of RPGB, JGB, apart from a delineated gravity high zone GH3, and along the lineaments. Furthermore, concentrations of Rare Earth Elements (REE) are noted between two gravity highs along the eastern margin of the Closepet granite.
The present study focuses on the integrated analysis of gravity and magnetic data to map subsurface structural features and identify potential mineralized zones within the Proterozoic Cuddapah Basin, situated in the Eastern Dharwar Craton. The study area encompasses the northern segment of the Peninsular Gneissic Complex (PGC) and the northwestern margin of the Cuddapah Basin. It is drained by tributaries of the Krishna River and comprises rock assemblages, PGC, Cuddapah Supergroup, and Kurnool Group. Basic and ultramafic intrusions occur within the both PGC and Cuddapah litho-units. Bouguer gravity and magnetic anomaly maps were interpreted to delineate deep-seated structural frameworks, utilizing contrasts in rock density and magnetic susceptibility. The northern part of the study area features biotite granite, intruded by a prominent NW-SE trending body, well expressed in geophysical data. Structural analysis reveals multiple lineament trends NW-SE, NE-SW, E-W, and N-S, suggesting significant tectonic disturbances that could favour the emplacement of kimberlite and lamproite bodies. Spectral analysis of gravity and magnetic data sets identifies three major depth interfaces, supported by Euler 3D solutions. Two-dimensional gravity-magnetic modeling across the Bollaram and Kollapur clusters, highlights the intrusive bodies and their structural configurations. The study identifies prominent structural trends (NW-SE, NE-SW), subsurface depth interfaces at 0.75 km, 1.46 km, and 3.0 km, and possible potential kimberlite zones, based on gravity-magnetic closures. A comprehensive structural map compiled from geophysical and geological data confirms the presence of previously reported kimberlite and lamproite occurrences, emphasizing the region's mineral exploration potential.
Remote sensing data inferred two major WNW-ESE trending lineaments with a spatial extent of about 3 km parallel to a stream course in Halia watershed located in the Nalgonda district, Telangana state of India. The watershed in semiarid zone is located in granite terrain, covered by red soils with a mean annual rainfall of 636 mm. Integrated study comprising hydrological, hydrogeological, geophysical, drilling, hydrochemical and tracer tests, were carried out during the period 2005 to 2006, to investigate groundwater movement through one of the two inferred lineaments. The observations on rainfall, groundwater level, natural recharge rate, groundwater flow velocity, streaming potential data and fluoride concentration of groundwater indicated that the inferred lineament does exists at deeper depth and in this, preferential flow is the dominant groundwater movement process with the flow velocity of about 14.9 m/d, considering effective porosity of granite/gneiss as 3%.
