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Geography-8

Second Term Notes

Chapter 4

Natural Disasters EXERCISE:

1. Choose the correct word:

a. The scale used to measure the intensity of earthquakes is called Richter scale.

(Winds, cyclones, earthquakes, floods)

b. Sometimes the bursting of dams or leaves also causes floods.

(Landslides, earthquakes, floods, volcanism)

c. The movement of cyclone is anticlockwise in the northern.

(Clockwise, anticlockwise, straight, irregular)

d. The highest intensity earthquake of Chile was recorded 9.5 on Richter scale.

(7.5, 8.5, 9.5, 10)

e. The most disastrous earthquake in the history of Pakistan occurred in 2005

(2005, 2007, 2008, 2009)

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2. Mark T for correct and F for incorrect sentence:

a. The hot molten matter inside the earth is called lava. (T)

b. Earthquake occurred in the ocean is called tsunami. (T)

c. Cyclones are high pressure areas surrounded by low pressure. (F)

d. Landslide is a common and frequent disaster in the plain areas. (F)

e. The earthquake occurred in Pakistan in 2005 measured 7.6 on Richter scale. (T)

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3. Fill in the following blanks:

a. The sudden eruption of lava and gases from the earth crust is called Volcanism.

b. The pipe like outlet through which the lava comes is called Vent or neck.

c. Landslide is one of the frequent natural disasters in mountainous Areas.

d. The point in the earth crust, where earthquakes originate, is called Focus.

e. A low pressure area surrounded by a high pressure area is called Cyclones.

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4. Give short answers to the following questions:

Q1. What is natural disaster?

ANS:

NATURAL DISASTER:

There are a number of natural phenomena which have the potential to cause damage to human

lives and property. For example floods, earthquakes, volcanism, landslides, etc. Any natural event that causes

loss to human lives and property is called natural disaster.

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Q2. Define earthquake.

ANS:

EARTHQUAKE:

The sudden shaking of the earth crust is called earthquake. Earthquake waves originate within the

earth crust and then spread out in all direction. These waves move like the waves formed in a water pool,

when a stone is thrown into it. The earthquake shocks continue for some time and then gradually die out.

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Q3. What is desertification?

ANS:

DESERTIFICATION:

Desertification is the process of the land degradation and gradual conversion of productive land

into less productive or unproductive land. Desertification is one of the most serious environmental and socio-

economic problem in the world today. The major cause of desertification is the removal of natural vegetation

cover.

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Q4. What are the main causes of earthquake?

ANS:

CAUSES OF THE EARTHQUAKE:

Following are considered as the main causes of earthquakes.

a. Movement of Tectonic.

When the tectonic plates break or slide abruptly against one another, they shake the earth causing

earthquakes. Such movements usually occur along the fault lines where plates meet with each other.

The earthquake, which hit the Chitral district of the Pakistan in December 1991, was due to plate

tectonics.

b. Volcanic activity.

The sudden eruption of volcanoes results in the shaking of earth crust causing earthquakes.

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5. Give long answers to the following questions in detail:

Q5. Define volcanism and also describe its impacts. What safety measures are helpful in case

of volcanism?

ANS:

Volcanism:

The sudden eruption of lava and gases from the earth crust is called volcanism. These materials

eject to the surface of the earth through the weaker parts of the earth crust. The pipe like outlet through with

the lava and gases come out is called ‘vent’ or ‘neck’. The lava accumulates around the vent forming a cone.

The hot molten matter inside the earth is called magma. When it comes out to the surface of the earth, it is

called lava. The magma can be thick like tar or thin like custard. It depends on the rock that melted.

Area close to volcanoes are always at risk. The history shows that several times, the volcanoes have damage to

human lives.

The eruption of Mount Vesuvius, Italy in 79 AD buried and destroyed the roman cities, Pompeii and

Herculaneum. About 16,000 people were died due to this eruption.

Impacts of Volcanism:

1. The dangerous gases of lava can cause acid rain.

2. The volcanic dust can block the sunlight affecting the patterns of temperature around the world.

3. The dust can also cause aircrafts to crash.

4. The ash coming out of the volcano can destroy the standing crops.

Safety measures for volcanism:

The following safety measures are helpful in volcanism.

1. Stay away from the place of volcanic eruption.

2. Do not come out of the houses when volcanic ash is falling.

3. Evacuate only when recommended by the authorities in order to be safe from volcanic material.

4. Do not go to low lying areas where there is a risk of ash falling.

5. If you are not evacuating, close windows and doors to prevent ash from coming into the house.

6. Avoid driving, as ash can damage engines and metal parts.

7. Keep a wet cloth on your mouth and nose to prevent the inhalation of dangerous gases.

8. Glasses can protect your eyes from harmful volcanic material.

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Q6. Describe flood disaster in detail.

ANS:

Flood:

When a stream or river gets more water than its channel can hold and the water overflows the banks, this

situation is called flood. The water flows over the banks and onto the flood plain. Floods are the result of

prolonged rainfall and rapid melting of large amount of snow. Sometimes the bursting of dams or leaves also

causes floods.

Impacts of floods:

a. Flood washes out everything coming in its way.

b. It smashes away the buildings, destroys the roads, bridges and other infrastructure.

c. The destruction of communication network leads to the shortage of food item.

d. Flood causes human casualties and livestock deaths.

e. It badly damages the fertile agricultural land and washes out standings crops.

f. It destroys the water supply systems, sewerage lines and irrigation network.

g. The spoilage of water sources results into a shortage of clean water for drinking.

h. Several diseases spreads as a result of water contamination due to floods.

Safety measures for floods

There are some simple things that one can do to safe and protected from floods:

(a). All the family members should know the safe route to the nearest raised, safe site.

(b). In flood prone areas the walls should be made of bricks. Mud walls are more likely to be damage

during floods.

(c). Watch T.V and listen to radio for warning and advice.

(d). Pack warm clothing, essential medication, valuable, personal papers/documents, etc. in water proof

bags, to be taken along.

(e). Inform the local volunteers/officials, regarding the address of the place you are evacuating.

(f). Turn off the main power switch in order to reduce the short circuit risk.

(g). Lock your home and take recommended evacuation routes to safer area.

(h). Do not allow children to play in, or near flood water.

(i). Avoid entering flood water. If you need to do so then take proper protection measures.

(j). Do not eat food, which has been in flood water.

(k). Do not use electrical appliances, which have been in flood water until checked for safety.

(l). Use boiled water for drinking. Do not use the tap water directly.

(m). Be careful of snakes. Snake bites are common during floods.

The floods of July, 2010 were the most disastrous floods in the history of Pakistan. The gushing water in

river Indus and other rivers hit a total of 78 districts. About, 2000 people died and 2946 people got injuries.

A total of 557226 houses were destroyed and over 6 million people were displaced. A huge volume of

standing crops and agriculture lands were also washed along with a number of other severe damages. The

number of people affected by these floods exceeded the combined total of individuals affected by India

Tsunami 2004, Kashmir

Earthquake 2005 and Haiti earthquake 2010.

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Q7. Write a comprehensive note on earthquake.

Ans:

Earthquake:

The sudden shaking of the earth crust is called earthquake. Earthquake waves originate within

the earth crust and then spread out in directions. These waves move like the waves formed in a water pool,

when a stone is thrown into it. The earthquake shocks continue for some time and then gradually die out.

The point in the earth crust where an earthquake originates is called focus. The place on the earth above the

focus is called epicenter. It has been observed that most of the earthquakes originate at a depth of 50 to

100km below the surface of the earth. It has been recorded that eight to ten thousand earthquakes occur

annually in the world. Earthquakes waves travel in all directions from the point of origin. The shocks are

stronger near the epicenter and become weaker away from it.

Measuring Earthquake:

Earthquakes are measured with an instrument known as seismometer, which of record the

shaking waves on a graph. The scale used to measure the intensity of earthquakes is called Richter scale.

The earthquakes occurred in the coast of Chile, south America in 1960 was the highest intensity earthquakes

ever recorded. It measured 9.5 on Richter scale.

Richter scale:

Unit Intensity

1 You wouldn’t notice this

2 30-times more energy than unit-1

3 30-times more energy than unit-2

4 30-times more energy than unit-3

5 windows may break

6 Damages building

7 Major catastrophe

8

9

10 Biggest ever recorded (9.5)

CAUSES OF THE EARTHQUAKE:

Following are considered as the main causes of earthquakes.

a. Plate Tectonics.

When the tectonics plates break or slide abruptly against one another, they shake the earth causing

earthquakes. Such movements usually occur along the fault lines where plates meet with each other.

The earthquake, which hit the Chitral district of the Pakistan in December 1991, was due to plate

tectonics.

b. Volcanic activity.

The sudden eruption of volcanoes results in the shaking of earth crust causing earthquakes.

Impacts of Earthquakes:

a. The shaking of the earth crust result in building collapses, splitting of roads and cracking of bridges.

b. Earthquake may also cause landslides which can block the roads and can burry buildings.

c. It can damage water supply systems, gas pipelines, electric poles and wires, which may cause fires.

d. Earthquakes in the ocean floor can cause giant waves called tsunamis in shallow coastal water. These

waves are very powerful and sometimes smash away entire cities.

Earthquakes in Pakistan:

Pakistan is located in earthquake prone area. The Indian plate is constantly moving

northward and collides with the Eurasian plate resulting into the formation of faults. Movement of plates

along these fault lines causes earthquakes in Pakistan. Most parts of Kashmir Chitral, Quetta, Chaman, Sibbi,

Zhob, Khuzdar and Makran coast are located on fault lines. Besides these regions, Islamabad, Karachi and

Peshawar are also located near the fault lines and are prone to earthquakes.

A major earthquake was occurred in Pakistan was occurred in Pakistan on Saturday October 8, 2005 at

08:50am. The magnitude of this disastrous earthquake was 7.6 on Richter scale. Its epicenter was 65miles

north-east of Islamabad. At least 86,000 people were killed, more than 69,000 were injured, and severe

other damages were also caused in the northern Pakistan. The most severe damages were occurred in the

Muzaffarabad and Balakot.

Safety measures for Earthquakes:

Earthquake gives no warning at all. Sometimes a loud rumbling sound might

signal its arrival a few second ahead. Those few seconds could give you a chance to move to safer places.

Following tips may be followed for keeping safe during an earthquake.

(a). Take cover under a table or other sturdy furniture; kneel, sit or stay close to the floor.

(b). Do not stand in doorways. Shaking can cause doors to fall and cause serious injuries.

(c). If you are in bed, stay there and cover yourself with pillows and blankets.

(d). If you are living in a katcha house, the best thing to do is to move to an open area where there are no

trees, electric or telephone wires.

(e). If your home is badly damaged, then leave it. Collect water, food, medicines, and other important

items before leaving.

(f). Avoid places having loose electrical wires and do not touch metal objects that are in touch with them.

The deadliest Tsunamis in the history of the world occurred

in:

Pacific coast of japan in 2011 which killed 18550 people.

Indian ocean (Indonesia) in 2004 which killed 230,310 people.

Kyusho island, Japan in 1972 which killed 15,030 people.

South china sea, Taiwan in 1782 which killed 40,000 people

(g). Wear shoes to protect your feet from debris.

(h). If the building you live in is in a good condition after the earthquake, stay inside and listen for radio

advice. If you are not certain about the damage to your building, evacuate carefully.

(i). Help injured or trapped persons. Give first aid to the injured if possible.

(j). Help your neighbors. The infants, the elderly and people with disabilities may require special

assistance.

(k). If sewerage lines are damaged, avoid using the toilets. If water pipes are damaged, avoid using water

from tap.

Construction of buildings in Earthquakes prone area:

The people, who live in earthquake prone area, need to take special care in the construction of buildings.

Some of the considerations for building construction in earthquake prone areas are as follow.

i. The whole building should be in the form of a single structure so that it can move as a whole.

ii. There should be enough space between two adjacent buildings so that the collapse of one building

may not destroy the other.

iii. Minimum glass should be used. The decorative glass pieces may be very dangerous when broken.

iv. The foundation of building and frame should be as strong as possible.

v. Lighter building materials should be used in order to reduce the damage in case of collapse.

vi. The use of wood and reusable building material may reduce the cost of rebuilding.

vii. Heavy and bulky items should be kept fastened in the building that they may not fall due to shaking.

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Key words and Terminologies

Disaster: A disaster can be defined as any tragic event which causes damage to life and property, such

as earthquakes, floods, catastrophic accident, fires and explosions etc.

Lava: Lava refers to the molten material erupted from the earth crust as a result of volcanic

activities.

Focus: The point in the earth crust where an earthquake originates is called focus.

Epicenter: The point on the earth surface above the focus is called epic meter.

Fault: The discontinuity between two earth masses, such as the boundary between two plates, is

called fault.

Volcanism: The sudden eruption of lava and gases to the surface of the earth is known as volcanism.

Desertification: The process of land degradation and the conversion of production land to less productive

and unproductive land is called desertification.

Cyclone:

It is a low pressure area surrounded by high pressure.

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(End)

Chapter 6

Natural Regions EXERCISE:

1. Fill in the blanks with suitable words:

a. The climate of topical regions is warm and moist.

b. The north temperate region is located between 23.5°N and Arctic Circle.

c. Cold region is marked with severe cold climate.

d. Rainforests are the ever green forests found in tropical and temperate area.

e. Pakistan, India, and Bangladesh belong to monsoon region.

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2. Encircle the correct option:

a. The climate of temperate region is moderate.

(Hot, cold, moderate, rainy)

b. Deserts’ vegetation is dominated by scrub.

(Trees, scrubs, grasses, crops)

c. The grasslands of South America are called pampas.

(Steppes, prairies, pampas, veld)

d. Downs are the grasslands found in Australia.

(Africa, North America, Australia, South America).

e. The term tundra comes from Russian language which means, treeless.

(Russian, French, German, Indian).

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3. Mark T for correct and F for incorrect sentence:

a. Cold region of the world are mostly situated in polar area. (T)

b. More than 50% of the world‘s plant species are found in monsoon forests. (F)

c. Monsoon region lie between the latitudes 8 to 30 degrees on either side of the topic of cancer. (F)

d. The Mediterranean region is confined to the countries surrounding the Mediterranean Sea. (T)

e. Atacama Desert is the world’s largest desert. (F)

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4. Give answers to the following short questions:

Q1. Define natural region.

Ans: A geographical area, which is uniform in terms of physical characteristics like climate, relief, flora and

fauna, is called a natural region.

Important natural regions:

Following are the important natural regions:-

i. Rainforest.

ii. Monsoon region.

iii. Grasslands.

iv. Tundra region.

v. Desert.

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Q2. What names are given to the grasslands in different continents?

Ans: Grasslands:

Grasslands are vast grassy plains. These grasslands are called prairies in North America, covering

a vast area. In southern hemisphere, comparatively smaller area are covered by these grasslands. They are

called pampas in South America, veld in Africa and Australia.

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Q3. Which countries are located in Mediterranean region?

Ans: Mediterranean region is a narrow zone between 32° to 40° latitudes in the north and south of the

equator. Countries surrounding the Mediterranean Sea such as Greece, Malta, Algeria, Spain and Egypt, etc.

have this type of climatic conditions. These conditions also prevail over California (USA), parts of Western and

South Australia, parts of South Africa and coastal Chile.

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Q4. What are the types of tundra region?

Ans: Tundra type of conditions can be found in three different regions of the world.

(a). Article tundra:

It includes vast areas of northern Russia and Canada. Arctic tundra is frozen for much of the year and it

is not possible for trees to grow. It is covered with marshes, lakes and streams during the warm

months.

(b). Alpine tundra:

It includes the high mountains regions around the world with severe cold climatic conditions.

(c). Antarctic tundra:

It covers the Antarctic continent and on several islands, including South Georgia and the South

Sandwich Islands.

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Q5. Where are the rainforests found?

Ans: Rainforests are the thick evergreen forests found in the tropical and temperate belts in both the

northern and southern hemispheres. The tropical rainforests cover the countries of Congo and Algeria,, etc. in

Africa; Ecuador, brazil and Columbia, etc. in South America; and Thailand, Vietnam and Indonesia in Asia. The

temperate rainforests spread over south-eastern United States, South Africa, southern china and eastern

coasts of Australia and New Zealand.

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5. Give answers to the following long questions:

Q1. Describe the characteristics of rainforest region in detail.

Ans: Rainforests are the thick evergreen forests found in the tropical and temperate belts in both the

northern and southern hemispheres. The tropical rainforests cover the countries of Congo and Algeria etc. in

Africa; Ecuador, brazil and Columbia etc. in South America; and Thailand, Vietnam and Indonesia in Asia. The

temperate rainforests spread over south-eastern United States, South Africa, southern china and eastern

coasts of Australia and New Zealand.

1. Climate:

The rainforest region is characterized by warm and wet climatic conditions. Mean monthly

temperature exceeds 18°C throughout the year. The duration of day light is quite long with 12 hours in the

equatorial region and decreasing in the mid latitudes. High rainfall is received in this region averaging about

600 mm annually. The rainfall is uniformly distributed throughout the year.

2. Vegetation:

The climatic conditions of rainforest region, i.e. warm temperature, high rainfall and long day

light duration are very favorable for the growth of natural vegetation. These conditions make it the most

thickly forest covered region of the world. More than 50% of plant species of the world are found here. These

forests are also called the ‘earth’s lungs’ because they contribute the highest share to the atmospheric

oxygen. These forests also contribute one fourth of the medicinal plants of the world, therefore, also known as

‘jewels of the earth’.

The people who live and depend on the rainforest have their own specific culture. Some of the tribes found

here include the Yanomami, Kayapo tribes of the Amazon, the Hali of Papua New Guinea, and pygmies of

Africa. These cultures have been adapted to the conditions of the rainforests, and have a good understanding

of the ecosystem. They often have knowledge of medicinal herbs and plant, and understand how to cultivate

rainforest land without upsetting the balance of nutrients in the soils.

Rainforest

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Q2. Discus the climate and vegetation of Mediterranean and Monsoon regions.

Ans:

Monsoon Region:

1. Climate:

The climate of this region is much affected by monsoon winds system. The winters are cool and

dry while the summers are hot and wet. Most of the rainfall is received in the summer months, which is

caused by monsoon winds. Annually, 2000 mm rainfall is received in the monsoon regions. The areas on the

tail end of monsoon winds receive 1000 to 2000 mm rainfall annually.

2. Vegetation:

The natural vegetation of this region varies from one area to another depending on the amount

of rainfall received. The forest cover of the areas with less rainfall is dominated by deciduous trees. However,

evergreen forests can be found in the areas, where sufficient rainfall is received. The common plants species

of this region are sandal, teakwood and bamboo.

Mediterranean Region:

1. Climate:

The climate of Mediterranean region is characterized by hot and dry summer; and wet and mild

winter. Summer temperature is around 21°C while in winter it averages about 13°C. Rainfall usually occurs in

winter season, and ranges annually between 250mm to 1000mm. there is very little or no rainfall in summer.

2. Vegetation:

The vegetation of this region is dominated by olive, citrus fruits (oranges and lemons etc.),

grapes, apricots, walnuts and almond etc. wine making is an important industry based on grapes production.

Tourism is another leading industry of Mediterranean region. This region offers favorable environmental

conditions such as climate, biological diversity and natural resources. Since earliest times, different people

from far off areas have chosen this region to live in.

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Q3. Give a detailed account of the desert regions.

Ans: Desert:

These are the regions with scanty rainfall and arid climatic conditions. Deserts can be classified as

hot desert and cold desert, but aridity is common in both the cases.

1: Location:

The major deserts of the world are located in the western coasts of the continents between 15°

and 30° latitudes in both the sides of the equator. Examples include the Sahara Desert of north Africa, the

great Australia Desert, the Arabian Desert and the Atacama Desert of Chile.

Sahara desert is the largest desert of the world covering an area of 3.5 million sq. miles. It covers several

countries including morocco, western Sahara, Algeria, Tunisia, Libya, Egypt, Mauritania, Mali, Niger, chad,

Ethiopia, Eritrea and Somalia.

2: Climate:

Deserts are some of the hottest places on the earth. In the hot deserts, no cold season can be

seen at all. The day temperature in the open sand sometimes reaches to more than 80°C. The reasons for such

a high temperature are; cloudless sky, dry air, intense insolation and rapid evaporation.

The temperature of the cold deserts remains below freezing point in winter and

rises up to 27°C in summer. Precipitation is very scarce both the hot and cold deserts. Mostly the desert

regions of the world receive less than 100mm precipitation annually. The mid- Sahara desert and the Atacama

desert of Chile receive very little or no precipitation.

In the mid-Atacama desert, only 0.5 mm rainfall was recorded in a period of 17 years.

3: Vegetation:

Some forms of vegetation such as scrubs, herbs and weeds can grow in deserts. The arid

conditions and intense heat of the desert do not favor plant growth. The dominant vegetation of both the hot

and cold deserts is the drought resistant scrub or xerophytes. This includes the thorny bushes, long rooted

grasses dwarf acacias. These plants have highly adapted themselves to the arid conditions of the deserts. Most

of the deserts’ scrubs have long and wide spread roots to get water from a larger area. The leaves are usually

needle like to reduce water loss through transpiration. Some plants such as cacti have thick stems to store

water for the drought period. The seeds are covered by thick skin to protect them in the hot sand till

germination.

Desert fauna includes kangaroo rat, coyote, jack rabbit, and many lizards. These animals remain hidden during

daylight hours to control body temperature and limit their moisture needs.

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Key words and Terminologies

Region: It refers to a geographical region with similar physical and biological conditions.

Rainforest: These are dense forests with a high amount of annual rainfall, located in the tropical and

temperate regions.

Desert: A region that receives extremely low amount of precipitation, less than enough to support

growth of most plants, is called desert.

Tropical: It refers to the region located between equator and the tropic of cancer in the northern

hemisphere and tropic of Capricorn in the southern hemisphere.

Temperate: The region between the tropic of cancer and arctic circle in the northern hemisphere and

tropic of Capricorn and Antarctic circle in the southern hemisphere, is called temperate.

Steppe: These are vast grassy plains located in the temperate regions.

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(End)