Large openings placed too close to the corners. Long rooms having long walls unsupported by cross-walls. Some measures to prevent building collapse during the earthquake are: The last one is the one feature that is most effective in ensuring the integrity of enclosures like a rigid box. For masonry construction, the BIS has specified that materials to be used should be well-burnt bricks and not sun-dried bricks.
The use of arches to span over openings is a source of weakness and should be avoided unless steel ties are provided. Scientists have suggested designing buildings to counter quake movement by shifting the centre of gravity with the help of a steel weight placed on the top of the buildings.
In this technique, thick, columns of concrete and steel are inserted metre deep into the soil beneath the regular foundation. In case of earthquakes, these pillars provide extra strength and prevent the buildings from collapsing.
During a quake, the rubber absorbs the shocks. In high-rises, enlarged structures on the top floors should be avoided. Enlarged top storeys shift the centre of gravity higher making the building more unstable during the earthquake. In cities, many buildings stand on columns. The ground floor is generally used for parking and walls start from the first floor.
These buildings collapse quickly during an earthquake. It is associated with fierce wind and heavy rainfall. Horizontally it extends from to km and vertically from the surface to about 14 km.
Severe tropical cyclones cause considerable damage to property and agricultural crops. The principal dangers posed are: Rainfall up to 20 to 30 cm a day is common. The highest ever sustained winds recorded in the case of tropical cyclones are kmph. Storm surge rise of sea level of four metres are common.
The highest sea level elevation in the world due to continued effect of storm surge and astronomical high tide occurred in near Bakerganj, where the sea level rose by about 12 metres above the mean sea level on that occasion. Tropical cyclones over the Bay of Bengal occur in two district seasons, the pre-monsoon months of April-May and the post-monsoon months of October-November. On an average, in fact, almost half a dozen tropical cyclones form in the Bay of Bengal and the Arabian Sea every year, out of which two or three may be severe.
Out of these, the stormiest months are May-June, October and November. Compared to the pre- monsoon season of May, June, when severe storms are rare, the months of October and November are known for severe cyclones. The IMD has published the tracks of the cyclones since and updates them every year in its quarterly scientific journal, Mausam. As 90 per cent of the deaths in severe cyclones all over the world occur in high storm surges accompanying them, the only feasible method to save the lives of human beings and animals is to evacuate them to safe inland cyclone shelters as early as possible after the receipt of advance cyclone warnings from the IMD.
The evacuation of people is difficult in flat coastal districts as in Bangladesh where the tides of six to 10 metres above the sea level submerges offshore islands and travels inland for considerable distances.
This is a narrow belt at the equator, where the trade winds of the two hemispheres meet. It is a region of high radiation energy which supplies the necessary heat for the vaporisation of sea water into the air.
This moist unstable air rises, generates convective clouds and leads to an atmospheric disturbance with a fall in surface atmospheric pressure. This causes a convergence of surrounding air towards this region of low pressure. The converging mass of air gains a rotary motion because of what is known as the Coriolis force caused by the rotation of the Earth. However, under favourable circumstances, such as high sea-surface temperatures, this low pressure area can get accentuated.
The convective instability builds up into an organised system with high-speed winds circulating around the low pressure interior. The eye has an average radius of 20 to 30 km. It can even be as much as 50 km. Given the existing scientific knowledge about cyclones, it is not yet possible to physically dissipate the buildup of a massive cyclone.
Cures are generally worse than the disease. For example, while seeding by sodium iodide crystals has been attempted in some parts of the world— with marginal success—a more effective prescription proposed sometimes is a nuclear explosion. Obviously, that would be trading one disaster for an even greater one. Accepted technology, therefore, only provides the capability to detect and track cyclones with sophisticated satellite imagery and ground- based radar systems.
But here too the limitations are glaring. Atmospheric science, for example, is not yet in a position to unambiguously predict the motion and behaviour of a cyclone more than 24 hours ahead of its arrival. So all that is possible in that brief span is to warn the vulnerable sections of the population of the imminent danger and adopt measures to move them to safer cyclone withstanding structures.
The frequency, intensity and coastal impact of cyclones varies from region to region. Interestingly, the frequency of tropical cyclones is the least in the north Indian Ocean regions of the Bay of Bengal and the Arabian Sea; they are also of moderate intensities.
But the cyclones are deadliest when they cross the coast bordering North Bay of Bengal coastal areas of Orissa, West Bengal and Bangladesh. This is mainly due to storm surges tidal waves that occur in this region inundating the coastal areas.
Over the last two-and-a-half centuries, 17 of the 22 severe tropical cyclones—each causing loss of more than 10, human lives—took place in the North Bay of Bengal. While gales and strong winds, as well as torrential rain, that usually accompany a cyclone can cause sufficient havoc to property and agriculture, loss of human life and cattle is mainly due to storm surges.
If the terrain is shallow and shaped like a funnel, like that of Bangladesh—much of the exposed land is just about at the mean sea level or even less—storm surges get enormously amplified.
Coastal inundation due to a combination of high tide and storm surge can cause the worst disaster. India has an efficient cyclone warning system. Tropical cyclones are tracked with the help of i regular observation from weather network of surface and upper air observation stations, ii ships report, iii cyclone detection radars, iv satellites, and v reports from commercial aircraft.
Ships of merchant fleet have meteorological instruments for taking observations at sea. The range of these radars is km. When the cyclone is beyond the range of coastal radars, its intensity and movement is monitored with weather satellites. Warnings are issued by the area cyclone warning centres located at Kolkata, Chennai and Mumbai, and cyclone warning centres at Bhubaneswar, Visakhapatnam and Ahmedabad. This consists of the following elements:.
Typically, in a cyclone the maximum devastative effects are within about km from the centre and on the right of the storm track where all the islands lie. Evacuating the population just 24 hours before would require an army of high speed boats, an unfeasible proposition for a resource—poor country. The obvious solution, therefore, would be to provide a large number of storm shelters in the particularly vulnerable areas. So inured are we to the annual phenomena of floods in season, that one more village practically washed away by a flash flood causes no more than a ripple.
But for the people there it is a traumatic experience. Earlier, it used to be done by a conventional method—gauge to gauge or discharge correlation by which future gauges at forecast points are estimated on the basis of gauge discharge observed at some upstream station.
Gradually, other parameters like precipitation, etc. Nowadays, computer-based hydrological models are being used for inflow and flood forecasting. The basic information required for flood forecasting is rainfall data of the catchment area of the river.
Due to poor communication and inaccessibility, complete information is not always available. However, with sophisticated high-powered S-band radars, it is now possible to estimate the rainfall in an area of up to km around the radar site. This system is used extensively in the US for estimating the rainfall potential in the catchment areas of major rivers an issue of flood forecast warning.
The use of radar for the precipitation estimate is based on the principle that the amount of echo return from a volume of cloud depends on the number and size of hydrometeros in it. The empirical relationship between the echo return and the rainfall rates has been developed for various types of rain.
Using fast switching digital circuits, the return video is digitised, integrated, normalised and contoured into standard six or seven rainfall rates. Observations taken every ten minutes can be cumulatively added and averaged to give hour rainfall prediction over the region.
Through appropriate modes, the information from a number of radar sites can be sent to a central office where powerful computers process the data and yield the overall rainfall potential of the weather system. The advantage of using radars for hydrological work lies in the fact that the information over the inaccessible region is available without actual human intervention.
Of course, there are many assumptions which do not always hold good, thereby introducing large errors in the result. But with suitable calibration with actual gauge measurements correction factors could be applied. This has not helped much as population has moved into areas where flooding used to occur and has been controlled due to structure.
Whenever flooding level is higher than what the structure can hold, the result is devastating. The non-structural approach calls for removing populations from the flood plains. Another important aspect is to reduce the silting of rivers. Afforestation in the catchment areas, along the river banks, helps in maintaining the effective river volume. But it is evident that, over the last four decades or so, flood control efforts have proved counter-productive because they have not included adequate planning for conservation of watersheds.
As a result the increasing siltation of rivers is accelerating their rate of flow in flood, eventually forcing even well built embankments to give way. As is well known, embankments increase the force of the river by channelling it over a narrow area instead of permitting it to spread.
The danger of relying too heavily on the system of embankments for flood control has been well documented. Apart from the depletion in forest cover, overgrazing contributes greatly to soil loss in the catchment areas.
Even in the mountainous areas, where efforts have been made to plant trees on steep slopes to reduce the soil loss during rains, mountain goats have impeded the process of regeneration. Cattle and goats also destroy the plant cover that springs up after the rain which is crucial for holding down the soil. Human activity is yet another factor. Quarrying, road construction, and other building activity in sensitive catchment areas add to the soil loss. As a result of all these factors, the silt load of many rivers has increased greatly.
The siltation level of dams, which has generally been underestimated at the time of construction has had to be revised by 50 to per cent in some cases. Siltation reduces the capacity of reservoirs. Consequently in order to save the dam, unscheduled and panic releases of water are resorted to often without giving adequate warning to people downstream who live in the path of the released water.
Thus ironically dams built partly to assist in flood control, are today contributing to the devastation caused by floods. The phenomenon that really ought to engage the minds of planners is how and why the flood-prone area in the country is increasing each year. Even areas which have never known floods in the past are now affected. The NFC estimates that 40 million hectares are flood-prone of which 32 million hectares can be protected. Some such Centrally-sponsored schemes are: The Central government provides special assistance to the Border States and north eastern states for taking up some special priority works.
A tsunami is a series of travelling ocean waves which are set off by geological disturbances near the floor of the ocean.
The waves of very, very long wavelengths and period rush across the ocean and increase their momentum over a stretch of thousands of kilometers. Some tsunamis may appear as a tide but they are not tidal waves in reality. While tides are caused by gravitational influences of the moon, sun and the planets, tsunamis are seismic sea waves. That is, they are related to an earthquake- related mechanism of generation. Tsunamis are usually a result of earthquakes, but may be at times caused by landslides or volcanic eruption or, very rarely, a large meteorite impact on the ocean.
The tsunami can be understood at the basic level by looking at the series of concentric ripples formed in a lake when a stone is thrown into it. A tsunami is like those ripples but caused by a disturbance much greater in magnitude. Tsunamis are shallow-water waves different from the wind-generated waves which usually have a period of five to twenty seconds which refers to the time between two successional waves of about to metres. They have a period in the range of ten minutes to two hours and a wavelength exceeding km.
The rate of energy loss of a wave is inversely related to its wavelength. So tsunamis lose little energy as they propagate as they have a very large wavelength. So they will travel at high speeds in deep waters and travel great distances as well losing little energy. A tsunami that occurs metres deep in water has a speed of km per hour. At m, it travels at Ion per hour. It travels at different speeds in water: As an average ocean depth of m is assumed, one talks of tsunamis as having an average speed of about km per hour.
The long gravity tsunami waves are caused by two interacting processes. There is the slope of the sea surface which creates a horizontal pressure force. Then there is the piling up or lowering of sea surface as water moves in varying speeds in the direction that the wave form is moving.
These processes together create propagating waves. A tsunami can be caused by any disturbance that displaces a large water mass from its equilibrium position.
An undersea earthquake causes buckling of the sea floor, something that occurs at subduction zones, places where drifting plates that constitute the outer shell of the earth converge and the heavier oceanic plate dips below the lighter continents. As a plate plunges into the interior of the earth it gets stuck against the edge of a continental plate for a while, when stresses build up, then the locked zone gives way.
Parts of the ocean floor then snap upward and other areas sink downward. In the instant after the quake, the sea surface shape resembles the contours of the seafloor. But then gravity acts to return the sea surface to its original shape. The ripples then race outward and a tsunami is caused.
There were 17 tsunamis in the Pacific from to which resulted in 1, deaths. During a submarine landslide, the equilibrium sea-level is altered by sediment moving along the floor of the sea. Gravitational forces then propagate a tsunami. Again, a marine volcanic eruption can generate an impulsive force that displaces the water column and gives birth to a tsunami. Above water landslides and objects in space are capable of disturbing the water when the falling debris, like meteorites, displace the water from its equilibrium position.
As a tsunami leaves deep waters and propagates into the shallow waters, it transforms. This is because as the depth of the water decreases, the speed of the tsunami reduces.
But the change of total energy of the tsunami remains constant. With decrease in speed, height of the tsunami wave grows. Tsunami attacks can come in different forms depending upon the geometry of the seafloor warping that first caused the waves.
Sometimes, the sea seems to at first draw a breath but then this withdrawal is followed by arrival of the crest of a tsunami wave. Tsunamis have been known to occur suddenly without warning. The water level on the shore rises to many metres: Waves can be large and violent in one coastal area while another is not affected. Areas can be flooded inland to metres or more; when tsunami waves retreat, they carry things and people out to sea.
Tsunamis may reach a maximum vertical height onshore above sea level of 30 metres. The size of the tsunami waves is determined by the quantum of deformation of the sea floor. Greater the vertical displacement, greater will be the wave size. For tsunamis to occur, earthquakes must happen underneath or near the ocean. They must be large and create movements in the ocean floor. Subduction zones off Chile, Nicaragua, Mexico and Indonesia have created killer tsunamis. The Pacific among the oceans has witnessed most number of tsunamis over since One of the deadliest tsunamis occurred in Asia on December 26, It was triggered by the most powerful earthquake recorded in the past four decades—one whose magnitude was 8.
A tsunami with a magnitude 9. Tsunamis and earthquakes can cause changes in geography. The Andaman and Nicobar Islands may have moved by about 1. The warning of an oncoming tsunami cannot be obtained by merely detecting an earthquake in the seas; it involves a number of complex steps which have to be completed in a systematic and quick fashion.
It was in , that the international warning system was started. Computer systems at the Pacific Tsunami Warning Centre PTWC in Hawaii monitor data from seismic stations in the USA and elsewhere warning is issued when an earthquake is shallow, located under the sea or close to it and has a magnitude that is more than a pre-determined threshold.
Each gauge has a very sensitive pressure recorder on the sea floor in which can detect the change in the height of the ocean it even if it is by just one cm. The data is transmitted acoustically to a surface buoy which then relays it over satellite to the warning centre. There are seven DART gauges deployed at present and four more are being planned.
PTWC has improved its performance rapidly as high-quality seismic data has been made available to it. The time it needed to issue a warning has fallen from up to 90 minutes some six years ago to 25 minutes or even less today.
The Indian Ocean is not prone to tsunamis. Only two have occurred in this ocean including one on December 26, India has been a leader in the initiative to develop a reliable tsunami warning system for the ocean. It has decided to set up a sophisticated system for detecting deep sea movements and develop a network with the countries in the Indian Ocean region for sharing information on tsunamis.
It will have pressure sensors to detect the water movement. The sensors will be linked to the satellite that will relay information to the earth station. Some more sensors would be installed later and the data buoys would be linked to the system that would record changes in the water level. The Indian government plans to set up a network with Indonesia, Myanmar and Thailand which would calculate the magnitude and intensity of tsunamis from the data available to it.
DART-type gauges will be installed by the government and it will join 26 countries in a network that warn each other about tsunamis. A state-of-the-art National Tsunami Early Warning Centre, which has the capability to detect earthquakes of more than 6 magnitude in the Indian Ocean was inaugurated in in India.
The system comprises a real-time network of seismic stations, bottom pressure recorders BPRs , and 30 tide gauges to detect tsunamigenic earthquakes and monitor tsunamis.
Some hurricanes have less impacts on the environment while there those that are too strong and cause ma. A tornado is a violent windstorm usually characterized by a twisting, funnel shaped cloud that is caused by a thunderstorm or a hurricane. It is produced when a cool air mass meets a warm air mass and forces the warm air mass to rise over the cool air mass very rapidly.
Most of the damage from a tornado is a result of high wind velocity and wind blown debris. Most tornadoes occur during the months.
Being in a natural disaster is a fearsome thing, but if you have a planned ahead the shock won't be as great. Having a plan is important for many reasons. Saving valuables may seem minor, but some things are very hard to live without. You will definitely need something to communicate with and some clothing. Natural disasters occur quickly, so keeping valuables in a safe box is a very good. Earthquakes are frequent in Japan.
A survey showed that seismic disturbances, mostly of minor nature, occurred more than three times a day. Geological research has shown that, possibly under the continuous impact of these disturbances, the western coast of the Japanese islands is settling, while the Pacific coast is rising.
The most disastrous earthquake in Japanese history occurred in Brazil is a country overwhelmed by natural, and human, disasters. Natural disasters, such as flooding, drought, mudslides and epidemics, happen frequently. Also, deforestation in the northern region is an ongoing occurrence. The close proximity to the Amazon and the Atlantic Ocean cause many horrible events to happen in this South American country. Drought is the natural disaster in Brazil th.
Nature is a beautiful thing. Without nature, there is nothing in this world. Nature gives many wonderful things to mankind. Though nature gives many things to mankind sometimes it shows its creepy side. Earthquakes are one of the terrible outcomes of nature. Earthquakes cause dreadful effects like property damage, loss of life and food shortage. Earthquakes cause property damage by destroying. Have you ever been in a very frightening thunderstorm, or tornado? I have and I was amazed and scared at the same time.
I don't mind storms and I often find them fun, unless they become dangerous. I have found the weather in the the state of North Dakota to be unpredictable and often harmful. Summer storms in this prairie state are frequent and chaotic; sweeping across the plains without warning,.
According to the National Hurricane Center, a hurricane releases heat energy at a rate of 50 trillion to trillion watts, which is equivalent to the energy from exploding 10 megaton bombs every 20 minutes. With such strength, it is no wonder why these natural disasters have such large destructive impacts on the environment. Furthermore, hurricanes are of extreme importance to Florida, since the. Forest fires, whether natural or otherwise e. As a result, families and pets are losing their homes and their lives.
Clearing out underbrush and picking up small, dead plants can help decrease the chance of a forest fire. Fire is one of the planets most destructive forces, it destroys all who block. Climate change is among the principal dangers facing people this century and ocean levels are increasing dramatically. This essay will first suggest that the biggest problem caused by this phenomenon is the flooding of homes and then submit building flood protection as the most viable solution. The foremost problem caused by sea levels creeping up is the flooding of peoples' residences.
Do you ever wonder why the weather seems unpredictable these days? One day sunny, one day snowy? The unpredictability of the weather is caused by global warming, or climate change.
Global warming is caused by the gradual increase in Earth's average temperature LiveScience. Climate scientists agree on the primary cause of global warming. According to Karl, Melillo, and Peterson, the atmosphere is. In the rainy season rivers and canals are full to the brim. Sometimes water rises so high that it overflows the banks. Fields, and sometimes houses, lie under water. This great rise of water is called a flood. The flood is caused in many ways.
Sometimes rain falls heavily for days together. The rain water of mountains flows down the river. Sometimes the river cannot hold so much water.
It was the worst rainy weather I had seen. The skies remained overcast as sheets of rain poured down without stopping. In the evenings, the rain was usually accompanied by blinding flashes of lightning and deafening peals of thunder. Most of the residents in my area remained confined indoors. Apart from people scurrying to and from work and school, there was little outdoor activity.
Floods are there every year in India. During rainy season from July to September, many parts of the country suffer from devastating floods. Flood is one of the major calamities that afflict the country regularly. Floods result in much havoc and vast scale destruction of life and property. India can very proudly boast of an extensive network of rivers.
They are the very life-giving natural gifts. The prominent issue of flooding caused by excessive littering should be addressed and rectified. It is quite essential and beneficial to resolve such conflict since it can impact utterly negative on society.
Flooding can be caused by numerous reasons. Littering however, have tended to be quite dominant. Floods are caused by many things. Many times it rains too much, other times a dam breaks; however, the effects of floods devastating.
Floods can cause environmental losses as well and economical losses, land is washed away, homes are ruined, and people sometimes even die. This essay is about the causes and effects that flood have on our world. Floods are caused by many t. It was the worst rainy weather that I had seen. In the evenings, the rain usually accompanied by blinding flashes of lightning and deafening peals of thunder.
Devastation, mass destruction, and fear are all adjectives associated with the word earthquake. Previously this year, many witnessed the agony and anxiety the people in Japan faced as their country was demolished with a natural disaster. This event has sparked one question in Californians' minds: Is California prepared for such a disaster? More importantly, are you prepared?
It is the opinion o. Imagine a giant mountain burping out tons of ash and magma at a height of 33 km, and now imagine that the ash and magma hit your city, killing you, and burying everything in sight.
Pretty terrifying image, right? Well, unfortunately, the ancient people of Pompeii in 79 A. D didn't have to imagine that. Mount Vesuvius is a volcano that has erupted over 50 times, volcanoes have many physical traits t. The time I watched twister it was so interesting.
The storm chasers in the movie were creating a machine that has little ball things inside. The things inside fly up into the tornado and the calculate the information on the tornado. This movie got me interested in wanting to learn more about tornadoes. A tornado is a natural disaster where mother nature kills or injures people and destroys houses.
Floods have been reported as the most frequent natural disasters all around the world. Their effects are far-reaching and costly. The main cause of floods is the natural weather condition. Flooding will be mainly caused by heavy and steady downpour.
Depending on the terrain and soil of the area, flooding may occur. In the low-lying areas, the streams are narrow and thus heavy downpour may fill the. There are flood stories from many cultures. The flood stories usually consist of a higher power that floods a civilization due to some act that has made the higher power angry. The stories talk about one specific family and how the flood consumes the entire globe. So many cultures have a story about a great flood that have many similar details that it is hard to not believe that it is not true, bu.
The Fukushima nuclear disaster touched people around the world. The concern for the citizens of Japan was matched by the fear of the potential dangers of other nuclear reactors.
One of the most common natural disasters, but also one of the most commonly forgotten, is wildfires. These take place in many different countries all over the world, particularly .
This essay seeks to provide an overview of insurance specifically on assessment, measurement and management of both man-made risks and natural disaster risks. The essay further highlights the formulas adopted in measuring man-made risks.
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The responses to natural disasters have been to invest in early warning systems that tend to protect lives and properties (FEMA, Disasters ). People should manage natural disasters by bringing new emphasis to research, preparedness, response, and recovery. Mar 18, · A 'natural disaster' is a major event resulting from natural processes of the Earth. It causes a great loss of life and property. During such disasters, the number of people who are rendered, trippled and houseless is more than the number of people who loose their lives. Even the economy of the place which faces a natural disaster, gets Author: All Essay.