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Natural Disasters, , A disaster is a sudde, , ao N event that causes a lot of damage., Naturat disasters, , weather of Sen are caused by extreme conditions of, Strong wind : ~ that take place inside the earth., and chan u ay rainfall, extreme temperature,, eh anges inside the earth can seriously damage, Tonment, life and property and cause sufferings, for 4 long period. Let us tearn about some natural, disasters that can affect our fives in a big way., , , , , , , , , , , , , isturbance in the earth’s surface. Earthquakes may, e mild or massive, resulting in destruction on a, pe scale., , ¢ point under the ground where these vibrations, niginate is called the focus of the earthquake. The, point on the earth’s surface directly above the focus oes 5, called the epicenter of the earthquake. Sometimes, Earthquake, , lhe big earthquake is followed by subsequent tremors or milder earthquakes which are, mown as aftershocks., , , , leasuring Earthquakes, , The intensity of an earthquake is recorded by an instrument called a seismograph., , The Magnitude of an earthquake is measured on Richter scale. The numbers on this scale, hinges from 1 to 10. Earthquakes below 6 are considered moderate and mild and those, , ove 6 are considered severe., , fects of Earthquake, , * Cracks develop on the walls of buildings. These cracks may tead to collapsing of the, buildings., , * Electric wires get snapped resulting in short-circuit and fires.

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. It causes, © The undersea carthquakes can cause disasters like tidal waves es harm ty, and property, \, , Safety Measures During an Earthquake, © Ifyou are inside your house, do not try to run out of the building., ° Get under a bed or table,, , © Never use the elevator during the course of an earthquake. This Is decays,, electricity Supply may be cut off leaving you stuck up in the elevator., , ° Ifyou are outdoors, stay at a place till the earthquake stops. Do not stay neg, wy, buildings, tamp Posts, power poles, etc., , When it rains heavily, all, the water does not seep |, through the soil. Most of fo, the rainwater accumulates | ~, over the tand, causing, water logging. Continuous |, rains for several days result, in overflowing of the rivers, and submerging of nearby, areas. This condition is called flood., , O, , Floods Cyclones, , , , , , In coastal areas, heavy rain is accompanied by very strong winds. This is called cyclon, In India, states like Uttar Pradesh, West Bengal, Orissa, Bihar and Assam are prone t, cyclones and floods., , Effects of floods and cyclones, © Fields get immersed in water and the crops, get destroyed., © Electric lines, communication networks and water supply get affected., , © Belongings of people get washed away. People and animals become homeless,, , ¢ Due to unhygienic conditions, germs spread and there is an outbreak of diseases st, as jaundice, malaria and cholera., , Preventive Measures, , © Trees should be planted in large numbers as they slow down the flow of water., ‘© Dams should be built across rivers to check the flow of water and prevent floods., © When floods occur, the people of the area should go to high places., , SCENCE-5

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uot, , Be" ie is a period of very, , fi p "in tack of rainfatt fie me, st riod of time. Lack of rain wii hig, ural agricultural areas, Wells, , "OP There is shortage of drinking, yy yither and finally dic, Animals, ty occur and spread rapidly, , fects of Drought, , There is acute shortage of food and fodder., , ’ [and becomes barren and soil erosion increases,, aSes,, , dry weather, W replon for a, , Ugh temperatures beg AS, , =e, , jitne, Water, Plants and, , loo suffer, Forest &, , , , : Livestock perish due to shortage of water, and fodder resulting in sh i, ayentve Meesilfen resulting in shortage of milk., , a large numb i, « Plant 5, er of trees to increase rainfall and to reduce the chances of drought., » Rainwater harvesting can be done to store water, This can be used during drought., , muchN, , word ‘volcano’ comes from the name “Vulcan” who is the Roman God of Fire. Deep, de the earth, it is so hot that even rocks melt. This molten rock is called magma. The, 4 collects under the crust in reservoirs called magma chambers. Sometimes when, ¢ pressure in the magma chambers becomes too much, the magma is pushed through, els called vents and comes out with great force onto the surface of the earth through, points or cracks. Such an opening in the earth’s stirface is called a volcano and the, ming out of lava , etc. is called a volcanic eruption., lcanoes can be classified into three types based on their nature. These are :, 1. Active Volcanoes : The volcanoes, that erupt regularly or have erupted |, in the recent past and may erupt je, any time in future are known as, active volcanoes. At present there, are about 500 active volcanoes in, the world and majority of them Active Volcano, are found around the pacific ocean, that is why it is called pacific ring of fire. Mount, , Vesuvius and Mount Fuji are active volcanoes., , 7 SCIENCE'S, re

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2, Dormant Volcanoes The, volcanoes that have not erupted, for a tong time but may erupt tn, future, Sitick, Alaska and Mount!, Vji are dormant voteanoes,, , toe, , Extinct Volcanoes : The volcanoes, that have stopped crupting are, called extinct volcanoes, These are, unlikely to crupt again. Mount, Egneont in New Zealand and ’, Mount Kilimanjaro in Tanzania are me, extinct volcanoes., , Effects of Volcano, , © Poisonous gases and dust released from a volcanic eruption can cause severe Tespiratg, problems., , , , , , , ¢ Volcanic eruptions have been known to knock down entire forests., , ° There is an increase in marine temperature which kills aquatic creatures., , , , , , ‘nami’ means wave. When an earthquake takes place unt, 4 the ocean, it causes giant waves that can travel hundrei, j of kilometers through water before it hits the coast. Ths!, waves are called tidal waves or tsunamis. A tsunami is a sera, of waves which sometimes reach a height of 30.5 metre, These waves cause widespread destruction. A tsunami c, also be caused by a volcanic explosion. |, , Effects of tsunami, , © Huge loss of life and property., , © Huge waves wash away everything in their path., © Acres of land get flooded with water., , Preventive Measures, © Evacuate places near the sea if prior warning is given., © If evacuation is not possible, move up to high areas., , 78 ‘SCIEXCE-5, , e, ., , ee scene:

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aa Strong shaking ina Part of the ©, , A arth’s, The point on the earth's surf surface,, , , , , ACC direct|, , i Y above the, , » The bowl-shaped mouth of 4 volca Ve the source of an earthquake., No,, , , , , » Hot, liquid matter below the earth's surf, surface,, , , , + Hot, melted rock that erupts from, , , , , , 4 volcano,, , DP, , , , , , , , , , , , , , Forces of nature such as tem, , - Perature,, condition of the earth. Pressure and magnetic forces keep changing the, , An earthquake is a sudden, . : Movement or disturbance in the earth's surface., ’ The intensity of an earthquake is re ded ., corded by an instrument called a seismograph., , A drought is a period of very hot Lo ; ‘, cacicule region for 4 long ae weather resulting in lack of rainfall in a, , The volcanoes that hav. . :, ernot erupted for a long time but may erupt In future are called, dormant volcanoes., , A tsunami is @ series of huge waves caused by an underwater disturbance such as an, , earthquake or a volcanic eruption., , , , Sa sails, , , , Multiple Choice Questions (MCQs)., Tick (V) the correct word :, , 1. The molten rocks under the earth’s crust are called :, a, magma uw b. lava @ c. vent B®, , 2. The volcanoes that have stopped erupting are called :, a. active volcanoes @ b. extinct volcanoes ve c. dormant volcanoes &, , 3. Land becomes barren and soil erosion increases during :, , a. Floods () b. Cyctones ©) c. Drought &, , 4, The sudden shaking of a part of the earth is called an :, , et. volcano & c. flood @, , a. earthquake