natural hazards

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INTRODUCTION Man has always faced a fury of nature such as,earthquake, volcanic eruptions,floods, droughts, cyclones etc.These all caused a large scale in loss in life and property. We are helpless in front of these nature’s fury.This is known as natural disaster or natural hazards.

Types of Hazards:

Types of Hazards There are two types of Natural hazards: Geological hazards : The hazards which originates blow the surface of earth are known as Geological hazards.Earthquake, volcanic eruption, land slides and avalanches are some of the geological hazards Weather associated hazards :The phenomena generally associated with the weather or climate are called weather associated hazards. Floods, cyclones, Droughts are some of the weather associated hazards.

Earthquake :

Earthquake An earthquake is the result from the sudden release of stored energy in the Earth's crust that creates seismic waves. Earthquakes are accordingly measured with a seismometer , commonly known as a seismograph . An earthquake's point of initial ground rupture is called its focus or hypocente r. The term epicenter means the point at ground level directly above this.The size or magnitude of an earthquake is recorded by richter scale . Seismograph

Occurrence of Earthquake:

Occurrence of Earthquake Earthquakes may occur naturally or as a result of human activities. Smaller earthquakes can also be caused by volcanic activity, landslides, mine blasts, and nuclear tests. Most naturally occurring earthquakes are related to the tectonic nature of the Earth. Such earthquakes are called tectonic earthquakes.

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Causes of Earthquake It causes in the break down or any severe damage to buildings or other rigid structures. Shaking of ground rupture are the main effects created by earthquakes Earthquakes can cause landslides and avalanches, which may cause damage in hilly and mountainous areas . Following an earthquake,fires canbe generated by break of the electrical power or gas lines Earthquakes may result in disease, lack of basic necessities, loss of life, general property damage

Prediction or preparedness:

Prediction or preparedness There are certain phenomenon like,swelling of rocks foreshock or animal behavior which are considered helpful in predicting the earthquake. Houses and buildings should be constructed according to the prescribed building bye laws which are necessary to save us from earthquakes. Awareness should be created among people. Keep away from windows, mirrors etc. If you are out door move to a open area,away from buildings and electric pole.

Volcanic eruption:

Volcanic eruption A volcano is an opening, or rupture, in the Earth's surface or crust, which allows hot, molten rock, ash and gases to escape from deep below the surface. Volcanic activity involving the extrusion of rock tends to form mountains or features like mountains over a period of time. The first step is that the melting of rock masses blow the earth’s surface produce magma.the second step is the move ment of magma towards earth surface.the magma which reaches the earth surface is called lava.The part of earth suface from which magma reaches the earth’s surface is called as volcano

Occurrence of volcano:

Occurrence of volcano Volcanoes generally occur if tectonic plates pull apart or are coming together. A mid-oceanic ridge, like the Mid-Atlantic Ridge, has examples of volcanoes caused by "divergent tectonic plates" pulling apart; the Pacific Ring of Fire has examples of volcanoes caused by "convergent tectonic plates" coming together. By contrast, Volcanoes can also form where there is stretching of the Earth's crust and where the crust grows thin (called "non-hotspot intraplate volcanism")

Causes of volcanic eruption:

Causes of volcanic eruption Large, explosive volcanic eruptions inject water vapor (H 2 O), carbon dioxide (CO 2 ), sulfur dioxide (SO 2 ), hydrogen chloride (HCl), hydrogen fluoride (HF) and ash (pulverized rock and pumice) into the stratosphere to heights of 10-20 miles above the Earth's surface. IT causes a decline in the average temperature at the Earth's surface. Most of the hydrogen chloride (HCl) and hydrogen fluoride (HF) are dissolved in water droplets in the eruption cloud and quickly fall to the ground as acid rain explosive volcanic eruptions release the greenhouse gas carbon dioxide and thus provide a deep source of carbon for biogeochemical cycles.

Prediction and Preparation:

Prediction and Preparation In all volcano prone region, should be formulated and enforced visa vis selecting the location for the buildings as well as the design of structure. National park should be setup near active volcano, to limit the growth of tows around them. Some earthquake can be experience before the eruption takes place, so take it seriously. If the temperature of a hot spring increases, it also indicates the possibility of a volcanic eruption. Maps can be prepare to show the area likely to be effected in the future.


Landslides A landslide is a geological phenomenon which includes a wide range of ground movement, such as rock falls, deep failure of slopes and shallow debris flows. Although gravity's action on an over-steepened slope is the primary reason for a landslide, there are other contributing factors affecting the original slope stability. The land slaide may move at the speed of 300KM/h

Occurrence of Landslides:

Occurrence of Landslides Land slide commonly take place when a cushion of air gets trapped beneath the moving mass. Due to lack of friction between the moving mass and surface land slide occur. Human activities are also responsible for occurrence of landslides

Causes of Landslides:

Causes of Landslides ocean waves create oversteepened slopes rock and soil slopes are weakened through saturation by snowmelt or heavy rains earthquakes create stresses that make weak slopes fail (see liquefaction, Hope Slide) volcanic eruptions produce loose ash deposits, heavy rain, and debris flows. thunder may trigger failure of weak slopes groundwater pressure acting to destabilise the slope Mining Logging vibrations from machinery

Prediction and Preparedness:

Prediction and Preparedness You can reduce the potential impacts of land movement by taking steps to remove yourself from harm's way. Store the following emergency supplies: Food , Water , First aid kit, Flashlights and batteries, Special medications/eye care products. Listen to the radio or watch television for information and instructions from local officials Water landscape to promote early growth.


AVALANCHES An avalanche is a very large slide of snow or rock down a mountainside, caused when a buildup of snow is released down a slope, and is one of the major dangers faced in the mountains. An avalanche consists of rapidly moving granular material that has exceeded the critical static friction threshold and thereby causes additional material to exceed its threshold as well, in a cascading effect During World War I, approximately 50,000 soldiers died as a result of avalanches during the mountain campaign in the Alps at the Austrian-Italian front

Occurrence of Avalanches:

Occurrence of Avalanches A vibration or movement like the voice of a person or a train can start and avalanche Certain weather conditions like wind and rain A rock or a piece of ice can shake the snow to slide down the mountain Water under the snow could make the Avalanche A section of the snow could fall down or break apart and slide down the mountain

Causes of Avalanches:

Causes of Avalanches Avalanches can cause a great loss of life and property. It leads to soil erosion It lead to a thread for the animals life living in that area. Trees and vegetation suffer due to Avalanches

Prediction and preparedness:

Prediction and preparedness Explosives are used extensively to prevent avalanches Snow fences and light walls can be used to direct the placement of snow. Artificial barriers can be very effective in reducing avalanche damage Trees are helpful in reducing of strength of Avalanches


Cyclone A cyclone is an area of low atmospheric pressure characterized by inward spiraling winds that rotate counter clockwise in the northern hemisphere and clockwise in the southern hemisphere of the Earth the velocity of wind within the cyclone often exceeds to 100KM/h .Some cyclone prone areas of India are West Bengal, Orissa, Andra pradesh, Tamil naidu, Gujarat, Maharastra etc. Cyclone view from Space

Occurrence of Cyclone:

Occurrence of Cyclone Cold-core cyclones (most cyclone varieties) form due to the nearby presence of an upper level trough, which increases divergence aloft over an area that induces upward motion and surface low pressure. Warm-core cyclones (such as tropical cyclones and many mesocyclones) can have their initial start due to a nearby upper trough, but after formation of the initial disturbance, depend upon a storm-relative upper level high to maintain or increase their strength. Cyclone prone areas

Causes of Cyclones:

Causes of Cyclones Cyclone can cause lot of devastation to human lives and there settlements. Strong cyclones which blow in coastal areas lead to many casualties. Cyclones can also uproot trees, telecommunication lines, electricity poles,and hence,disrupt normalcy. It can also lead to loss of property After cyclone

Major cyclone:

Major cyclone 1900 U.S.A 10 000 - 12 000 1906 Cook Island 10 000 1963 Bangladesh 15 000 1964(May) Bangladesh 35 000 1965 1965(June) Bangladesh 15 000 1970 Caribbean coast 1 000 000 1977 Honduras 100 000 1985 South-east India 15 000 - 100 000 1991 Bangladesh 139 000 Year Area of Cyclone Death toll (est.)

Prediction and preparedness :

Prediction and preparedness Create an emergency kit of dry food,water container, emergency lighting and first aid kit. Listen to radio, TV or public loudspeakers system for future information. Don’t go outside, until advised. Know your community cyclone plan and how the cyclone warming system work


Floods A flood is an overflow of an expanse of water that submerges land, a deluge. In the sense of "flowing water", the word is applied to the inflow of the tide, as opposed to the outflow.Some flood prone sreas in India are Bramaputra river basin, Ganga river basin, North west river region, Central india and deccan.etc. Flood

Occurrence of Floods:

Occurrence of Floods Floods usually occur due to the volume of water within a body of water exceeding the total capacity of the body. It can also occur in rivers, when the strength of the river is so high it flows right out of the river channel , usually at corners or meanders. These of course, are not applicable in such instances as sea flooding. Floods happen when soil and vegetation cannot absorb all the water. The water then runs off the land in quantities that cannot be carried in stream channels or kept in natural ponds or man-made reservoirs.

Causes of Flood:

Causes of Flood Structures such as buildings get damaged due to flood water. Landslides can also take place. People and livestock die due to drowning. It can also lead to epidemics and diseases. Contamination of water. Clean drinking water becomes scarce Shortage of food crops can be caused due to loss of entire harvest. Cause of Flood

Prediction and Preparedness :

Prediction and Preparedness Coastal flooding has been addressed in Europe with coastal defences, such as sea walls and beach nourishment. Areas can be protected from flooding by a huge mechanical barrier across the River Thames, which is raised when the water level reaches a certain point. By making Dams. Keep a handy first-aid kit.


Droughts A drought is an extended period of months or years when a region notes a deficiency in its water supply. OR A drought is described along period of time when there is un-normal dry weather. The results of this is animals will die because of no water, plants will not grow, and wells will dry up Drought Area

Occurrence of Drought :

Occurrence of Drought Generally, this occurs when a region receives consistently below average precipitation. Change in land use pattern. Due Decrease in vegetation cover there is desertification of soil. Global warming. Drought Graph of Zimbabwe

Causes of droughts.:

Causes of droughts. Drought can lead to starvation and death. Droughts can cause a lot of damage especially to farmers. Farmers have troubles because if they do not get enough rain all the plants and animals will die. Cause of Drought

Prediction and Preparedness:

Prediction and Preparedness Afforestation through planting trees and plants to increase green cover areas Adopting drought resistant varieties of crop. Promoting rain water harvesting. Promoting water conservation and programmes

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Q. In which area of world the most disastrous cyclone took place? :

Q. In which area of world the most disastrous cyclone took place?

Q. Define: 1. Droughts 2. Cyclone 3. Landslides :

Q. Define: 1. Droughts 2. Cyclone 3. Landslides

Q. Give any two prediction against any disaster. :

Q. Give any two prediction against any disaster.

Q. Give any two causes of Floods.:

Q. Give any two causes of Floods.

Q. How does Earthquake occur?:

Q. How does Earthquake occur?

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THANK YOU Made by:Himanshu Yadav

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