Preface Recurrence of geological hazards such as cyclones, floods, tsunami, earthquake and landslides and resultant life and property loss in the recent past has instilled fear among common public. Although the governmental and other agencies work for the betterment of quality of life and protection of natural environment, lack of clear understanding on natural geological hazards and their nature of impact create confusion leading to mismanagement of relief and rescue operations. In this regard, it is felt that making available a single source of information pertaining to types, causes, consequences and mitigation of geohazards would be an ideal effort to create better awareness among common public, planners and administrators. According to a report by the Government of India, lack of capacity to limit the impact of hazards remains a major burden fordevelopingcountries. An estimated 97% of natural disaster related deaths each year occur in developing countries and, although smaller in absolutefigures, the percentage ofeconomicloss in relation to the Gross National Product(GNP) indeveloping countries far exceeds the ones in developed countries. While onlythe direct financial impactsof a disaster suchasdamage to infrastructure and agricultural produce could be estimated, the hidden costs in terms of loss of personal belongings or jobs, widening trade or government budget deficits, or the increasingpoverty, are even higher. Hazard is described as a cause due to which disasters happen, vulnerabilities of which varyaccording to the typeandintensityin addition to various other reasons such as topography, slope, soil and lithology etc. Vulnerability is definedas “the extent to whicha community, structure, service, or geographic area is likely to be damaged or disrupted by the impact of particular hazard, on account of its nature, construction and proximity to hazardous terrain or a disaster prone area.” Risk is a measure of potential impact in the event of such a calamity. Disaster Preparedness is the level of anticipation and fortification against geohazard. Thus, hazard, disaster, vulnerability, risk and preparedness are the five terms that need to be understood and hence individual chapters in this book deal with specific geohazard, cause, potential impact and mitigation measures for the understanding of general reader. Although many sources could supply such information, presentation of facts pertaining to individual disasters in a simple, yet comprehensive way enhances the potential of this book to create better awareness on geohazards. As explained in many of the chapters of this book, better awareness is the pre-requisite to save lives and property from the impacts of geohazards. Mitigation measures for geohazards are dependent on local conditions and there are plenty of published literatures in this regard. For this reason, each chapter has devoted a section on mitigation measures presenting only the policy initiatives and broad spectrum of activities required for containing adverse impacts. Many chapters point out the directives to be undertaken in India by the planners and administrators besides the common public.

In this chapter, an attempt is made to emphasize the fact that while no country in the World is safe from geohazards, a proper understanding on their causes, ways to mitigate them and surviving techniques would help reduce the life and property loss. Each geohazard has its own characteristic way of potential impact and hence classifying vulnerability of different regions and creating awareness on potential impact is essential. In addition to providing basic information on geohazards, this chapter presents a conceptual model on hazard mitigation, rescue and relief operations. INTRODUCTION Every year, thousands of people are killed by volcanic eruptions, earthquakes, landslides and floods. These natural causes damage human settlements and infrastructures (GOI, 2004) inflicting life and economic loss. As human population increases, habitation on hazardous and or vulnerable land becomes more common and the risks posed by these hazards increase. The need to observe their behavior, understand them better and mitigate their effects become ever more urgent (IGOS, 2003). Decades of research may have contributed towards betterment of our understanding on the processes of geohazard formation but still a long way has to be covered to develop better mitigation procedures.

This chapter reviews the published information on tsunami and attempts to characterize tsunamigenic sediments in terms of their microfossil content. Tsunamisare long-period waves generated by vertical displacements of marine watercolumn due to earthquakes, volcanic explosion and landslides. These waves can exceed heights of 25 meters (in shallow water) and lengths upto 100km with a velocity of more than 1000km/hour. Even at this magnitude, they are undetectable in deeper waters owing to very low wave height which in turn reduces significantly the response time, causing sudden havoc along coasts. They can cause flooding of coastal areas and affect areas thousands of kilometers away from their point of origin. These characteristics of tsunami imprint ensuing sediments with unique assemblage of microfossils. INTRODUCTION Shallow water progressive waves with very large wavelength and long duration caused by the rapid displacement of ocean water are called “tsunami”. Tsunami is a sudden non-meteorologically induced impulse in water regardless of size. Tsunamis are formed by submarine tectonic activity more often due to earthquakes and less frequently due to volcanic eruption, landslides near the coast, meteor impact and nuclear explosions. The velocity of the tsunami varies and depends on many parameters such as bathymetry, height of the originating wave, initial pressure changes in the sea, etc. and can travel at a speed of more than 1000 km/hr. At the place of origin (directly above the epicentre of submarine earthquake or any other causative factor), the wavelength may be upto few tens to several hundred kilometres but the wave height is often less than one metre only. Since the velocity is proportional to the depth of the water column, it gets reduced to few tens of kilometres as the tsunami approaches the coast. However, the wave height increases significantly reaching 100 m in extreme cases. As a result, the tsunami strikes the coast with massive force. The effect is colossal in islands with low relief. The tsunami waves appear as flooding with water rushing inside the land more violently and with great force towards a river course. In several cases, when the tsunami arrives, the water level in the sea may drop significantly and the waters receding several hundred metres come back with great speed drubbing the coastal lands doubly from both the directions. Though an event of short duration in terms of geological history, tsunami deposits, owing to their higher rate of deposition and other salient characteristics, find place in stratigraphic records. This chapter is an attempt to review the characteristics of tsunami and tsunamigenic sediments, to find out the ability of microfossil content of such sediments for characterization and to identify tsunami deposits in stratigraphic records.

A review on historic occurrences of tsunamis in the Indian Ocean and their associated characteristics followed by detailed characterization of genetic causes of recent tsunamiarepresented in this chapter. Althoughsubmarineearthquakes occur very frequently, resultant tsunami and its strength relied on many factors including transformation of energy into the ocean water, area of rupturing of ocean floor, duration of rupturing, accompanying submarine slides, kind of material at focus of earthquakes and type of faulting. The direction of tsunami wave propagation plays the decisive role in deciding sites of impacts. Perfect blend of all these parameters is required to make a submarine earthquake to generate devastating tsunami, which is relatively rare in geological history. This is the reason why although there were as many as 77 tsunamis that occurred in the Indian Ocean region during historic past, the recent one of 26th December 2004 is deadly and rare geological occurrence. However, aftermath effects in terms of volcanic eruptions, coastal high wave activities and change in climatic cycles are recorded since then and require constant scientific vigil. INTRODUCTION Tsunami is defined as a sea wave of local or distant origin that results from large-scale seafloor displacement associated with major earthquake or submarine slide or submarine volcanic explosion. Many a times it is incorrectly described as tidal wave or seismic sea wave, as both of these terms mislead in regard to its mechanism of generation. In Tamil Sangam literature, tsunami is cited as “Azhipperalai”. In South America, it is termed as “Maremoto”. Other names for tsunami include “Flutwellen”, “Vloedgolven” “raz de mare” “Vagues Sismique” and Kai e’e. Prevalence of specific terms for tsunami in many such regions and languages itself stands testimony to the fact that tsunami is known to ancient human populations and that tsunami occurred frequently the historics past.

Detailed information on tectonic evolutionary history of the Bay of Bengal is presented followed by elucidation of these characteristics towards tsunamigenesis in this chapter. The Andaman-Nicobar Island Arc (ANIA) is situated on a 1000 km long plate margin and represents a key region in the developing oceanic crustal area of Bay of Bengal. Frequent earthquakes including the tsunamigenic earthquake of 26th December 2004 off the coast of Sunda take place in this region. The subduction of Indian plate under Myanmar-Thailand plate drives formation of chain of Andaman-Nicobar group of Islands. These oceanic crust formation, subduction and arc formation are all seismigenic and generate shallow focus earthquakes in the Bay of Bengal. It is also observed that the seismicity is decreasing as the bathymetry increases towards SW of the Bay of Bengal. Thus, in long term, the slow accumulation of stress as tectonic plates converge may result in many more earthquakes in this region. After a dormancy of over 100 years, the Barren Island volcano renewed its activity following recent earthquakes. The seismic activity along the Andaman-Nicobar trench is continuing with earthquakes of magnitude varying from 4.8 to 7.2 Richter scale. All these observations suggest resurgent and intense tectonic and volcanic activities due to which allied hazards such as tsunami may take place in future. INTRODUCTION The evolving Earth, depending on its heat flow pattern in the mantle throughout geological time, had passed through stages, which are diagnosed through characteristic geodynamic signatures. This chapter focuses on a very active region in the crust, namely, the Andaman-Nicobar Island Arc (ANIA) to recognize such signatures and decipher relative safety of surrounding regions including east coast of India. As similar active arc systems such as Sunda Arc & Japan Arc generate volcanic, seismic and tsunami hazards, understanding the ANIA would be of help assess safety of surrounding regions. Abundant geoscientific literature exists on the northern part of the Indian plate, which is undergoing compressive stress since collision between the Indian and Eurasian plates about 55-45my. However, the behavior of remaining part of the Indian plate underneath the Indian Ocean is still sparcely studied. Owing to these reasons, this chapter attempts to fill the gap in our understanding as well as to assess the implications of renewed phases of geohazard occurrences including that of catastrophic earthquake and tsunami of 26th December 2004.

Need for systematic mapping and hazard zonation is emphasized in this chapter. Though prevention of natural disaster is not possible, its destruction could be minimized through implementation of effective hazard management system. With this motive, the coastal region between Tangapatnam and Ovari, Tamilnadu State has been classified into various categories of vulnerability based on its response to the 26th December 2004 tsunami. Based on the extent of seawater inundation and coastal geomorphic features, we have assessed the tsunami impact and estimated the behavior of the beaches in case of similar havoc in future. This study had shown that the maximum seawater inundation recorded in the study area is 750m in Colachel and the minimum is 100m in Kadiapatanam, Mandakadu and Vaniakudy areas. Chinnamuttom, Kanyakumari, Manakudy, Pallam and Colachel areas are under high risk. INTRODUCTION On 26th December 2004, tectonic disturbances happened near Sumatra Island with an intensity of 9.3 in the Richter scale wrecked havoc on southwest part of India. In addition to inflicting life and infrastructure loss, the resultant tsunami event had also eroded severely the coastal region and modified topography of beach and shallow coastal regions. It did raise the concern of scientists and emergency planners about the impact of larger earthquake and consequent tsunami should there be any recurrence of such event. Despite becoming aware of tsunami hazard, there has been confusion about areas at risk and areas of safety. This chapter is an attempt to assess the vulnerability of part of Tamilnadu coast based on its geomorphological conditions and the impact of recent tsunami. The hazard maps have been generated and are intended for educational purposes, to improve awareness of tsunami hazards and to encourage responsible emergency planning efforts by illustrating the range of possible tsunami events.

This chapter is an attempt to introduce basic facts about earthquake generation and the role of earthquakes in triggering secondary geohazards. Earthquake, unlike manyother geohazards is yet to be fully understood towards occurrence and magnitude for better mitigation measures. Though unpredictibility of this hazard makes it dangerous, earthquakes seldom kill lives. Instead, poor ability of man-made structures against ground-shaking waves has been the real cause of life loss and damage to property in most of the earthquake incidences. Furthermore, earthquakes generate secondary geohazards such as landslide, failure of dams and reservoirs, etc. Thus, earthquake, as a natural hazard has its own characteristic way of potential impactand hence classifying vulnerability of different regions and creating awareness on potential impact among common public is essential. INTRODUCTION The term “earthquake” denotes “shaking/vibration/trembling/ quivering/shuddering/ wobbling of Earth”. Earthquake is the quickest and most unpredictable natural hazard. It is nothing but a series of suddenly generated elastic waves occurring in the Earth due to internal and/or external causes from shallow (few kilometers) to about 700 kilometers depth. It is a form of motion of wave energy transmitted through the surface layer (crust) of the Earth. One generalization that can be made out of scientific and mainstream media information about earthquakes is that, “earthquakes seldom kill; but the associated phenomena such as landslides, flooding, volcanic eruptions and collapse of natural and man-made structures cause the real damage to lives and property”. This chapter is an attempt to describe the basic elements of earthquakes and few mitigation measures.

This chapter presents a case of Jind region of Haryana State, Northern India which had experienced mild tremors of ~ 3 on Richter scale magnitudes in the recent past with a gap of 1 to 2 years. Rejuvenation of the lineament controlled volcanoseismic process is identified as the probable cause of these tremors. This chapter describes seismotectonic characters, micro and mega seismicity of the area and few mitigation measures. INTRODUCTION The Haryana state consists of Delhi Super Group (DSG), Indo- Gangetic alluvial plain in the form of alluvial fan, sand dune, alluvium of Ambala, Yamuna and Ghagghar rivers and Siwalik Super Group (SSG) in the southern, central and northern parts respectively (Fig.1). The study area Jind is located in the central part of Haryana and comprises 200 – 600 m thick Indo-Gangetic alluvium. The alluvium is of Quaternary Period and composes alternating layers of clay, silt, sand and kankar. The Bhiwani and Tosham areas, located south of Jind, show the occurrence of Neoproterozoic granite and rhyolite of Malani Igneous Suite (MIS). The rocks occur in the form of ring structure/ring dyke on the hillocks amidst the alluvium. The metasediments (mica schist and quartzite) of Delhi Super Group are underling MIS at Tosham (located at 70 km southwest of Jind). As Jind region experiences mild tremors and there is no previous published work pertaining to the geology, tectonics and seismicity of the area the chapter records these aspects for better understanding and mitigation of earthquake hazard.

This chapter introduces the readers about volcanoes and associated features and hazards. Volcanic disasters are like any other geohazards in causing dangerous impacts. However, volcanic explosions are preceded by many surficial expressions that can be detected through satellite imageries, thermal sensors, change in magnetic and gravity anomalies, disappearances of vegetation, sudden appearances of anomalous water vapor, thermal springs and abnormal behavior of animals. Hence, unlike other geohazards, volcanic hazards could be forecast with fairly accurate time limits that may allow evacuation and precautionary safety measures. While avoidance is the best mitigation measure, proper land use planning, provision of scientifically designed damming and diversion methods could save lives and infrastructure from lava flows. Though, atmospheric contamination by volcanic gases, ash cloud and pyroclastic materials could not be thwarted and controlled and thus they could cause havoc. INTRODUCTION The term “Volcano” is derived from the name of Roman mythical God of fire “Vulcan”. A volcano is an opening of different shapes, through which, molten rock and gas get ejected either violently or simply flow over earth’s surface. The molten rock and gaseous materials are drawn from deep inside of crust or mantle of the Earth. Repeated ejection of molten materials through vent, fissures or plate margins forms volcanic mountains on earth’s continental or submarine regions. Volcanism is a threat not only to the lives and infrastructure, but it also drastically alters landscape, impacts atmospheric quality and renders forests, cities and villages and cultivation lands useless. In addition, volcanic eruptions are capable of causing changes in global atmospheric cycles. For example, the eruptions of El Chicho’n in Mexico in 1982, Laki volcano in Iceland and Asama Volcano in Japan in the year 1783 and Krakatau volcano of Japan in the year 1883 have all impacted global climate and atmorpheric dynamics.

Readers are introduced through this chapter to a geohazard (Landslide) that is most frequently publicized in mainstream media. Systematic examination of landslides and associated structural, tectonic, geological, geomorphological, meteorological, hydrogeological characteristics and land use pattern of Nilgiri hill area had indicated that steep slope, dipping of rockstowards slope, presence of clay layering in weathered rock types, events of continuous heavy rains, flooding on the slopes and improper land use practices play a major role in the genesis of landslides. Inaddition, ongoing seismotectonic activities in Southern Granulite Terrain of South India and reactivation of hidden blind shear zones were identified to be causative factors of recent increase of landslide occurrences. INTRODUCTION The downward movement of consolidated and unconsolidated soils and rock en masse from any geomorphic feature due to natural or manmade causes under the influence of gravity is termed as landslide (GSI, 1982). Nevertheless, presence of water, clay material, weak joints, favorable slope and many other characteristics also act as catalysis for this event. Landslides are one of the common geological hazards that affect countless population in India, especially in hilly terrains. Different reasons have been ascribed to different landslides of various terrains. Among them, reactivation of Bhavani shear zone (Prasannakumar and Llyod, 2007), high anthropo-geomorphic intervention (Basu, 2005), local geology, precipitation and slope (Bhattacharjee, 2005), presence of local vertical faults, triangular facets, abrupt deflection of streams and neotectonism

This chapter provides an introduction to cyclogenesis, nature of cyclone disaster and historic events. The mechanism that is in practice in cyclone mitigation, information dissemination and relief and rescue operations are detailed. As the state of Orissa is being battered more frequently by cyclones than any other state of India, special emphasis on cyclone disaster management system of Orissa is also discussed. INTRODUCTION Orissa state with immense natural resources is located between 17027’N and 22034’N latitudes and meridians of 81027’E and 87029’E longitudes. Orissa lies on the eastern coast of India with the waters of the Bay of Bengal swirling along its eastern and southeastern boundaries. It shares its boundaries with West Bengal and Jharkhand on the north, Chattisgarh on the west and Andhra Pradesh on the south. Out of the Indian mainland coastline of 7500 km, it constitutes a coastline of about 480 km. It extends for about 155,707 sq.km accounting about 4.74% of the total area of India. According to the 2001 census, it has 3.57 percent of the total population of India. Administratively, it has 30 districts, 3 Revenue Divisions, 58 Sub- Divisions, 51,061 villages and 127 Urban Centers. Based on physiography, Orissa can be divided into three broad regions - the coastal plains, the middle mountainous region and the plateaus, and rolling up lands. The coastal plains extend from the River Subarnarekha in the north to the River Rushikulya in the south. The coastal zone covers nine districts namely Ganjam, Puri, Jagatsinghpur, Kendrapara, Jajpur, Khurda, Cuttack, Bhadrak and Balasore. It is narrow in the north, widest in the middle, narrowest in the Chilika coast and broad in the south. The coastal belt of Orissa lacks hills excepting few hillocks and mounds in the northern and southern parts. It has extensive low lands adjacent to the sea, sloping gently towards the shoreline of the Bay of Bengal. The coastline consists of the lakes, lagoons, marshes, bays and islands and natural harbors. The lakes in Orissa are natural and artificial. One of the blazing example of the natural lake is the Chilika lake.There is only one bay in Orissa which is the Hukitola bay. Eventually there are only two islands in Orissa - the Short’s Islands and the Wheeler Islands. Among the natural harbor, there is only one of its type in Orissa i.e. Paradeep which holds its recognition as the deepest natural port in the whole of India. The main drainage system of this area is represented by several rivers at their old stages flowing sluggishly towards the sea, which form topographic features like peneplains, natural levees, deltas, etc. (Fig.1). The major rivers flowing in the coastal belts are the Subarnarekha, the Budhabalanga, the Baitarani, the Brahmani, the Mahanadi and the Rushikulya. This region is the combination of several deltas of varied sizes and shapes formed by these rivers. The coastal belt has an area of 40,166 sq. km with a population of 68,79,379, which is 45 percent of the population of 9 coastal districts of Orissa.

Despite widespread occurrence and its potency to inflict heavy causalities and damage to economy, generalizations could not be made to define “drought” – leave alone characterization, development of predictive model and common mitigation measures. Regional variation, be it definition or symptoms or causative factors or consequences and mitigation measures is the hallmark of drought. This chapter is an attempt to present a review on characteristics of drought for the benefit of devising mitigation and reclamation measures. INTRODUCTION “Drought” denotes the meteorological, agricultural, environmental, climatic, social, economic and political consequences of a gap between the water availability and demands for the needs of domestic, irrigational, industrial, commercial and recreational consumption in an area over extended period of time. As these demands vary from region to region and depend on too many parameters such as quantum of rainfall, geological and soil characteristics, land use, population, economic activity, climatic conditions, population and culture, drought conditions of an area may not have characteristics of some other region.

This chapter explains how natural disasters are major catastrophic events, which are often aggravated by human intervention, resulting in adverse conditions affecting both natural resources and human habitats. Though drought is as disastrous as any other geohazard, it differs from other geohazards such that it is a ‘creeping phenomenon’, making its onset and end difficult to determine. Only a continuous monitoring of critical parameters ranging from crop failure to joblessness and shifting population, etc, could indicate drought in an area. In this chapter, we demonstrate a GIS based drought forecasting and monitoring model taking Gubbi Taluk of Karnataka as a case study. The approach includes creation of a spatial database of 17 critical parameters and their integration in GIS environment by developing a suitable rating and ranking scheme for the generation of drought severity map. The results have shown that drought could be monitored with the studied parameters and if suitable remedial measures are implemented, their effectiveness could also be monitored with this GIS model. INTRODUCTION India is a large country in terms of geographical area, exhibiting greater agro-climatic variation. The country is susceptible to several natural disasters, which are a major constraint to developmental activities. 

This chapter portrays flooding as a geohazard that can be managed with ease through simple and effective measures. Flooding is a recurrent geohazard that affects vast lands in India and elsewhere. Unlike many other geohazards, flooding event and probable area to be affected could be predicted with fairly accurate levels and hence, proper safety measures could be taken easily. However, as flash floods could not be predicted and the nature of flooding hazard that it brings in added danger of health hazard, crop damage and cutting off of supply and communication networks, flooding is as serious threat as any other geohazard. Scientifically designed urbanization and flood control measures are suggested for minimizing the potential impacts of flooding. INTRODUCTION Flooding is defined as a temporary submergence of a large area (that normally remains dry) under water by overflowing rivers and reservoirs as a result of heavy rains, high winds, cyclones, storm surges, tsunami, melting of snow or dam burst (Arya et al. 2005). The term “temporary submergence” denotes a time period ranging from few hours to about few months depending on type and location of flooding. Although flooding is a natural phenomenon that plays a major role in replenishing wetlands, recharging groundwater and supports agriculture, extreme demands on natural resources due to population growth, people and their property move closer to water bodies

Many types of geological hazards namely, tsunami, earthquakes, tsunami, floods and drought affect coastal areas like any other place on the Earth. As coastal regions are thickly populated and have abundant urban, industrial and recreational establishments, impacts of geohazards are always severe along coastal regions. Compliance to coastal zone regulations, with protection of sanddunesandmangroveswillbe the best mechanism to minimizethe damages from such hazards. In future, climate change may result in more hazards such as erratic rainfall and increase the frequency of droughts, floods and storm surges, etc. In this context, proposed coastal management zone for the coastal protection, disaster mitigation and management tools in coastal areas are examined in this chapter. It is suggested that extensive use of GIS and development of Geodatabase for the risk prone areas will serve as efficient tool for planners and policy makers to deal with geological hazards. In addition, it is felt that more efforts are needed in legal and institutional framework for integrated disaster management planning on local as well as national level. INTRODUCTION Geologic hazards are natural geological processes that inflict severe damage in areas of their operation if the area is utilized by anthropogenic activity in terms of habitation, industrial, recreational or commercial establishments. Many a times, natural geological processes that operated uninhibited for millions of years turn into geological hazards due to human intervention. These losses – lives and economic are not evenly distributed and are more prevalent in the developing countries due to higher population concentration and low level of economic growth. United Nations had realized the need of reducing these losses due to natural disasters and declared the last decade (1991-2000) as the International Decade for Natural Disaster Reduction. Objective of this proclamation was to reduce, through concerted efforts, the loss of life, property damage and socio-economic disruption caused by the natural disasters particularly in the developing countries (Tewar, 2000).

This chapter documents shoreline changes of the Dakshina Kannada and Udupi districts of Karnataka State for the period between 1967 and 2005 studied by comparing the SOI topographic maps with IRS-1C/1D LISS-III satellite imageries through GIS techniques. Examination of coastal geomorphology, sediment flux and effectiveness of seawalls had indicated that the 130km long coastline of Dakshina Kannada and Udupi districts is essentially stable, but for seasonal variations. It has been estimated that, out of 130km, about 55km long coast is vulnerable to sea erosion, of which, 25km is covered byseawalls and covering another 10km length underway. It is revealed through field examination that protection of coastline through these measures is satisfactory only along few patches while other stretches of seawalls simply shift the zone of erosion to adjacent coastline owing to many reasons including quality of construction, unscientific positioning of seawalls, etc. It is also inferred that same is the case of many other coastlines elsewhere including Kerala coast. These experiences warrant scientific design and implementation of coastline protection measures. INTRODUCTION The 130km long coastal zone of Dakshina Kannada and Udupi districts is one of the densely populated coastal zones of India. The coastline is almost straight, regular and oriented towards N22°W, N12°W and N6°W directions at south of Mangalore, north of Mangalore and north of Malpe respectively. Barrier beaches and spits, ancient beach ridges, marshes, swamps and tidal flats characterize this zone. Natural features and man-made structures interrupt the shoreline. The natural features include estuarine mouths of Netravati-Gurpur rivers near Mangalore, Mulki-Pavanje rivers near Mulki, Udyavara river near Malpe, Sita-Swarna rivers near Barkur, Kollur-Chakra-Haladi rivers near Kundapur and rock exposures near Someshwar, Surathkal, Mulur, Kapu and north of Malpe (Fig. 1). The man-made structures include one major and four minor ports; breakwaters at the Netravati-Gurpur estuary, New Mangalore Port and Malpe harbor and a number of seawalls placed at various places along the coastline (Fig. 2). All these structures/features bring about local irregularity and contribute to erosion and accretion along the shoreline to some extent. Apart from these, source of beach material, coastal processes like wave refraction, longshore current, littoral drift etc.

This chapter sheds light on a geohazard namely quicksand. Unlike other geohazards, it waits for its victims to cause hazard. Though discounted as a myth and also as a monster problem in Hollywood film stories, phenomenon of quicksand is real and could inflict life threatening dangers. Analyses of genetic causes, associated properties and locales of its occurrences indicate that more deaths might have resulted due to panic and drowning in waters than by quicksand itself. Based on these inferences, potential mitigation measures are presented in this chapter. INTRODUCTION Quicksand, referred as “pudhai manal” in Tamil, is one of the lesser known dangerous natural phenomena that cause death of human and other unsuspecting animals. It is a geohazard of different sort. It is different in a sense that it never “goes” anywhere like tsunami or causes hazard like flood or landslide or any other geohazard; but it waits for hapless victims; that is., it is harmless until human beings or other fauna step into the region of quicksand. It is commonly prevalent in many river beds and other locales near water bodies located amidst dense forests. Many a deaths occur due to quicksand but go unnoticed owing to its “non catastrophic” nature. It is also a geohazard less understood pertaining to causes of formation, potential to cause damage and occurrence (www.mythbuster.com). This chapter is an attempt to review the existing literature on this geohazard for better understanding.

impacts other speheres and that too on a distal place! This chapter explains how global warming affects remote places like highlands of Bhutan. Severe hot summers during the year 1994 led to excessive melting of glaciers in the higher Himalayas. The exceptional melting contributed enormous amount of melt water to the lake basins, which caused breach of the morainic dam and consequent enlargement of the outlet of the Luggye Tsho and the Tshopda Tsho, Bhutan. Floods followed the breach on October 7, 1994. These floods destabilized the slopes on either bank of the Pho Chhu near Tshopda Tsho outlet making them prone to landslides. The flash floods also eroded the left lateral moraine of the Raphstreng Tsho, which had disturbed the original angle of repose. The Raphstrcng area is also prone to ice avalanches, rock glaciers, surge of which can damage the rim and also cause spillover of water. Examination of geological, geomorphological, geotechnical, microclimatic and hydrographic information in and around the glacial lakes led to improved understanding of breach characteristics based on which mitigation measures were suggested and implemented in the years 1996-97. Since then the lakes have remained intact. From this case study and satisfactory performanceof mitigationmeasures suggest that similar integrated studies have to be conducted for thorough understanding of hazard prone areas based on which mitigation measures have to be implemented for successful reduction of impacts. INTRODUCTION The Lunana area, situated in the northern district of Gasa, is one of the most extensively glaciated terrains of Bhutan (Fig. 1). In response to the general global warming, these glaciers like those of other parts of the Himalaya are in a state of steady retreat, often leaving behind a chain of lakes. Though the glacial lakes endow scenic beauty, they also pose environmental hazards, due to frequent bursting of their morainic dams and consequent flash floods. The last lake-burst occurred on 7th October 1994, leading to floods in the Pho Chhu River. Following floods, the Geological Survey of India in collaboration with the Royal Government of Bhutan, investigated the Lunana area to identify the causes and effects of the floods and suggest remedial measures. More than a decade had passed since the implementation of mitigation measures and there has been no such breach and flood despite continued Glacial Vetreat during to Global Warming. This chapter describes the characteristics of these glacial lakes, nature and results of the study and mitigation efforts.

reach out their fingers it is gone” - Chinese Philosopher Lao Tzu Tao Te Ching. True to his verses, geohazards are phenomena regulated by the law of natureand it is beyond the human intellect to understand thoroughly and capability to conquer. This is the lesson learnt by us from so many incidences that geohazards cause greatest havoc wherein natural processes are going on and are inhabited by humans. Greed for natural resources and population pressures on the earth’s resources are the causes of many a catastrophic event. Examples in this regard are galore including, damning river courses and location of urban centers along rivers and coasts – flooding, cyclonic storms, tsunami hazards; alteration and deforestation hill slopes for agricultural and construction activities – landslides; unscrupulous utilization of ground water resources – drought, etc. This chapter is an attempt to draw the attention of human communityasa whole toturn towards learning to live with the nature without alterning the natural processes to get rid of impacts of geohazards as a best ever mitigation measure. In other words, this chapter attempts to emphasize the need to change our attitude to escape from natural hazards instead of attempting to tinker around natural processes only to get battered at the end. INTRODUCTION Oxford English dictionary states that the word ‘disaster’ is derived from the 16th century French word ‘disastre’, which is a combination of two terms namely, ‘Des’ meaning bad or evil and ‘astre’ means star. Thus “desastre” signifies a ‘bad star’ or ‘evil star’. Disaster, therefore, implies loss or damage occurring due to some unfavorable star. However, in terms of modern knowledge, the word ‘disaster’ denotes any odd event, whether natural or man made, which can bring about sudden and great miseries to humanity in the form of loss of life or/ and property.

Glossary on Geohazards In this section, we have presented a list of terms related to geohazards and attempted to provide explanation to them. These terms are collected from various sources not limited to but inclusive of those listed in references. While we thank the sources for their permission to utilize this valuable information, we undertake that the correctness of the terminologies and their meaning is the sole responsibility of the authors alone and not necessarily that of sources. Accelerograph : Name of an instrument that records the vibrations of earth surface. Accretionary wedge : Pile of sediments accumulated in subduction zones located between collisional margin of oceanic and continental plates. Acid rain : Meteoric precipitation with dissolved components drawn from atmospheric pollutants. By dissolving gaseous materials present in atmosphere supplied by automobile, domestic, industrial and other sources, the rainwater becomes weak carbonic acid, nitric acid and sulphuric acid and affects the natural environments. Active volcano : A volcano, which is currently erupting or has erupted in recorded history. Active fault : Faults are considered to be active if they have moved during historic times or showing recent evidences of movement along fault plane and or generating seismicity. Active Beach : Dynamic portion of beach that shows changes in terms of profile, morphology and sediment quantity and texture. Changes may be at the scale of daily, diurnal, seasonal or annual. Waves, tides and currents may effect changes. Aftershock : Earthquakes that follow the largest shock of seismic activity. They are smaller than the “mainshock” in terms of magnitude and intensity. Minor seismic vibrations that precede major shock are termed “foreshock”. Agglomerate : Consolidated pyroclastic deposit composed of volcanic fragments and bombs. Aggradation : It is the process of accumulation of sediment to cause surface elevation and or morphological change of depositional topography/landscape. Alluvium : Sediment deposits accumulated during since ice age principally under the influence of rivers along channel course during normal flow and all over flood plain during flooding events. Although sediment size varies as a function of sediment load, carrying capacity and energy conditions, a general decrease is discernible from channel bank to regions far away. Amplification : Response of earth materials depending on their density to the impending seismic waves. It is dependent on intensity and duration of shaking, topography of the region, geometry and velocity structure of rock types, etc.