Test: Class 11 Gepgraphy NCERT Based - 2


30 Questions MCQ Test NCERT based Tests for UPSC CSE | Test: Class 11 Gepgraphy NCERT Based - 2


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QUESTION: 1

Consider the following statement (s) is/are related to natural vegetation.

1. Natural Vegetation follows the climatic variables and grows naturally.

2. Natural vegetation vary according to the climate, soil and altitude.

Which of the following statement(s) is/are correct?

Solution:
  • Natural vegetation means the plants that have not been grown by humans. It doesn’t need help from humans and gets whatever it needs from its natural environment. There is a close relationship between height of land and the character of vegetations.

  • With the change in height, the climate changes and that changes natural vegetation. The growth of vegetation depends on temperature and moisture. It also depends on factors like slope and thickness of soil.

  • It is categorized into three broad categories: Forest, grassland and shrubs. Natural vegetation means the plants that have not been grown by humans. It doesn’t need help from humans and gets whatever it needs from its natural environment. There is a close relationship between height of land and the character of vegetations. With the change in height, the climate changes and that changes natural vegetation.

QUESTION: 2

Which of the following forests are found in the Western Ghats, hills of the north eastern region and the Andaman and Nicobar Islands.

Solution: Tropical Evergreen forests are a dominant part of the Natural vegetation in India.The evergreen forests are essential in not only promoting greenery on the planet, but they are also useful in the continual survival of animals and plants in the forest ecosystem. The trees are evergreen as there is no period of drought. They are mostly tall and hardwood.

QUESTION: 3

Consider the following statement (s) is/are regarding deciduous forest.

1. It is found in regions where rainfall is between 70 and 200 cm.

2. Forests are divided into moist and dry deciduous on the basis of the availability of water.

Which of the following statement(s) is/are correct?

Solution:
  • A deciduous forest is a biome dominated by deciduous trees which lose their leaves seasonally. The Earth has temperate deciduous forests, and tropical and subtropical deciduous forests, also known as dry forests.

  • Another name for these forests is broad-leaf forests because of the wide, flat leaves on the trees. Trees in tropical deciduous forests lose their leaves in the dry season and regrow them in the rainy season. In temperate deciduous forests, trees lose their leaves in the fall and regrow them in the spring.

  • Animals inhabiting deciduous forests include insects, spiders, reptiles and birds. Mice, rabbits, foxes, deer, otters, bears and humans are just some examples of mammals that live in deciduous forests. Tropical and subtropical deciduous forests are also home to mammals such as elephants, monkeys, tigers, and giraffes.

  • Deciduous forests are home to trees such as oak, birch, beech, aspen, elm and maple. Tropical and subtropical forests also have teak trees, palm trees and bamboo. Plants found in these forests include flowers, ferns, mosses and herbs. In addition, tropical and subtropical forests feature flowers such as orchids and numerous vines called lianas. The average temperature of deciduous forests is 50°F and annual rainfall averages 30 to 60 inches.

QUESTION: 4

Consider the following statement (s) is/ are about Tropical Thorn Forests.

1. They occur in the areas which receive rainfall more than 60 cm.

2. These consist of a variety of herbs, thorny grasses and shrubs.

Which of the following statement(s) is/are correct?

Solution:
  • A thorny forest is a dense, scrub-like vegetation characteristic of dry subtropical and warm temperate areas with a seasonal rainfall averaging 250 to 500 mm (9.8 to 19.7 in).

  • This vegetation covers a large part of southwestern North America and southwestern Africa and smaller areas in Africa, South America, and Australia. In South America, thorn forest is sometimes called Caatinga, and consists primarily of small, thorny trees that shed their leaves seasonally.

  • Trees typically do not exceed 10 metres (33 ft) in height, usually averaging between 7 and 8 metres (23 and 26 ft) tall. Thorn forest grades into savanna woodland as the rainfall increases and into desert as the climate becomes dryer.

QUESTION: 5

Which of the following states has got the largest forest in the country?

Solution: In terms of area, Madhya Pradesh has the largest forest cover of 77,414 square km in the country, followed by Arunachal Pradesh with 66,964 square km and Chhattisgarh with 55,547 square km.

QUESTION: 6

Which of the following statements is correct about the Biosphere Reserve?

Solution: Biosphere Reserve is a notified area which covers a larger area of land which may cover multiple National Parks, Sanctuaries and reserves as well. It is an area meant for conservation of biodiversity of a specific area.

QUESTION: 7

Consider the following statements

1. Shedding leaves and appearing as vast grassland in dry seasons is a feature of dry deciduous forest.

2. Tendu trees are commonly found in Dry deciduous forest.

Select the correct answer from the following codes

Solution: As the dry season begins, the trees shed their leaves completely and the forest appears like a vast grassland with naked trees all around. Tendu, palas, amaltas, bel, khair, axlewood, etc. are the common trees of dry deciduous forests.

QUESTION: 8

Which of the following is true regarding natural vegetation of India?

1. Himalayan heights are marked with tropical evergreen vegetation

2. The Andaman Nicobar Islands have tropical rainforests

3. The deltaic regions have tropical deciduous forests and mangroves

Select the correct statements using following codes

Solution: India is a land of great variety of natural vegetation. Himalayan heights are marked with temperate vegetation; the Western Ghats and the Andaman Nicobar Islands have tropical rainforests, the deltaic regions have tropical forests and mangroves; the desert and semi desert areas of Rajasthan are known for cacti, a wide variety of bushes and thorny vegetation.

QUESTION: 9

The Forest Act was enacted in which of the following year?

Solution:
  • First Forest Act was enacted in 1927. This is one of the many surviving colonial legislations. It was enacted to consolidate the law related to forest, the transit of forest produce and the duty leviable on timber and other forest produce.

QUESTION: 10

Which of the following statement (s) is/are correct about Indian forest reserve?

1. Indian mangroves cover about 4975 km2 in the coastal regions.

2. Sunderban is the largest mangrove forest in India and it has been added to the list of biosphere reserves of UNESCO.

Solution:
  • The Mangrove ecosystems are unique & rich in biodiversity and they provide numerous ecological services.

  • Mangrove cover has been separately reported in the ISFR 2019 and the total mangrove cover in the country is 4,975 sq km. An increase of 54 sq Km in mangrove cover has been observed as compared to the previous assessment of 2017. Top three states showing mangrove cover increase are Gujarat (37 sq km) followed by Maharashtra (16 sq km) and Odisha (8 sq km). . The deltas of the Ganges, Mahanadi, Krishna, Godavari, and Kaveri rivers contain mangrove forests.

  • The Sundarbans mangrove forest, one of the largest such forests in the world (140,000 ha), lies on the delta of the Ganges, Brahmaputra and Meghna rivers on the Bay of Bengal. It is adjacent to the border of India’s Sundarbans World Heritage site inscribed in 1987.

  • The site is intersected by a complex network of tidal waterways, mudflats and small islands of salt-tolerant mangrove forests, and presents an excellent example of ongoing ecological processes. The area is known for its wide range of fauna, including 260 bird species, the Bengal tiger and other threatened species such as the estuarine crocodile and the Indian python.

QUESTION: 11

Consider the following statement (s) related to black soil.

1. Black soil is rich in metals such as Iron, Magnesium and Aluminum.

2. Typical characteristics of this black soil are swelling (during wet period) and shrinkage (dry period).

Which of the following statement(s) is correct?

Solution:
  • Black soil in India is rich in metals such as Iron, Magnesium and Aluminium. However it is deficient in Nitrogen, Potassium, Phosphorous and Humus. Black soil is of red colour mainly due to its iron oxide content.

  • This soil shares 15 % of all types of soil in India. These soils are made up of volcanic rocks and lava-flow. It is concentrated over the Deccan Lava Tract which includes parts of Maharashtra, Chhattisgarh, Madhya Pradesh, Gujarat, Andhra Pradesh and Tamil Nadu.

  • Typical characteristics of this black soil are swelling (during wet period) and shrinkage (dry period). While dry, it forms very deep cracks of more than 30-45 cm. In Kovilpatti (Tamil Nadu) areas the cracks may extend to 2 to 3 m with a width of 1 to 6 cm. Field preparations take longer time compared to other soil. Only after secondary tillage, the soil is suited for crop production.

QUESTION: 12

Consider the following statements(s) related to desertification.

1. It is a form of land degradation, for example soil erosion in the humid tropics.

2. It is a form of land degradation in aria, semi-arid and dry sub humid areas resulting from adverse human impact.

Which of the following statement(s) is correct?

Solution:
  • Desertification, also called desertization, the process by which natural or human causes reduce the biological productivity of drylands (arid and semiarid lands). Declines in productivity may be the result of climate change, deforestation, overgrazing, poverty, political instability, unsustainable irrigation practices, or combinations of these factors.

  • The concept does not refer to the physical expansion of existing deserts but rather to the various processes that threaten all dryland ecosystems, including deserts as well as grasslands and scrublands.

  • Slightly less than half of Earth’s ice-free land surface—approximately 52 million square km (about 20 million square miles)—is drylands, and these drylands cover some of the world’s poorest countries. 1. Irrigated croplands, whose soils are often degraded by the accumulation of salts.

2. Rain-fed croplands, which experience unreliable rainfall and wind-driven soil erosion.

3. Grazing lands, which are harmed by overgrazing, soil compaction, and erosion.

4. Dry woodlands, which are plagued by the overconsumption of fuelwood. Solutions To Desertification: The struggle against desertification can occur at several levels. Since regional variations in climate are the main causes of the loss of dryland productivity, it is important to understand the influence of global warming in specific dryland regions. According to some models of climate change, many grasslands in western North America, for example, are predicted to be at greater risk of drought due to projected increases in summer temperatures and changes to existing rainfall patterns. Many authorities argue that since desertification and global warming are so closely related, one of the main solutions to the former may be the implementation of effective economic policies (such as carbon trading) and technical measures (such as carbon sequestration) that reduce the production of greenhouse gases. At local scales, however, desertification is often the result of unsustainable land and soil management. To maintain the biological productivity of the land, soil conservation is often the priority. A number of innovative solutions have been devised that range from relatively simple changes in how people grow crops to labour-intensive landscape engineering projects.

Some of the techniques that may help ameliorate the consequences of desertification in irrigated croplands, rain-fed croplands, grazing lands, and dry woodlands include:

1. Salt traps, which involve the creation of so called void layers of gravel and sand at certain depths in the soil. Salt traps prevent salts from reaching the surface of the soil and also help to inhibit water loss.

2. Irrigation improvements, which can inhibit water loss from evaporation and prevent salt accumulation. This technique involves changes in the design of irrigation systems to prevent water from pooling or evaporating easily from the soil.

3. Cover crops, which prevent soil erosion from wind and water. They can also reduce the local effects of drought. On larger scales, plant cover can help maintain normal rainfall patterns. Cover crops may be perennials or fast-growing annuals.

4. Crop rotation, which involves the alternation of different crops on the same plot of land over different growing seasons. This technique can help maintain the productivity of the soil by replenishing critical nutrients removed during harvesting.

5. Rotational grazing, which is the process of limiting the grazing pressure of livestock in a given area. Livestock are frequently moved to new grazing areas before they cause permanent damage to the plants and soil of any one area.

6.Terracing, which involves the creation of multiple levels of flat ground that appear as long steps cut into hillsides. The technique slows the pace of runoff, which reduces soil erosion and retards overall water loss.

7. Contour bunding (or contour bundling), which involves the placement of lines of stones along the natural rises of a landscape, and contour farming.

These techniques help to capture and hold rainfall before it can become runoff. They also inhibit wind erosion by keeping the soil heavy and moist.

8. Windbreaks, which involve the establishment of lines of fast growing trees planted at right angles to the prevailing surface winds. They are primarily used to slow winddriven soil erosion but may be used to inhibit the encroachment of sand dunes.

9. Dune stabilization, which involves the conservation of the plant community living along the sides of dunes. The upper parts of plants help protect the soil from surface winds, whereas the root network below keeps the soil together.

10. Charcoal conversion improvements, which include the use of steel or mud kilns or high-pressure compacting equipment to press the wood and other plant residues into briquettes. Conversion improvements retain a greater fraction of the heating potential of fuelwood.

QUESTION: 13

Consider the following statements(s) related to soil.

1. It is the earth’s fragile skin that anchors all life on Earth.

2. It is composed of countless species that create a dynamic and complex ecosystem and is among the most precious resources to humans.

Which of the following statement(s) is correct?

Solution: Soil is a natural body comprised of solids (minerals and organic matter), liquid, and gases that occurs on the land surface, occupies space, and is characterized by one or both of the following: horizons, or layers, that are distinguishable from the initial material as a result of additions, losses, transfers, and transformations of energy and matter or the ability to support rooted plants in a natural environment.

QUESTION: 14

Consider the following statements(s) related to Soil retrogression and degradation

1. Retrogression is primarily due to soil erosion and corresponds to a phenomenon where succession reverts the land to its natural physical state.

2. Degradation is an evolution, different from natural evolution, related to the local climate and vegetation.

Which of the following statement(s) is correct?

Solution:
  • Soil retrogression and degradation are two important regressive evolution processes which take place due to loss of equilibrium of a stable soil. Retrogression primarily occurs due to soil erosion.

  • Soil Degradation is an evolution process which is different from natural evolution and is largely related to the local climate and vegetation. It is due to the replacement of primary plant communities (known as climax) by the secondary communities. This replacement in turn modifies the humus composition and amount, which will ultimately affect the formation of the soil. To bear in mind is that degradation is largely associated with human activity.

  • In simple words, soil degradation is any sort of change or disturbance in the soil which is undesirable. The consequences of both the processes are-

1. Impacts the yield bearing capacity of the soil.

2. A deterioration in water quality.

3. Economic loss- this is a major negative externality.

QUESTION: 15

Consider the following statements(s) related to Soil degradation.

1. It is the decline in soil quality caused by its improper use, usually for agricultural, pastural, industrial or urban purposes.

2. It is a serious global environmental problem and may be exacerbated by climate change.

Which of the following statement(s) is correct?

Solution: Soil degradation is the decline in soil condition caused by its improper use or poor management, usually for agricultural, industrial or urban purposes. It is a serious environmental problem. Soils are a fundamental natural resource, and are the basis for all terrestrial life. Avoiding soil degradation is crucial to our wellbeing.

QUESTION: 16

Which of the following is/ are the important agents of soil erosion?

1. Water

2. Wind

3. Human Activities

4. Disasters

Which of the following statement(s) is correct?

Solution:
  • Soil Erosion is a common term that is often confused with soil degradation as a whole, but in fact refers only to absolute soil losses in terms of topsoil and nutrients.

  • This is indeed the most visible effect of soil degradation, but does not cover all of its aspects. Soil erosion is a natural process in mountainous areas, but is often made much worse by poor management practices. Soil erosion i.e., the displacement of the upper fertile layer of soil, is a natural process that occurs at a very slow pace due to -

1. Moving Water (splash erosion, sheet erosion, rill erosion, and gully erosion)

2. Wind (surface creep, saltation and suspension)

3. Glaciers (due to heavy weight/ huge mass)

4. Gravity (causes mass movement)

QUESTION: 17

Consider the following statement(s) related to alluvial soils.

1. The soil covers 40 percent of the total geographical area of India.

2. Alluvial soils are formed due to depositional work done by rivers in plains .valleys, floodplains and deltas

Which of the above statement(s) is/are correct?

Solution: Alluvial soils are formed mainly due to silt deposited by Indo-Gangetic-Brahmaputra Rivers. In coastal regions some alluvial deposits are formed due to wave action. Rocks of the Himalayas form the parent material. Thus the parent material of these soils is of transported origin. They are the largest soil group covering about 15 lakh sq km or about 46 per cent of the total area. They support more than 40% of India's population by providing the most productive agricultural lands.

QUESTION: 18

Which of the following comes under the phenomena of mass movement?

1. Soil creep

2. Weathering

3. Landslide

Which of the statements given above is/are correct?

Solution:
  • Mass movement, also called Mass Wasting, bulk movements of soil and rock debris down slopes in response to the pull of gravity, or the rapid or gradual sinking of the Earth’s ground surface in a predominantly vertical direction.

  • Formerly, the term mass wasting referred to a variety of processes by which large masses of crustal materials are moved by gravity from one place to another. More recently, the term mass movement has been substituted to include mass wasting processes and the sinking of confined areas of the Earth’s ground surface.

  • Mass movements on slopes and sinking mass movements are often aided by water and the significance of both types is the part each plays in the alteration of landforms. The variety of downslope mass movements reflects the diversity of factors that are responsible for their origin.

  • Such factors include: weathering or erosional debris cover on slopes, which is usually liable to mass movement; the character and structure of rocks, such as resistant permeable beds prone to sliding because of underlying impermeable rocks; the removal of the vegetation cover, which increases the slope’s susceptibility to mass movement by reducing its stability; artificial or natural increases in the slope’s steepness, which will usually induce mass movement; earthquake tremors, which affect the slope equilibrium and increase the likelihood of mass movement; and flowing groundwater, which exerts pressure on soil particles and impairs slope stability.

QUESTION: 19

What is the reason for the red colour of the red soil?

Solution: Soil color is produced by the minerals present and by the organic matter content. Yellow or red soil indicates the presence of oxidized ferric iron oxides. Dark brown or black color in soil indicates that the soil has a high organic matter content. Wet soil will appear darker than dry soil. Four main factors influence the colour of a soil

1. Mineral matter derived from the constituents of the parent material.

2. Organic matter.

3. The nature and abundance of iron.

4. Moisture content.

Their colour is mainly due to ferric oxides occurring as thin coatings on the soil particles while the iron oxide occurs as haematite or as hydrous ferric oxide, the colour is red and when it occurs in the hydrate form as limonite the soil gets a yellow colour.

QUESTION: 20

Consider the following statement (s) related to the laterite soil:

1. It is formed due to intense leaching away of siliceous matter.

2. They are fully equipped with organic matter.

Which of the statements given above is/are correct?

Solution:
  • The word laterite has been derived from the Latin word ‘Later’ which means brick. These soils when wet are as soft as butter but become hard and cloddy on drying. Therefore, these are widely cut as bricks for use in house construction. Formation: The lateritic soils are particularly found on high flat erosion surfaces in areas of high(>200cm) and seasonal rainfall. The alternating wet and dry seasons lead to the leaching away of the siliceous matter of the rocks leaving behind the compounds of iron and aluminium. These are zonal soils.

  • Areas: These soils have mainly developed in the higher areas of the Peninsular plateau. The laterite soils are commonly found in Karnataka, Kerala, Tamil Nadu, Madhya Pradesh and the hilly areas of Orissa and Assam. Soil Colour: Reddish brown in colour due to the presence of iron oxide.

QUESTION: 21

Consider the following statements:

1. Natural Hazards are elements of circumstances in the Natural environment that have the potential to cause harm to people or property or both.

2. Natural disasters are relatively sudden and cause large scale, widespread death, loss of property and disturbance to social systems and life over which people have little or no control.

Which of the statements given above is/are correct?

Solution:
  • Natural disasters can be categorized as "acute" or "slow" in their onset. They are predictable because they cluster in geographic areas. Natural hazards are unpreventable and, for the most part, uncontrollable.

  • Even if quick recovery occurs, natural disasters can have long term effects. Natural disasters with acute onsets include events such as earthquake, flood, hurricane or typhoon, tornado, fire, tsunami or storm surge, avalanche, volcanic eruption, extreme cold or blizzard, and heat wave.

  • Natural hazards with a slow or gradual onset include drought, famine, desertification, deforestation, and pest infestation. Natural disasters – such as hurricanes, cyclones, earthquakes, mudslides, floods, wildfires, volcanic eruptions and weather events like extreme droughts and monsoons – are likely increasing in frequency due to climate change.

QUESTION: 22

Tropical Cyclones are intense low pressure areas confined to the area lying between

Solution:
  • Tropical cyclones are violent storms that originate over oceans in tropical areas and move over to the coastal areas bringing about large scale destruction due to violent winds (squalls), very heavy rainfall (torrential rainfall) and storm surge.

  • They are irregular wind movements involving closed circulation of air around a low pressure center. This closed air circulation (whirling motion) is a result of rapid upward movement of hot air which is subjected to Coriolis force. The low pressure at the center is responsible for the wind speeds.

  • The cyclonic wind movements are anti-clockwise in the northern hemisphere and clockwise in the southern hemisphere (This is due to Coriolis force).The cyclones are often characterized by the existence of an anticyclone between two cyclones.

QUESTION: 23

The Indian Tsunami Early Warning Centre (ITEWC) established at Indian National Centre for Ocean Information Sciences is located in:

Solution: The Indian Tsunami Early Warning Centre (ITEWC) established at Indian National Centre for Ocean Information Sciences, (INCOIS - ESSO) Hyderabad, autonomous body under Ministry of Earth Sciences, is being upgraded continuously to provide tsunami advisories for the events occurring in the global oceans, though it has been recognized as one of the best systems in the world.

QUESTION: 24

With reference to flood consider the following statements:

1. The National Flood Management Programme was launched in 1954.

2. Disturbances along the natural drainage channels and colonisation of flood-plains and riverbeds are some of the human activities that play an important role in increasing the intensity, magnitude and gravity of floods.

Which of the statements given above is/are correct?

Solution:
  • Floods are natural occurrences where an area or land that is normally dry abruptly becomes submerged in water.

  • In simple terms, flood can be defined as an overflow of large quantities of water onto a normally dry land.

  • Flooding happens in many ways due to overflow of streams, rivers, lakes or oceans or as a result of excessive rain.

  • Whenever flooding takes place, there is the possibility of loss of life, hardship to people, and extensive damage to property. This is because flooding can carry bridges, cars, houses, and even people.

QUESTION: 25

Which of these is/are flood prevention and mitigation strategy?

1. Construction of flood protection embankments

2. Depopulating the flood plains

3. Afforestation

4. Decongesting river channels

Select the correct option using the codes given below

Solution:
  • With the advancement of technology such as satellite and remote-sensing equipment, flood waves can be tracked as the water level rises. Evacuation is possible with suitable monitoring and warning. A warning is issued by the Central Water Commission (CWC), Irrigation and Flood Control Department and Water Resources Department.

1. Mapping of the Flood Prone Areas: Flood hazard mapping will give the proper indication of water flow during floods. Land use Control It will reduce danger of life and property, when the waters inundate the flood plains and the coastal areas. No major development should be permitted in the areas which are subjected to high flooding.

2. Flood Control: It aims to reduce flood damage. This can be done by decreasing the amount of run-off with the help of reforestation. Flood diversion includes levees, embankments, dams and channel improvement. Dams can store water and can release water at a manageable rate. But the failure of dams in earthquakes and operation of releasing the water can cause floods in the lower areas.

3. Flood Proofing: It reduces the risk of damage. Measures include use of sandbags to keep flood water away, blocking or sealing of doors and windows of houses, etc. Restoration of Original Drainage System Drainage system is generally choked by the construction of roads, canals, railway tracks etc. Floods could be checked if the original form of drainage system is restored.

QUESTION: 26

Consider the following statement (s) is/are related to the strategy to combat earthquake disasters.

1. Establishing earthquake monitoring centres for regular monitoring and fast dissemination of information among the people in the vulnerable areas.

2. Modifying the house types and building designs in the vulnerable areas and discouraging contribution of high rise buildings, large industrial establishments and big urban centres in such areas.

Solution:
  • Earthquake is one of the major natural disasters. Every year it causes a huge loss of life and property all around the world. Proper strategies and awareness about disaster management is the need of the hour.

  • This will protect us from the losses and help to cope up with these hazards. However, in order to reduce the destruction caused by these occurrences the disaster management committee has laid some safety measures.

  • An earthquake is the shaking of the surface of Earth due to the sudden release of energy in the Earth’s crust, as a result, seismic waves (also known as S waves)are created.

  • The seismic activities in an area determine the type and intensity of the earthquake. Earthquakes are caused due to sudden tectonic movements in the earth’s crust. When the tectonic plates slide over one another, there is a cause of orogeny which results in earthquakes and volcanoes.

  • These disturbances cause vibrations which spread in all the directions. As there is a relative motion of these plates, there is stress built up, which breaks by releasing the stored energy known as shock waves.

QUESTION: 27

Consider the following statement (s) is/are related to the characteristics of tsunami waves.

1. Tsunamis are high energy sea waves caused mainly by the deep focus earthquakes of high magnitude.

2. Preparing a vulnerability map of the country and dissemination of vulnerability risk information among the people.

Solution:
  • Tsunamis are giant waves caused by earthquakes or volcanic eruptions under the sea. Out in the depths of the ocean, tsunami waves do not dramatically increase in height. But as the waves travel inland, they build up to higher and higher heights as the depth of the ocean decreases.

  • The speed of tsunami waves depends on ocean depth rather than the distance from the source of the wave. Tsunami waves may travel as fast as jet planes over deep waters, only slowing down when reaching shallow waters. While tsunamis are often referred to as tidal waves, this name is discouraged by oceanographers because tides have little to do with these giant waves.

QUESTION: 28

Consider the following statement (s) is/are related to the remedial steps to reduce the risk of life and properties by landslides.

1. Mapping of landslide prone areas as construction of houses, felling of trees and grazing in landslide prone areas should be prohibited or restricted.

2. Afforestation in the vulnerable areas is an effective way of durable landslides control.

Solution:
  • There are wide varieties of the names given to the denudation process whereby soil or rocks are displaced along the slope by mainly gravitational forces and landslides are one them.

  • Landslides refer to the movement of mass of rock, debris or earth down the slope, when the shear stress exceeds the shear strength of the material. It occurs when the consequence of a complex field of forces (stress is a force per unit area) active on a mass of rock or soil on the slope. It happens due to geological causes, morphological causes, physical causes and human causes.

There are two parameters that determine the landslides are as follows:

1. Increase of shear stress: It happens due to the removal of lateral and underlying support; increase of lateral forces as well as load; transitory stresses like blasting, earthquakes etc.; and geological movement.

2. Decrease of material strength: It happens due to the weathering, pore water pressure and changes in structure. The incidents of landslides are increasing day by day due to the over urbanisation, massive deforestation, construction and development work in landslide prone areas.

QUESTION: 29

Which of the following are immediate hazardous effects of earthquakes?

1. Soil erosion

2. Ground lurching

3. Tsunami

4. Floods from dams

Select the correct answer using following codes:

Solution: The following are the immediate hazardous effects of earthquake: Ground Shaking, Differential ground settlement, Land and mudslides, Soil liquefaction, Ground lurching, Avalanches, Ground displacement, Floods from dam and levee failures, Tsunami.

QUESTION: 30

Consider the following statements

1. The point where energy is released is called epicentre of earth.

2. The point on the surface nearest to focus is called hypocentre.

Select the correct answer using the following codes.

Solution: The point where the energy is released is called the focus of an earthquake, alternatively, it is called the hypocentre. The energy waves travelling in different directions reach the surface. The point on the surface, nearest to the focus, is called epicentre.