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1、The strong earthquake hit Japan,IntroductionTime:2:46 pm local time,March 11,2011 Place:Near Japans northeastern Honshu IslandDepth:about 10 km Magnitude:9.0 in the Richter scale(It has been the largest earthquake in Japan over 140 years.)Disaster:The strong earthquake hit Japan and resulted in 10-m
2、etre tsunami and serious nuclear leakage accident,causing heavy casualties and property losses.As at 18:00 on March 20,Japans quake and tsunami have left 8277 people dead and 12,722 missing.,Disaster Site,Nuclear Leakage,Fire Disaster,Significant earthquakes in the vicinity of Japan,（From Jan.1996 t
3、o Jul.2006）,Source:http:/www.seisvol.kishou.go.jp/eq/higai/higai1996-new.html,magnitude,Depth(km),Then,what is earthquake?,Naturally occurring earthquake,An earthquake is the result of a sudden release of energy in the Earths crust that creates seismic waves(地震波).This energy is released as a combina
4、tion of radiated elastic strain seismic waves,frictional heating of the fault surface,and cracking of the rock,thus causing an earthquake.,occur anywhere within the earth where there is sufficient stored elastic strain energy.,increasing stress,stored strain energy around the fault surface.,until th
5、e stress has risen sufficiently to break through the asperity.,suddenly allowing sliding over the locked portion of the fault,releasing the stored energy.,Earthquakes are recorded with a seismometer（地震检波器）,also known as a seismograph（地震仪）.,Deep focus earthquakes,The majority of tectonic earthquakes
6、originate at depths not exceeding tens of kilometers.In seduction zones,where older and colder oceanic crust descends beneath another tectonic plate,Deep focus earthquakes may occur at much greater depths(up to seven hundred kilometers).,Earthquakes often occur in volcanic regions and are caused the
7、re,both by tectonic faults and by the movement of magma in volcanoes.Such earthquakes can serve as an early warning of volcanic eruptions.,Sometimes a series of earthquakes occur in a sort of earthquake storm.On adjacent segments of fault,these storms occur over the course of years,and with some of
8、the later earthquakes as damaging as the early ones.,Effects of earthquakes,Shaking and ground rupture Main effects.Principally resulting in more or less severe damage to buildings or other rigid structures.The ground-shaking is measured by ground acceleration.,Landslides and avalanchesEarthquakes c
9、an cause landslides and avalanches,which may cause damage in hilly and mountainous areas.FiresFollowing an earthquake,fires can be generated by break of the electrical power or gas lines.In the event of water mains rupturing and a loss of pressure,it may also become difficult to stop the spread of a
10、 fire once it has started.,Soil liquefactionSoil liquefaction occurs when,because of the shaking,water-saturated granular material temporarily loses its strength and transforms from a solid to a liquid.Soil liquefaction may cause rigid structures,as buildings or bridges,to tilt or sink into the liqu
11、efied deposits.TsunamiUndersea earthquakes and earthquake-triggered landslides into the sea,can cause Tsunami.See,for example,the 2004 Indian Ocean earthquake.,FloodsFloods may be a secondary effects of earthquakes,if dams are damaged.Earthquakes may cause landslips to dam rivers,which then collapse
12、 and cause floods.Human impactsdisease,lack of basic necessities,loss of life,higher insurance premiums,general property damage,road and bridge damagecollapse of buildings or destabilization of the base of buildings which may lead to collapse in future earthquakes.,An earthquake prediction is a pred
13、iction that an earthquake in a specific magnitude range will occur in a specific region and time window.Predictions are considered as such to the extent that they are reliable for practical,as well as scientific,purposes.,Although there is evidence that at least some earthquakes in some tectonic reg
14、imes are predictable with useful accuracy of time and space,the reliability and reproducibility of prediction techniques have not been established and are therefore generally not accepted by seismologists.,What to do?,Family earthquake drill(heavy furniture supported archway)(windows hanging object
15、mirror fireplace)Indoors drop,cover,hold away from glass,windows,walls,In a moving car stop and pull it to the side of the road,stay in the car avoid stopping near or under buildings,trees,overpasses Be trapped under debris Do not light a match Do not move Cover your mouth,Thank you very much for your kind attention!,
