How Many Earthquakes 2019

You will learn many basic concepts related to the earth in this article. You have to study many factors of human activities closely associated with your daily life. In Geography we also study the financial, social, cultural interactions between various human communities.

   Earthquakes 

         An earthquake is the most unpredictable of natural calamities. When it occurs it lasts for a few seconds. But it has devastating effects. An earthquake can cause the deaths of thousands of people and injure even more. Near and dear ones are Killed, lost or handicapped. After an earthquake, there is no food or drinking water for days. victims suffer from health problems and thousands are rendered homeless. Rescue Operations are undertaken almost immediately. The various government departments and local organizations swing into action. The armed forces are also called out to help. They try to save people trapped under fallen buildings. The local public do their best to save people. Organizations such as the Red Cross come to help. Students and people from all parts of the country collect funds for the affected people. But more needs to be done. The people who are affected by earthquakes need to be given hope and courage. They have to be given confidence to face the future ahead. In the interior of earth, there is tremendous amount of energy. This energy results in seismic waves. It causes movements of the earth's surface in the form of tremors, shaking and cracking. The vibrations caused due to all these movements results in an earthquake.

•  Earthquakes 
• Effects of earthquake
• Floods 
• Storms 

Earthquake : 1) Large scale damage to life and property. 2) Buildings collapse due to tremors and vibrations of the earth's crust. 3) Directions of the flow of rivers can be changed. 4) Destruction of infrastructure such as buildings, bridges, roads and railway tracks.

• Vibrations and cracking up of the earth's crust is knows as earthquake.
• Interior of the earth has tremendous energy. There are some movements in these layers. 
• This causes seismic waves which in turn cause movements of the earth's surface. 
• It results in tremors, shaking and cracking up of earth's surface resulting in an earthquake.
• Besides natural causes, man-made causes such as construction of large dams can also lead to an earthquake.

Effects of earthquake :

• Destruction of the infrastructure such as buildings bridges, roads, railway tracks, etc.
• Changes in the direction of the flow of rivers.
• Excessive loss of life and property.

• Destruction of the infrastructure such as buildings bridges, roads, railway tracks, etc. Infrastructure is the set of fundamental facilities an systems that support the sustainable functionality of households and firms. Serving a country, city, or other area, including the services and facilities necessary for its economy to function. Infrastructure is composed of public and private physical structures such as roads, railways , bridges , tunnels, water supply, sewers, electrical grids, and telecommunication (including Internet connectivity and broadband access.) In general, infrastructure has been defined as "the physical components of interrelated system. Especially in light of the massive societal transformations needed to mitigate and adapt to climate change, contemporary infrastructure conversations frequently focus on sustainable development and green infrastructure. San Francisco Ferry Building at  night One way by which to classify types of infrastructure is to view them  as two distinct kinds : hard infrastructure and soft infrastructure. Hard infrastructure refers to the physical networks necessary for the functioning of a modern industry. This includes roads, bridges railways, etc. Soft infrastructure refers to all the institutions that maintain the economic, health, social environmental, and cultural standards of a country.

• Changes in the direction of the flow of rivers. Rivers changing direction is relatively common, but is usually caused by tectonic forces, landslides or erosion......

• Excessive loss of life and property. Earthquake causes heavy loss of life and property. At the Earth's surface, earthquakes manifest themselves by shaking and displacing or disrupting the ground. When the epicenter of a large earthquake is located offshore, the seabed may be displaced sufficiently to cause a tsunami. Earthquakes can also trigger landslides and, occasionally, volcanic activity

Floods : Human changes to the environment often increase the intensity and frequency of flooding for example land use change such as deforestation and removal of wetlands changes in waterway course or flood controls such as with levees, and larger environmental issues such as climate change and sea level rise. In particular climate change's increased rainfall and extreme weather events increases the severity of other causes for flooding resulting in more intense floods and increased flood risk. Flooding may occur as an overflow of water from water bodies, such as a river, lake, or ocean, in which  the water overtops or breaks levees,  resulting in some of that water escaping its usual boundaries. While riverine flood damage can be eliminated by moving away from rivers and other bodies of water, people have traditionally lived and worked by rivers because the land is usually flat and fertile and because rivers provide easy travel and access to commerce and industry. Flooding can lead to secondary consequences in addition to damage to property.... 

1) Huge loss to life and property. 2) Erosion of soil 3) Standing crops are destroyed. 4) Epidemics of infectious diseases may spread after the floods recede, causing health problems to the people. When there is excessive rains in the same place in a short span of time, then a river may overflow its banks. In cities, water drainage system falls short. The gutters or drainage lines are choked. This results in overflow of water on the roads and surrounding areas. It may also enter the houses. Floods are caused in this way.

1) Huge loss to life and property. 2) Erosion of soil 3)Standing crops are destroyed.

• During floods, water is accumulated at one place in a very large amount.
• Excessive rains cause floods.
• River overflows its banks and this results in flood.
• The water drainage system in be cities may fall short resulting in choking of  gutters and drainage lines. This results in flooding if there is an excessive rainfall.
• In such case, water verily flows on the roads and enters the house even causing destruction.

Effects of floods :

• Huge loss to life and property
• Erosion of soil.
• Standing crops are destroyed
• The epidemic of diseases spread and affect health of the people.

Storms :

1) The low-lying areas and the coastal areas face lots of destruction. 2) Life and property is damaged. 3) Electric supply gets disrupted. Transport and communication is affected. 4) Trees and crops are uprooted. 5) People are stranded at one place.

       The formation of high and low pressure belts in the atmosphere results in changes in the weather. These pressure belts cause strong winds resulting in storms.

• There is formation of high and low air pressure belts in the atmosphere.
• This causes changes in weather.
• Strong winds are formed due to this, resulting in storms.

Effects of storms :

• Storm affected regions undergo great damages.
• There is tremendous loss of life and property.
• The electric supply is disrupted.
• Transport and communication is disrupted.

• Storm affected regions undergo great damages :  A storm is any disturbed state of an environment or in an astronomical body's atmosphere especially affecting its surface.  And strongly implying severe weather. It may be marked by significant disruptions to normal conditions such as strong wind, tornadoes, hail, thunder and lightning (a thunderstorm), heavy precipitation (snowstorm rainstorm), heavy freezing rain (ice storm), strong winds (tropical cyclone, windstorm), or wind transporting some substance through the atmosphere as in a dust storm, blizzard sandstorm, etc.

       Storms have the potential to harm lives and property via storm surge, heavy rain or snow causing flooding or road impassibility, lightning, wildfires, and vertical and horizontal wind shear. Systems with significant rainfall and duration help alleviate drought in places they move through. Heavy snowfall can allow special recreational activities to take place which would not be possible otherwise, such as skiing and snowmobiling.

• There is tremendous loss of life and property:  Earthquake happens due to tectonic movements in the earth crust. Some immediate effect of earthquake are ground shaking, ground rupture, landslide and tsunamis.

• The electric supply is disrupted : A power outage (also called a power cut, a power out a power blackout, a power failure, a power loss, or a blackout ) is the loss of the electrical power network supply to an end user.  There are many causes of power failures in an electricity network. Examples of these causes include faults at power station damage to electric transmission lines.....

• Transport and communication is disrupted: Transportation and communication lifelines are among the critical networks required for moving material, people and information among locations distributed in geographic space  1995. The criticality refers to their role as an essential foundation for the relatively plentiful and stable supply of food, consumer goods, and information. To disrupt them produces ripple effects not only in the region where it occurred, but extends outward  to the nation and the world.

         You will learn many basic concepts related to the earth in this article . If you study them well, it will definitely prove useful to you in future. 

Tides 

    If you stay near the coast for some time, you will realize that the sea water is sometimes very close to the coast while at other times, it is far away from the coast. We call these movements of the sea water 'tides'. Barring a few exceptions, all the coasts on the earth experience tides. High and low tides are natural phenomena. Let us try to understand the scientific reason behind these natural events. Tides are movements of sea water occurring daily and regularly. The level of sea water changes after a specific period of time. After every 12 hours and 25  minutes, a cycle of high tide and low tide gets completed. This regularly occurring event appears to be quite simple and natural, however, it is directly related to the sun, the moon and the earth and the gravitational and centrifugal forces that interact between them.

      In all the above activities, the effect of the centrifugal force is visible. The centrifugal force acts in the direction opposite to the gravitational force. Centrifugal means going away from the Centre. You must have experienced it too. At the local fairs if you sit in a Ferris Wheel, your seat spins and leans outward away from the wheel. This also is an effect of centrifugal force. Due to its rotation, the earth gets a type of power or force. This force works away from the Centre. It is called centrifugal force. Due to this force any object on the earth would be thrown into the space. However, the gravitational force is working towards the Centre of the earth at the same time. This force is many times greater than the centrifugal force. Hence any object on the surface of earth remains at the place where it exists.

Tides : The gravitational pull of the moon and the sun as well as that of the earth. The moon is closer to the earth than the sun, hence its gravitational force becomes more effective than that of the sun. Tides occur due to the relative positions of the moon, the sun and the earth A place on the earth located at the opposite point of the place experiencing high or low tide also experiences high or low tide respectively at the same time. This is a result of the centrifugal force. TRY TO UNDERSTAND THE LOCATIONS OF HIGH AND LOW TIDES ON THE  EARTH.

Types of Tides : As the timing of the tide varies every day, the range of a tide also keeps on changing. Generally the highest high tide occurs on full moon and new moon days whereas on the days of the first and the third quarter, the high tide is at its minimum. Spring tides and neap tides are the two types of tides.

Spring Tide : On new moon and full moon days, the gravitational pull of the sun and the moon act in the same direction. Due to this, the total pull increases. Hence the tide on these days is much higher than the average high tide. This is known as spring tide. As the bulge at the high tide is greater, the water at low tide recedes much more. The water level during spring tide is higher than the average high tides and lower than the average low.

Neap Tide : While revolving around the earth. the moon makes a right angle with respect to the earth and the sun, twice a month. This position occurs on the first and the third quarter of each month. On both these days, the forces of both the sun and the moon operate at night angles on the earth. At the places where the sun causes high tide, the gravitational pull of the moon which is at right angles also acts on the sea water Due to such conditions, the water level rise is less than usual at the time of high tide. Similarly, fall in water level is less than usual at the time of low tide. This is because the attraction of the sun and the moon are not complementary but at right angles to each other. Such tides are called neap tides. Neap tides are a little lower than the average high tides and a little higher than the average low tides. 

Do You Know ? The difference in the water level of the high tide and the low tide is called tidal range. In open seas, this range is about 30 cm. However, towards the coastal areas it goes on increasing. Along the coast of Peninsular India the range is around 100 to 150 cm for most of the part. The highest tidal range in the world is observed at Bay of Fundy along the Atlantic Coats of North America. Here the tidal range is about 1600 cm. In India, the highest tidal range is in the Gulf of Khambhat. It is about 1100 cm.

Effects of Tides 

• With the high tide, fish move into the creeks and this helps fishing activity.
• The tides clear the waste and hence the coasts become clean.
• Ports do not get filled with sediments.
• Ships can move up to the ports during high tide.
• During high tide, sea water can be stored in salt pans from which salt can be obtained.
• The tidal force can be used to generate electricity.
• A lack of an understanding of the timings of high and low tides may cause accidents to swimmers entering the sea.
• The tides help in maintaining the mangroves and the coastal biodiversity.

Timings of the tides change daily :  The tides are continuously occurring phenomena. After reaching the maximum water level during high tide, the low tide sets in. Similarly, after reaching the lowest water level during low tide, the high tide sets in. Remember that in the following discussion the highest limit of the high tides is mentioned. 

• There will be high tide at point 'P' as it is opposite to the moon.
• As point 'F' is opposite (at an antipodal location) to the point 'P', it will also experience high tide at the same time.
• It will take 24 hours for point 'P' to come back to its original position (360• ) Point 'P' will be at point 'F' after 12 hours (180•). 
• The same change will also occur with reference to the point 'F'.
• Point 'F' will not experience the same high tide, because in the meanwhile the moon also would have moved a little ahead (approximately 6•  15'). Hence it will take 25 minutes more for the point  'F' to come to the position opposite to the moon.

Waves :

 If you blow air over hot milk or tea, while drinking, ripples are generated on the milk or the tea. In the same way, because of the force of the wind, water appears to be moving. The sea water gets pushed by the wind and rippled are generated on the water surface. These are called waves.  The sea water moves up and down or slightly forward and backward due to the waves. The waves bring the energy contained in them to the coast. They break in the shallow waters near the coast. Large or small waves are formed continuously at the surface of the sea. Generation of waves is a natural and regularly occurring phenomenon too.

Structure of the Waves : The sea water get pushed up and down because of the wind. The raised up portion of a wave is called crest and the depressed one is called trough. If a strong wind is blowing in one direction, large waves are generated.  The vertical distance between a crest and the following trough is called the amplitude of the wave whereas the distance between two successive crests or throughs is called wave length. The wave length, its amplitude and its velocity depend on the velocity of wind.

Velocity Of Waves :

 We feel the waves are coming towards the coast. If a floating objects is thrown at a distance in the sea, we find the object moving up and down at the same place. It does not come to the coast. It means the water forming the wave also does not come to the coast. Remember that the water in the wave does not move, what moves is the energy. The main reason of wave generation is wind, but at times, due to earthquakes or volcanic eruptions occurring below the floor of the sea, waves get generated. Such waves assume a great height in the shallow waters near the coast. These waves are very destructive. They cause huge loss of property and life. These waves are called tsunamis. In 2004, Tsunami waves were generated because of the earthquake that took place near Sumatra island of Indonesia. They devastated the east coast of India as well as Sri Lanka.

Antipodal Point : A point that is located diametrically opposite to a given point. Such a point is fixed with reference to an imaginary line in the form of the diameter of the earth. For any or every point on the surface of the earth, there exists an antipodal point on the earth's surface.

Tsunami : Huge sea waves generated as a result of earthquakes occurring below the sea bottom. Tsunami waves cause tremendous loss of life and property in the coastal region where they strike.

Always Remember - If earthquake occurs in the ocean, the coastal areas face a risk of tsunamis. In such cases, it is better to go away from the coasts or towards higher altitudes. This way, loss of life can be avoided.

Do You Know ? While moving along the sea coast or playing in the water we must take adequate care regarding the timings of the tides otherwise it can lead to serious accidents. For that we must know the timings of the tides. For this you must know the phase of the moon on the given day. Three - Fourth of the phase of the moon is the time of the high tide. For example, suppose you are at the coast on the fourth phase of the moon, then three fourth of the phase is three. It means the high tide will occur at 3 am and 3 pm, and approximately 6 hours from, it, that is, 9 am and 9am will be the low tide. There may be slight differences according to local conditions. We must collect the information from local people and learn from them about the structure of the coast, its slope, rocky areas as well as the streams near the coast before entering the sea waters for enjoyment.

Conclusion: This post introduces the children to their natural, social and cultural environment. It attempts to develop the students' skills of problem solving and application and a healthy attitude towards the environment.