Although natural disasters are caused by nature and there is nothing that we can do to prevent them happening, there are many different natural causes that lead to natural disasters, and being aware of these causes enables us to be better prepared when such disasters do arrive. One common natural disaster is flooding, which occurs when a river bursts its banks and the water spills out onto the floodplain. This is far more likely to happen when there is a great deal of heavy rain, so during very wet periods, flood warnings are often put in place.
There are other risk factors for flooding too: Drainage basins of impermeable rock also cause the water to run faster over the surface. Earthquakes are another common natural disaster that can cause many fatalities. These plates do not always move smoothly and can get stuck, causing a build-up of pressure. Thank you for understanding! Please, enter email address. Essay on Natural Disasters. What were the most catastrophic natural disasters of the 20th century?
Is there anywhere that is safe from natural disasters? Could a super volcano like Yellowstone plunge the world into an ice age? What is the most powerful natural disaster? Are long term droughts the worst natural disasters? Why are we not better protected against natural disasters?
Can we predict earthquakes? Why do we still build cities along fault lines? What causes mudslides and similar disasters What is the worst natural disaster you can imagine? Writing Paraphrasing Editing Proofreading Formatting. Please accept our Terms. Your message has been successfully sent! We will get back to you soon. Our Activity in The sudden release of stored elastic energy causes earthquakes. Earthquakes in India are caused by the release of elastic strain energy created and replenished by the stresses from the collision between the Indian plate and the Eurasian plate.
The most intense earthquakes occur on the boundaries of the Indian plate to the east, north and west. In the Indian plate, faults are created when this rubs against the Eurasian plate.
When an earthquake occurs along a fault line within the plate, it is called an intra-plate earthquake. The majority of the earthquakes occur along plate boundaries. Earthquakes are also caused by volcanic activity. Construction of large water reservoirs may also cause earthquakes—these are called reservoir-induced earthquakes. The movement of the plates and occurrence of earthquakes seem to be concentrated in certain areas or zones of the earth. Based on intensity and frequency of occurrence, world map is divided into the following earthquake zones or belts—.
These represent the eastern and western margins of the Pacific Ocean respectively. The occurrence of maximum number of earthquakes in this region is due to four ideal conditions—. Also called the Mediterranean Belt or Alpine-Himalayan Belt, it accounts for about 21 per cent of the total seismic shocks.
The epicentres of this region are along the mid-Atlantic Ridge and the islands near the ridge. This belt represents the zone of moderate and shallow focus earthquakes—the reason for this being the creation of transform faults and fractures because of splitting of plates followed by their movement in the opposite direction. Based on seismic data and different geological and geophysical parameters, the Bureau of Indian Standards BIS had initially divided the country into five seismic zones.
There is thus no part of the country that can be termed earthquake free. Of the five seismic zones, zone V is the most active region and zone I shows least seismic activity.
The entire north-eastern region falls in zone V. One of the reasons for this region being prone to earthquake is the presence of the young-fold Himalayan Mountains here which have frequent tectonic movements.
Zone IV which is the next most active region of seismic activity covers Sikkim, Delhi, remaining parts of Jammu and Kashmir, Himachal Pradesh, Bihar, northern parts of Uttar Pradesh and West Bengal, parts of Gujarat and small portions of Maharashtra near the west coast.
The remaining states with lesser known activity fall in zone II. The high seismicity of the Indian subcontinent arises from the tectonic disturbances associated with the northward movement of the Indian plate, which is underthrasting the Eurasian plate. The Himalayan region has been the site for great earthquakes of the world of magnitude greater than 8.
The high seismicity region extends from Hindukush in the west to Sadiya in the northeast which further extends down to the Andaman and Nicobar Islands. Different institutions including the Indian Meteorogical Department and the Indian School of Mines, have after a study of mechanics of several earthquakes in the north- eastern region found that the thrust faulting was generally indicated along with Dawki fault and the Indo-Burma border.
Teiedemann, a member of the Earthquake Engineering Research Institute of the Seismological Society of America, said in that the increased interplay activity near the north-eastern boundary in the Indian plate coupled with thrusting of the Himalayan Burmese sector pointed to the danger of earthquakes in the region. There are three kinds of seismic waves.
Waves that move the fastest are called primary, or P, waves. These waves, like sound waves, travel longitudinally by alternate compression and expansion of the medium, like the movement of the bellows of an accordion. Somewhat slower are the secondary, or S, waves which propagate transversely in the form of snakelike wriggles at right angle to the directions of travel.
These cannot travel through liquids or gases. They rise to feet or more and cause damage when they break on habitated coasts. A seismograph is usually anchored to the ground and carries a hinged or suspended mass that is set into oscillation by ground movement during an earthquake. The instrument can record both horizontal and vertical ground movement in the form of wavy lines on paper or film. From the record, called a seismogram, it is possible to find out how strong the quake was, where it began and how long it lasted.
The location of the epicentre of a quake is determined from the time of arrival of the P and S waves at the seismographic station. Since P waves travel at a speed of about 8 km per second and S waves at 5 km per second, it is possible to compute the distance of their origin from the seismic record. If the distance from three stations are computed, the exact location can be pin pointed.
A circle of appropriate radius is drawn around each station. The epicentre lies where the circles intersect. The magnitude is a measure that depends on the seismic energy radiated by the quake as recorded on seismographs.
The intensity, in turn, is a measure that depends on the damage caused by the quake. It does not have a mathematical basis but is based on observed effects. Devised by the American seismologist, Charles Francis Richter, in , the Richter scale is not a physical device but a logarithmic scale based on recordings of seismographs, instruments which automatically detect and record the intensity, direction and duration of a movement on the ground.
The scale starts at one and has no upper limit. On this scale, the smallest quake felt by humans is about 3. The strongest quake ever recorded had a magnitude of 8. Richter magnitude effects are confined to the vicinity of the epicentre. The Richter scale has been immensely modified and upgraded since it was introduced.
It remains the most widely known and used scale for measuring the magnitude of an earthquake. For measurement of the intensity of an earthquake, the Modified Mercalli Intensity Scale is used. The point Mercalli scale measures the intensity of shaking during an earthquake and is assessed by inspecting the damage and interviewing survivors of the earthquake. As such, it is extremely subjective.
Furthermore, because the intensity of shaking varies from one place to another during an earthquake, different Mercalli ratings can be given for the same earthquake. Unlike the Mercalli scale, the Richter scale measures the magnitude of an earthquake at its epicentre. Aftershocks are earthquakes that often occur during the days and months that follow some larger quake. Aftershocks occur in the same general region as the main shock and are believed to be the result of minor readjustment of stress at place in the fault zones.
Generally, major quakes are followed by a larger number of aftershocks, decreasing in frequency with time. Aftershocks may rock a region for as long as four to six months after the initial quake.
However, strong ones last only a few days. Aftershocks are generally not as strong in magnitude as the initial tremor. But a small chance of them being stronger in magnitude cannot be ruled out, in which case the first and aftershocks become known as foreshocks. Earthquakes occur every day around the world. Each day there are about 1, very small earthquakes measuring 1 to 2 on the Richter scale.
Approximately, there is one every 87 seconds. Annually, on an average, there are quakes capable of causing damage with a magnitude of The science of earthquake prediction is at its infancy at present, even though several intensive attempts in this direction have been going on for the last two to three decades in the USA, Russia, Japan, China and India. In spite of some breakthroughs— the notable example being the prediction of the Haicheng earthquake of China 7.
For, just a year later in , the seismologists could not predict the Tangshan earthquake. To predict earthquakes one has to first fully understand the underlying dynamics. For example, even though it is known that this intense seismic activity is a result of the north-northeastern movement and under thrusting of the Indian plate, it is not known what fraction of the strain energy is being released by earthquakes along the belt.
Aside from such dynamic imputs, an empirical basis of prediction can be founded by recognising, monitoring and interpreting observable and decipherable precursory phenomena. Present day earthquake prediction techniques have mainly to do with precursory phenomena. The parameters that are normally looked at include electrical resistivities, geomagnetic properties, variation in the ratio of compressional to shear wave velocities, etc.
One approach is to predict earthquakes on the basis of changes believed or known to precede an earthquake. Such earthquake precursors include abnormal tilting of ground, change in strain in rock, dilatancy of rocks which could be measured by a change in velocities, ground and water levels, sharp changes in pressure, and unusual lights in the sky.
The behaviour of some animals is also believed to undergo a distinct change prior to an earthquake. Some lower creatures are perhaps more sensitive to sound and vibrations than humans; or endowed with what one may call prescience. Another approach is to estimate the probabilistic occurrence of an earthquake statistically by relating the past occurrences to weather conditions, volcanic activity and tidal forces.
There have been some notable Indian efforts too in developing prediction models in the Himalayan-belt context. One relates to the so- called seismic gaps, which postulates that great earthquakes rupture the Himalayan arc whose total length is about km. Proponents of this model have postulated that the entire Himalayan detachment would rupture in years, the rupture being caused by a 8.
This hypothesis forms the basis for the apprehension of the Tehri dam being subjected to earthquakes of this magnitude. Some scientists have noted that certain cycles of low and high seismicity characterise the Alpide belt. For example, after an extremely active cycle from to , with 14 earthquakes of magnitude greater than 7. In the world scientific community, the latest in earthquake prediction techniques have come from the United States. One method developed by the Americans involves the use of laser beams.
These beams are shot from an observatory to a geostationary satellite in space. On hitting the satellite, the waves are reflected back to the observatory. A substantial difference in the time taken by the laser beams to travel between the two points is an indication of considerable tectonic plate movement, and perhaps an imminent earthquake.
A recent study of Indonesian reefs showed that corals record cyclical environmental events and could predict a massive earthquake in the eastern Indian Ocean within the next 20 years. Scientists said the earthquake could be similar to the magnitude 9. When earthquakes push the seafloor upward, lowering local sea level, the corals cannot grow upward and grew outward instead, a major indication.
An area off Sumatra that has been the source of disastrous earthquakes, still carries a lot of pent-up pressure that could result in another strong quake, noted the study reported in the journal Nature. It is not, however, clear as of now whether a precise earthquake prediction and warning system can be developed and put to any effective use. The greatest damage in an earthquake is caused by the destruction of buildings and resultant loss of life and property and destruction of infrastructure.
The earthquakes having the same magnitude on the Richter scale may vary in damage from place to place. The extent of damage that an earthquake can cause may depend on more than one factor.
The depth of the focus may be one factor. Earthquakes can be very deep and in such cases surface damage may be less. The extent of damage also depends on how populated and developed an area is.
The National Buildings Organisation of India lists weaknesses in burnt brick buildings as follows: 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.
Natural disasters happen all over the world, and they can be utterly devastating for people’s lives and the environments in which they live. Although natural disasters are caused by nature and there is nothing that we can do to prevent them happening, there are many different natural causes that lead to natural disasters, and being aware of .
Mar 11, · Natural disasters can range from volcanic eruptions to tsunamis, but the biggest killer is usually not the disaster itself (1(pg.1)). Natural disasters can have rapid or slow repercussions with serious health, social, and economic consequences (1(pg.1)).
The Disaster Management Act, was enacted for establishing requisite institutional mechanisms for drawing up and monitoring the implementation of disaster management plans, and for undertaking a holistic, coordinated, and prompt response to . Your natural disasters essay will be much easier to write if you take the time to map out your outline first. Your outline allows you to understand what the structure of your 5/5.
This essay seeks to provide an overview of insurance specifically on assessment, measurement and management of both man-made risks and natural disaster risks. . Natural Disasters Essay Natural disasters are extreme, sudden events caused by environmental factors that injure people and damage property. Earthquakes, .