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Introduction The characteristic of acts of nature Earthquakes Flooding Flooding and landslips
Acts of nature? These are the various natural phenomena causing sudden infringements of normal ability to live of the population, and also destruction and destruction of material assets. They quite often have negative influence on surrounding nature. Earthquakes usually concern acts of nature, flooding, earth flows, landslips, snow drifts, eruptions of volcanoes, collapses, droughts, hurricanes, storms. Fires in some cases can be carried to such disasters also, especially mass wood and peat. Dangerous disasters are, except that, industrial failures. Special danger is represented by failures at the enterprises of the oil, gas and chemical industry. Acts of nature, fires, tsunami... On a miscellaneous it is possible to meet them. Perplexed, even it is doomed, as centuries people met various disasters, or is quiet, with staunch belief in own forces, with hope of their taming. But confidently accept a call of disasters those can only who, knowing how to operate in these or those conditions, signs the correct decision is unique: will rescue itself, will assist another, will prevent, how much can, destroying action of forces majeure.
As acts of nature understand the natural phenomena (earthquakes, flooding, landslips, avalanches, have sat down, hurricanes, cyclones, typhoons, fires, eruptions of volcanoes, etc.), having extreme character and leading to infringement of normal activity of the population, ?destruction of people, destruction and destruction of material assets. Acts of nature can arise as independently from each other, and in interrelation: one of them can cause another. Some of them often result not always from reasonable activity of the person (for example, wood and peat fires, industrial explosions in mountain district, at building of dams, a bookmark (working out) open-cast mines that frequently leads to landslips, avalanches, collapses of glaciers and etc.).
Earthquakes? These are the strong fluctuations of earth crust caused by the tectonic or volcanic reasons and leading to destruction of buildings, constructions, to fires and human victims. The basic characteristics of earthquakes are: depth of the centre, magnitude and intensity of energy on an earth surface. Depth of a seismic centre usually is in limits from 10 to 30 km, in some cases it can be much more. The magnitude characterises the general energy of earthquake and represents the logarithm of the maximum amplitude of displacement of soil in the microns, measured on seismogram on distance of 100 km from epicentre. The magnitude () on Richter changes from 0 to 9 (the strongest earthquake). Its increase at unit means tenfold increase of amplitude of fluctuations in soil (or ground displacement) and increase in energy of earthquake in 30 times. So, amplitude of displacement of soil of earthquake with М=7 in 100 times more, than with М=5, thus the general energy of earthquake increases in 900 times. Intensity of energy on an earth surface is measured in points. It depends on depth of the centre, magnitude, distance from epicentre, a geological structure грунтов and other factors. For measurement of intensity of energy of earthquakes in our country the 12-mark Richter scale is accepted.
Earthquakes put the big material damage and carry away thousand human lives. So, for example, as a result of catastrophic earthquake by intensity of 8 points in the Richter scale on June, 21st, 1990 in the north of Iran in a province of Giljan was lost over 50 thousand persons and about 1 million persons have appeared wounded and dishomed. (Earthquake scales in Armenia are shown on the fly-leaf.) One and a half thousand villages are destroyed. 12 cities have considerably suffered, 3 from which are completely destroyed. Earthquakes cause also other acts of nature, such as landslips, avalanches, have sat down, a tsunami, flooding (because of break of dams), fires (at damage of oil storages and rupture of gas pipelines), damages of communications, lines energo - water supply and the water drain, failure at the chemical enterprises with the expiration (flood) СДЯВ, and also on the atomic power station with leak (emission) РВ in atmosphere, etc.
Flooding? These are considerable floodings of district as a result of water level lifting in the river, lake, a water basin, caused by the various reasons (spring снеготаяние, loss of plentiful storm and rain deposits, ice jams on the rivers, break of dams, завальных lakes and protecting dams, wind нагон waters, etc.). Flooding on carry are huge also a material damage and lead to human victims. The direct material damage from flooding consists in damage and destruction of inhabited and industrial buildings, automobile and railways, electric mains and communication, meliorative systems, ?destruction of cattle and a crop of agricultural crops, damage and destruction of raw materials, fuel, a foodstuff, forages, fertilizers, etc.
As a result of the storm rains which have passed in Transbaikalia in the beginning of July, 1990, there were unknown in these parts high waters. It is taken down more than 400 bridges. According to the regional extreme freshet commission, the damage in 400 million roubles is caused to a national economy of the Chita region. Thousand people remained without a roof over the head. Has not managed and without human victims. Flooding can be accompanied by fires owing to breakages and short circuit of electrocables and wires, and also ruptures of water and sewer pipes, the electric, television and cable cables which are in the earth, because of the subsequent non-uniform ground deposits.
Torrential rains, thawing of a snow cover and glaciers can be the reason of flooding and landslips. About 40 % of natural accidents it is necessary on flooding. Landslips bring the greatest damage to the settlements which are on high coast of the rivers, and cities most of all suffer from flooding and the villages located in valleys of the rivers. In some regions the flooding which are a part of a natural cycle, for example as in a valley of Nile, provide steady agriculture. The agriculture of many tropical countries depends in many respects on the flooding caused by monsoonal rains. Sudden flooding and high waters on the rivers, arising at passage of atmospheric fronts and the cyclones causing rains in considerable territory are more dangerous быстроразвивающиеся, or. The mountain relief, dry soil, small speed of moving of zones of intensive deposits can be aggravating factors. Strong storm rains can cause a high water even in deserts. The dry caked soil is capable to absorb only a small amount of deposits, and rain water quickly transforms the dried up channels of the rivers into rough streams. In deserts of the North America of more people has sunk, than was parched with thirst, same it is possible to tell and about some northern areas of Africa. Sudden rain high waters are frequent and in cities, where many the levelled surfaces covered with asphalt and concrete. They promote increase in a superficial drain of rain water which quickly floods streets. Many big cities are constructed on coast of the rivers, therefore during high waters thousand people can suffer. So, in June, 1992 one of areas of Paris has been flooded, and during flooding of 2002 in Europe one city has suffered not.
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