Preface Landslides have become the fast spreading disaster all over the world. In the Indian subcontinent, the Mighty Himalayan Mountains, owing to the Phenomenon of Post Collision tectonics and the related earth movements and seismicities, has been the arena of massive landslides since time immemorial. Though magnitude, frequency and the aerial extent wise it has been less, the Western Ghats and the Konkan hill ranges and the Eastern Ghats are also witnessing landslides in the country. Due to the massive development of Roads, Bridges, Tunnels and Buildings related to the Hydropower, Tourism and the Pilgrim sectors, these mountains stand prone vulnerably exposed to landslides, which cause greater loss to the man and to his properties. The Geological Survey of India, the agency established during the Britisher’s time for the geological exploration, has been mapping the landslides as a part of their national mapping programme and during which landslide was first mapped in Nainital in 1890A.D. by Oldham. Besides GSI, the agencies like CSIR, Border Roads Organization, BMPTC and other NGO’s too have been studying the landslides for mitigation and protection purposes. Recently the GSI has been nominated as the nodal agency for landslides in India. However, the Department of Science & Technology, Govt. of India, New Delhi, being the nodal agency for the Science & Technology issues in the country, has identified more than two decades ago that the Landslides is one of the major disasters with high degree of damage potential and growing like epidemics, and hence warrant comprehensive studies and accordingly initiated a special programme for Landslides Mapping, Mitigation & Management. Under this programme, the DST has evolved and funded large number of research projects on Hazard Vulnerability Mapping, Site specific Geotechnical Investigations, studies on soil and rock mechanics, instrument based forewarning etc. to various academic and research institutions in the country. In the recent years, especially after the advent of Remote Sensing, GIS, GPS and other geophysical tools the horizon of landslide research by DST has been widened and deepened and the research programmes so funded have brought out packages of newer information on landslides. In this connection, the some of the landslide studies carried out mostly using Geomatics technology in the recent years have been distilled into over 21 scientific articles under 7 sub heads viz; Landslides Overview, Earth System Processes and Landslides, Landslide Hazard Zonation Mapping, LHZ mapping and Geotechnical Investigations, Instruments based Monitoring and Forewarning, Satellite Based Landslide Monitoring, Site Specific Landslide Investigations etc. These articles deal with varied issues like geological & Earth surface processes on landslides in parts of north eastern Himalayas and South India, methods of Landslide Hazard Zonation mapping and optimization of techniques and geosystem variables to be used in Landslide hazard zonation mapping from the parts of western Ghats of south India, LHZ mapping and geotechnical investigations in parts of North eastern states, instruments based landslide monitoring and forewarning from Shimla Himalayas, satellite based monitoring of slide movements from central Himalayas and site specific investigations from different parts of the country. The Senior author gratefully acknowledges NRDMS-DST, for having provided such editorial assignment and V.M. Muthukumar, Vice-Chancellor, Bharathidasan University, Tiruchirappalli, Tamil Nadu for the support. While all the Scientific & Technical teams of the Centre for Remote Sensing, Bharathidasan University, Tiruchirappalli, Tamil Nadu are acknowledged. Shri. S. Dhinesh and A. Vijay, Junior Research Fellows attached to Geospatial Chair Professor (the senior Author) need special appreciations for their untiring assistance in the editorial work. The second and also the first author are grateful to Prof. Ashutosh Sharma, Secretary, Govt. of India, Ministry of Science & Technology, Department of Science & Technology for his leadership and to other officials of the NRDMS-DST for further support. The M/S New India Publishing Agency, New Delhi needs a special appreciation for publishing this book with unique getup and grandeur. The authors also convey their thanks to all the Principal Investigators, to whom fund was given by the DST for the studies, for having provided their project completion reports and in some cases articles.

Abstract The article briefly narrates the initiatives taken by the Department of Science and Technology, Govt. of India, New Delhi in providing solutions to rapidly growing Landslide Disasters in India. Duly considering the importance of the issue, the DST has embarked on a National Landslide Programme more than two decades ago and brought voluminous information on Landslide Vulnerability Mapping, Site Specific Landslide Investigations, Landslide Kinematics, Instrument Based Forewarning etc. by funding large number of research projects to various Academic/Research institutions in the country. In addition, the bilateral collaborative programme launched on Geohazards between India & Norway, resulted in bilateral flow of knowledge and capacity building amongst various tiers of the Academic, Research and the Planning Hierarchy, yielding tangible benefits. Keywords: Landslides in India, DST’s Initiatives. INTRODUCTION Landslides cause extensive damages to roads, bridges, human dwellings, agricultural lands, forests and other establishments year after year resulting in immense losses of life and properties. The entire Himalayan region has been the target of intense development activities for the last few decades. Hence the instabilities along the natural slopes are accentuated by the human activities since the development schemes are often not properly planned and implemented (Valdiya 1980; Thakur 2001). This has become the case in most of the mountains in India. Keeping in view of the stability of the slopes, the need of the hour is to achieve sustainable development of the hilly regions while implementing various developmental schemes. So there has to be a major S&T role to play to minimize the landslide problems. This should include all possible corrective and preventive measures to minimize the losses due to this disaster.

Abstract Landslides have become a recurring phenomenon in most of the mountainous regions of the world. In Indian peninsular, the landslides which were mostly confined to the tectonically active Himalayan Mountains once, have started spreading over to the other mountain belts of the Peninsula. The Tirumala – Tirupati hills, which is drawing millions of pilgrims from all over the world is facing landslides especially along the newly built southern uphill ghat road. The geology of the area, studied using Geomatics tools like Remote Sensing, SRTM based Digital Elevation Models, GPS Survey, etc., showed that Tirumala hills is under the grip of upward tectonic movements as evidenced from the N-S and E-W oriented Pleistocene faults, intensely dissected Plateau top Cuddapah Quartzites, retreating escarpments, exhaustive debris slope, extensive valley fills along the slopes, colluvial fills in lower slopes, palaeo debris flows along the southern and western obsequent slopes of the Tirumala hills etc. All these indicate the inherent landslide vulnerability of the slopes. The E-W trending dykes which are piercing the slopes and protruding as ridges add further landslide vulnerability to such fragile slopes. So, the new ghat road laid along such southern slope is obviously facing landslides. However, the detailed Geomatics based studies show that the dykes, valley fills and steep slopes are particularly more vulnerable to landslides. Though remedial measures have been broadly evolved, abandoning the southern uphill new ghat road and widening the older northern downhill ghat road seems to be the better and long term feasible alternative to prevent Landslides in the area.

Abstract Northeastern part of the Indian subcontinent is seismically an active region, and is further prone to excessive rainfall and frequent landslides, which cause disruption of the road networks during the monsoonic months every year. The region owns a typical morphotectonic setup where many active thrusts and faults have carved out the landforms and physiography of the major part of the region. The creeping phenomenon of the N-S trending prominent strike-slip fault, namely the Churachandpur - Mao Fault (CMF), is one of the triggering factors for the frequent landslides and low magnitude earthquakes. The life line of Manipur, the national high way NH39, traverses along and in close proximity to this fault in Manipur, and hence the life is paralysed in the area during the monsoonic months. From the GPS campaign mode studies on the western and eastern sides of the CMF, it is observed that there is a change in the crustal velocities from 16 - 22 mm/yr in the east to 33 - 42 mm/yr in the west. Micro-deformations are also observed in the form of displacements respectively with the vertical, N-S and E-W components of–0.111 mm/yr (downward), 0.03 mm/yr (northward) and –0.011 mm/yr (westward). The net displacement is 0.126 mm/yr with an azimuth of N 85° and dipping of 13° towards west. Neotectonic movements along the CMF, as per the GPS measurements, suggest an aseismic nature of the fault with dextral component. Fault plane solutions of the earthquakes show northerly directed principal P-axis indicating the extension (T-axis) along east-west. The resultant creeping of micro-deformation towards the western slopes of the terrain is aligned with the principal T-axis. The creeping triggers the micro seismicity as well as the landslides along the CMF.

Abstract The Sonapur landslide located in the south eastern fringe of Shillong Plateau falls in NH44 connecting Shillong with Agartala. The slide is repeatedly active and massive debris flows occur during every monsoonic season since 1999. The studies carried out under the NRDMS funded project shows that the slide falls in the tectonically active E-W Dauki fault system, which not only forms the southern boundary of the Shillong plateau but also the near vertical plane along which the Shillong plateau has been uplifted due to the northerly compressive force and the collision of Indian plate with Eurasian plate. Such post collision tectonic uplift and the southerly tilt of the Shillong plateau in its southern part, monoclinal southerly dipping sediments south of Dauki fault, Sylhet trough, occurrence of NE-SW sinistral (shears) and NW-SE dextral faults in Sonapur area, high seismic activity and rainfall are responsible for the Sonapur Landslide.

Abstract The landslides have become the fast spreading disaster all over the Indian sub-continent. As such landslides were mostly occurring in the Mighty Himalayan Mountains, it was all along attributed to active tectonics. But when it started occurring in most of the mountain belts of India, various geological parameters, the anthropogenic phenomenon and rain fall were inferred to be the main causes for the landslides. Hence when this concept emerged, and again the Remote Sensing and the GIS technologies have phenomenally evolved, different types of variables, again on different resolutions and different methodologies have been adopted to prepare landslide vulnerability maps and this has started yielding varying types of outputs. As the landslide vulnerability zonation mapping (LVZ) is the first step in landslide studies it is essential to evolve a suitable methodology for the same. So the present study was carried out in a test site of around 300 sq.km in between Coonoor and Otacamund, Nilgiri mountains, Western Ghats, South India. In the said study, a set of 12 Earth System Parameters/Variables which could contribute to landslide vulnerability were prepared as GIS raster databases from the data interpreted from satellite MSS data and field geological and geophysical data sets. Similar GIS database was generated on 144 landslides. These landslides were superposed over such 12 Earth system parameters data and landslide vulnerability weightages were assigned to each subvariables of these Earth system parameters. In assigning weightages using such landslide incidence data various methods viz; slope, integrated terrain, information value, weight of evidence, index overlay and BIS methods were used and landslide vulnerability zonation maps were prepared adding all the 12 weightages assigned Earth system variables. In this, all the 12 earth system parameters were having same resolutions. Then the outputs were compared which revealed that the information value method is the best suited method for LVZ mapping followed by weight of evidence method.

Abstract Prediction of the occurrences of Landslides requires a set of complex analyses, involving multitude of factors which are to be studied systematically in order to evaluate the landslide vulnerability. The increasing availability of computer-based tools and data storage capabilities are found to be useful in landslide vulnerability mapping. One such significant tool in landslide studies is Geographic Information System (GIS). In this article some approaches were made to model the land slide hazard for Sirumalai Hills, Dindigul District, Tamil Nadu, India using Geographical Information Systems and the same is presented in this paper.

Abstract Landslides are the most common hazards in hilly regions. Rapid development and the resultant uncontrolled interactions with ecosystems are the major reasons for the landslides, besides the rainfall. So, the assessment of landslides hazard vulnerability is a prerequisite before making any developments related to settlements, hill resorts, hydropower projects and the related network of Ghat roads. The present study deals with the assessment of landslides in two different sites; Site-1 located in the Ghat section of Yercaud hills between 10/4 and 29/6 km stones in the southwestern slopes of Shevroy hills, Salem, and the Site-2 located in the Ghat road between Lower camp and Kumuli in Theni districts, Tamil Nadu. The Theni ghat road in the National Highway-220 is connecting Tamil Nadu with Kerala and is the lifeline for Sabarimala, Tekkadi and Munnar. Besides, a series of pan stacks conveying water from Periyar reservoir in Kerala to the power house located at Lower camp in Tamil Nadu also lie in this stretch of hills. Landslide vulnerability mapping was carried out in an area of 130sq.km in Site-1 and 6.7 sq.km in Site-2 by assigning numerical values to the causative factors of slope instability such as lithology, structure, slope morphometery, relative relief, land use and land cover, and ground water conditions following the BIS code No. 14496 (1998) for preparing landslide hazard zonation maps. The study in Yercaud hills revealed that out of 12 slope facets, facet 1 to 6, 9 and 12 fall under moderate landslide hazard zone whereas facets 7, 8, 10, and 11 fall under high hazard zone. The area falling in facets 3, 4 and 5 of Kumuli ghat section fall under high landslide hazard zone, the slope facets 1, 2, 9 and 10 fall in the moderate hazardous zone and other facets in low hazardous zone.

Abstract Similar to other north eastern states of India, the state of Manipur is also prone to recurring landslides. The National Highway 150 and the state Highway in Ukhrul, Nunghar and Paorei sectors often witness landslides due to geological complexities, rainfall and anthropogenic activities. So a study was conducted to prepare the landslide hazard zonation map for the region using the method developed by Bureau of Indian Standards, which indicates that 67.32 km2 (nearly 56%) fall under high hazard zone. The RMR and SMR studies carried out in five test sites in such high hazard zone show that four sites fall under highly unstable category (class IV) and one under partially unstable category (class III). The kinematic analysis indicates dominant wedge failure. The improper landuse, lack of adequate drainage and toe removal for road widening are the major causative factors for the recurring landslides.

Abstract The softer rock types belonging to Tertiary period, intense deformation and the related more frequent tectonic weak planes, high degree of weathering and extensive road cutting are the inherent systems in provoking Landslides in Noney-Nungba segment of NH-53 in the state of Manipur. So Landslide Hazard Zonation mapping was carried out in this segment using BIS method and also geotechnical investigations were carried out in Awang Khull part-II slide and Raungdai slide and on the basis of type of failure and the morphotectonic conditions mitigation strategies were suggested.

Abstract The state of Nagaland located in the northeastern part of the Indian subcontinent is also prone to landslides similar to the other north eastern states due to the softer lithologies, intense deformation and extensive anthropogenic activities. So in order to understand the landslide vulnerability and to evolve remedial measures, a 12 km stretch of the NH-2 from Kohima town in the south to Zhadima junction in the north was studied. The study comprises the preparation of landslide hazard zonation map using BIS method and detailed studies in six major landslides involving RMR, SMR and Kinematic analysis and also the suitable remedial measures for such landslide phenomenon.

Abstract Due to fragile lithology belonging to Disang and Barail groups of the Cretaceous-Tertiary period, intensive structural deformation related to collision tectonics, extensive weathering and the anthropogenic activities in the form of slope cutting for the development and widening of roads lead to frequent landslides in the state of Manipur, India. In this connection, the road section between Tengnoupal and Sita has been studied to understand the landslides vulnerability and to evolve mitigation strategies. The study involved the Petrochemical analysis to elucidate the weathering potential of the rocks, kinematic analysis to understand the network of joints and the strain, slope stability analysis to prepare Land Hazard Zonation mapping and estimation of factors of safety in selected locations. On the basis of these studies, long & short term remedial measures were suggested to mitigate the landslide hazards.

Abstract Geological conditions in the Tertiary mountainous areas of the western and eastern hill ranges of Manipur often cause landslide movements. These repeatedly occur mostly in old landslide regions during rainy seasons on a large scale, causing considerable economic loss and injuries and deaths of humans. In order to improve such landslide hazard assessment of the region for effective mitigation, Electrical resistivity surveys were conducted using Schlumberger array technique on the very unstable and problematic frontal part of the Kotland landslide, NH-37, Manipur along three profiles. Electrical resistivities aided the characterization and quantification of the subsurface rock units, structure and tectonic conditions of the Landslided area which can contribute for the better planning of mitigation strategies. The results lead to the elucidation of depth of the different litho-units and the geometry of failure surface. The probable failure surface was observed between 10 and 22m depth, characterised by low resistivity (< 150 Ωm) and geometry of the sliding surface was rotational. In addition, a fault was also inferred in the resistivity pseudosection model and hence the area may be highly vulnerable to landslides.

Abstract The present study deals with the slope instability analysis of a vulnerable stretch of 16 km between Pratapgarh road intersection and Mahabaleshwar town, which is a part of the state highway-72, Satara district, Maharashtra, India. The highway remains closed during the monsoon seasons, due to the recurrent instances of cut slope failures. So the present research work was conducted with an aim to study the reasons, extent and mechanism of the cut slope failures along the road sections as well as optimization of tools for the assessment of road cut stability of the area. The 16 km stretch was divided into seven vulnerable sections (M1; near Mahabaleshwar - M7; near Poladpur) based on the geological, geometrical and structural attributes. The slope forming mass primarily consists of laterite, weathered basalt and fresh jointed basalt, which are interbedded with red bole at some sections. Limit equilibrium, finite difference and finite element simulation were performed for seven cut slope sections, using similar geometries and material strength attributes for all the analyzing techniques. The assessment was carried out for both dry and saturated conditions to emulate the monsoons. The factor of safety yielded through the limit equilibrium method was the most conservative of all the tools; while the finite element method gave the least conservative figures in terms of factors of safety, being close to the field observations, the safety factor results of finite difference methods were between the limit equilibrium and finite element methods. The cut slope sections composed of weathered basalts and laterites (M1, M2, M3, M6) were found most vulnerable to failure during rains, while the sections composed of fresh jointed basalts (M4 & M5), though overall stable, are susceptible to planar and wedge failures.

Abstract The Himalayas of Himachal Pradesh is prone to landslides due to inherent geodynamic conditions, rainfall and anthropogeny. Besides multi-variate studies on the landslides of Himachal Pradesh, instrument based early warning system was attempted by taking Jhakri landslides as the test site. Various instruments viz; piezometer, vertical inclinometer, Rain gauge, etc. were installed and the paper discusses about the methodology adopted in the installation of the instruments and the observations made from the instruments. While Piezometer did not reveal much information, the Tiltmeter showed minor movements.

Abstract The landslide is a disaster which causes rampant loss to life, property and ecosystems. With increased awareness and technological development, the number of monitoring stations near hazardous regions have increased. To give warning prior to the occurrence of a landslide, the soil/rock mechanics of the underlying bed needs to be studied and understood. This paper examines the current literature and elucidates some features of state-of- the-art landslide monitoring systems. Keywords: Field based sensors, Wireless sensor network, Landslide monitoring INTRODUCTION Advancements in technology have helped us to understand nature better than before, yet the geotechnical parameters causing landslides could not be quantified accurately. The efforts taken in predicting landslides are clearly moving towards this objective and this can be seen by the number of monitoring stations that have been setup in landslide prone areas around the world. The data that is obtained at each location is important in understanding landslides. Each location is unique in terms of soil properties, groundwater, inclination of the slope and weather conditions and consequently, each deployment is unique. The paper narrates the instrumentation based forewarning systems functioning around the world. The paper discusses these aspects hierarchically viz; Landslide prone areas in India, geotechnical instrumentations and their merits, influence of rainfall on landslides, correlation between rainfall and pore pressure, the relevance of different systems for different scenarios etc.

Abstract Since the landslides have started spreading over to the most of the mountain provinces of all over the world, having developed expertise in Landslide vulnerability mapping, Factor of safety, Rock mechanic studies etc. the scientists and the technocrats have started focusing towards developing landslide early warning systems using instruments. As the instrumentation in such vast areas is not feasible satellite based monitoring of landslide movements is fast emerging. In this connection the paper discusses InSAR interferometry based landslide movements carried out in Nainital and Mansadevi areas, Uttrakhand Himalayas, India. Keywords: SAR interferometry, Monitoring movements, Nainital & Mansadevi Landslides. INTRODUCTION Landslides pose greater threats to the population of India also, especially those living in mountainous regions, the top being the Himalayas. Many villages and vital transport routes are endangered by landslides and losses of lives and important infrastructure now become a routine phenomenon. Therefore, studies on surface displacements and landslide movements have become very important. However, due to the large aerial extent of the landslide prone provinces, this task may not be effectively carried out by ground based methods. In the recent years, the availability of interferometric Synthetic Aperture Radar (InSAR) data from a variety of satellite and airborne remote sensing sensors has emerged, as a potential tool that can yield accurate data on surface displacements. Although, monitoring of such low velocity deformations, as we observe in landslides, is only possible if considerably long time series images are available. InSAR derived displacement measurements are not only feasible but also moderate in their costs compared to many ground-based methods. This paper discusses Small Baseline Subset (SBAS) algorithm used to monitor landslide movements.

Abstract Kaliasaur landslide located 18km from Srinagar on the NH-58 in Uttrakhand Himalayas has been repeatedly sliding for the last over 5 – 6 decades totally paralyzing the transport operations in the region and causing beeline of issues not only for the people living in the hilly state but also the tourists and the pilgrims. The study of Geosystems & geodynamics, large scale micro zonation and geotechnical studies using RMR and SMR techniques show that the slide is located in high hazard zone and follow the pattern of wedge and planar failures with vulnerable zone of factor of safety. The toe erosion by the acutely turning Alaknanda river and the mitigation measures in the form of slope disturbance in the upslope part rather protecting slide, has been responsible for the recurring slides. The study further revealed that excessive rainfall is also a triggering parameter and the crown part is widening. On the basis of the studies, mitigation measures have also been brought out. Keywords: Kaliasaur landslides, Micro LSV zonation, Factors of landslides, Mitigation.

Abstract The Nilgiri Mountains of South India is one of the Landslide prone hill ranges in India. The landslides, in general, are due to the independent, interdependent and the combined effects of natural earth system processes, triggering phenomenon and anthropogenic activities. So the scientists, technocrats and the academicians from all over the world have started studying the landslides using various techniques and advanced tools in mapping the morphology, preparing the vulnerability maps and carve out mitigation strategies. But the discrimination of active slides is a difficult task and also needs continuous monitoring and further a time consuming process too. So, in this context, an attempt has been made to study the signatures of active sliding in one of old slides namely the “LINGASLIDE” in which frequent minor sliding events are often reported. In the study, Total station based large scale topographic survey was carried out in LINGASLIDE and from the same 50 cm topographic contours were generated. From such large scale contours, Digital elevation Model (DEM) was generated and from the DEM, shaded relief map was generated.Uutilizing both the contours and shaded relief maps, small slides were mapped in the LINGASLIDE from the well exhibited subsidiary crowns, toes and the traverse cracks. Resistivity tomography surveys were also carried out along two longitudinal profiles and one traverse profile to identify the subsurface geology, the slip surface and the zones of moisture accumulations, if any. The subsidiary crowns, toes, the conjugate fracture systems and the resistivity tomography showed that the LINGASLIDE is active and the sliding is going on towards easterly because of the easterly compression,resulted from the higher slopes caused by the settlements raised over Lingaslide and the obstruction provided by the retaining walls at the toes in the east. Such compressive forces are clear from the NW-SE and NE-SW fractures seen in Lingaslide and the sliding is clear from the cracks seen and monitored in the buildings constructed over Lingaslide.

Abstract The Rawana landslide, located in Sirmuar district of the Shimla Himalayas, Himachal Pradesh is repeatedly active in the recent years. It is a NE-SW oriented slide with the crown in the southwest and the wider toe in the northeast resting in Giri River. During some of the sliding events emanations of heat and gases were also inferred. In order to understand the landslide phenomenon and the causative factors, and there from to evolve mitigation measures, detailed studies of the slides were under taken. The Landslide hazard zonation mapping carried out in Rawana landslide using LHEF rating based BIS method indicates that it is located in high hazard zone. The detailed studies show the complex geological, structural, morphotectonic and hydrological setting. From the studies it is surmised that the toe erosion by Giri river and the rainfall infiltration in the mid slope region are responsible for the slide. Remedial measures have been accordingly evolved.

Abstract The landslide vulnerability of the state of Mizoram is already high due to lithology, structure, geomorphology and seismotectonics and also the rainfall, like the other states of the northeastern region of India. The extensive mining activities along the highways for the building and road materials appear to cause additional problems of landslides. So two prominent landslides occurring in Keifang and Tlungvel quarries,Mizoram were studied. Besides taking stock of the geosystems, boreholes were drilled in both slides and from the total depth drilled and the modified core recovery, the RQD were worked out for the rocks which indicates that geotechnically the rocks of Keifang quarry are weak when compared to Tlungvel quarry. The geophysical surveys too lead to similar inferences. On the basis of the studies a set of mitigation strategies have been suggested.

Abstract The landslides that swallowed the whole of Malin village, Maharashtra on the early morning hours of 30 July, 2014 is one of the major disasters, next only to Kedarnath episode in the recent years. Consequently, the Department of Science and Technology, New Delhi, constituted an expert committee comprising the authors of the article which made a visit and took the on the spot assessment of the disaster. Their observations show that the area is covered by the Deccan basalts, which are layered with compact and vesicular basalts; fractured and jointed basalts due to tectonics and the cooling of the basalts; and have also undergone extensive geomorphic evolution. Due to such geologic/geomorphic setting, the flow layered basaltic hillock in which Malin is located is naturally benched, which is further being leveled for the agriculture purposes. The deforestation, leveling of the hills, excessive usage of water for irrigation and the lack of drainages outlet in such benched and leveled slopes have assigned high degree of landslide vulnerability to the area. Over this, when torrential rainfall occurred in the last week of July, the landslide was triggered. On the basis such inferences, some mitigation measures have been evolved after the visit.