Tlp 2019 phase 2 day 44 - IASbaba...TLP Phase 2 – Day 44 Synopsis 2019 Page 1 1. Explain the correlation between plate tectonics and earthquakes with the help of suitable examples

TLPPhase2–Day44Synopsis 2019

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1.Explainthecorrelationbetweenplatetectonicsandearthquakeswiththehelpofsuitableexamples.Introduction:According to the theory of plate tectonics, theearth’slithosphereisbrokenintodistinct plateswhich are floating on aductilelayercalledasthenosphere(upper mantle). The tectonic plates) vary fromminorplatestomajor plates,continental plates(Arabian plate) tooceanic plates(Pacificplate), sometime acombinationof both continental and oceanic plates (Indo-Australianplate).Body:Themovementofthesecrustalplatescausestheformationofvariouslandformsandistheprincipalcauseofallearthmovements.Earthquakesareadirectconsequenceofinteractionbetweenvariouslithosphericplates.

Divergenceformingdivergentedgeortheconstructiveedge:

• Theplatesdivergeormoveawayfromeachother.Here,thebasalticmagmaeruptsandmovesapartgivingrisetoseafloorspreading.

• Earthquakes(shallowfocus)arecommonalongdivergentedges.• Example:EastAfricanRiftValley,Mid-AtlanticRidge,minorearthquakesnear

AzoresandIcelandetc.



Convergenceformingconvergentedgeordestructiveedge:

• Plates move towards each other at a boundary. This type of is calledaconvergentboundary.

• There aremainly threeways inwhich convergence can occur: between anoceanicandcontinentalplate;betweentwooceanicplates;andbetweentwocontinentalplates.

• These boundaries tend to produce most of the earthquakes that havemagnitudes greater than 6.0, andsubduction zonesproduce the deepestearthquakes.

• ExamplesincludedeepoceantrencheslikethePeru–Chiletrench,HimalayanBoundaryFault,Andesetc.

Conservativeedgeortransformfault:

• Inthiskindofinteraction,twoplatesgrindagainsteachotherandthereisnocreation or destruction of landform but only deformation of the existing



landform. [Crust is neither produced nor destroyed as the plates slidehorizontallypasteachother].

• Transform boundaries typically produce large, shallow-focus earthquakes.Althoughearthquakesdooccurinthecentralregionsofplates,theseregionsdonotusuallyhavelargeearthquakes.

• ExamplesincludetheSanAndreasFaultandtheAnatolianfault,earthquakesclosetoandinCalifornia.

Conclusion:Seismologistsassociatedifferentkindsofseismicactivitywithwhatishappeningatdifferent types of plate boundaries. The theory of plate tectonics can be used toprovide a simplified explanation of the global distribution of earthquakes, theirevolution and provide a background research for sustaining loss and resistivemeasures.2.Whatareblizzards?Howdo theygetoriginated?Howare theydifferent fromavalanches?Discuss.IntroductionAblizzardisaseveresnowstormwithstrongandpowerfulwindsinexcessof35mphformore than 3 hours and visibility of less than a 1/4mile.During a blizzard, thetemperatureisoftenbelow0degrees,becauseofthisfrostbiteandhypothermiaarecommon.Body



Originationofblizzards:

• Cold air (below freezing): In order for there to be snowfall, the airtemperaturebothupinthecloudsanddownatgroundlevelmustbecold.Iftheairtemperatureiswarmneartheground,thesnowwillmeltbeforethereachesthegroundcausingraininstead.

• Moisture: This is known as water vapour. An excellent source of watervapour iswhentheairmustblowacrossa largebodyofwater, suchas theocean.Astheairsblowsoverthewater,somewater isevaporated intotheair.Thisiswatervapour.

• Warm, risingair:Warmairmustriseovercoldair inorderforablizzardtoform. This can happen in twoways. The wind can pull warm air from theequatortowardsthepoles,andcoldairfromthepolestowardstheequator.When warm and cold air meet, a front is formed which results inprecipitation. If warm air rises up a mountaintop it can cool as it rises,formingcloudsandblizzardsnows.

EffectsofBlizzards

• Ablizzardhastheabilitytoputacityintostandby,sometimesevenfordays.Itcanmakedrivingconditionsimpossibleandresultsinkidsnotbeingabletoget to school as well as adults not being able to get towork. This in turnmeansschoolandbusinessescloseandpeoplearehousebound.

• Low air pressure during a blizzard can make breathing difficult for somepeople.

• Electrical wires can be damaged resulting in a loss ofelectricityto homes.Peopleareleftwithouttheuseofcomputers,TV’s,appliances,andlights.

• Blizzards are life threatening and people have lost their lives because ofthem.

• 8.Blizzardshurt the economy as businesses losemoneywhen people can’tgettowork.

• 9.Whentransportroutesandshopscloseduringablizzardthereisachanceoffoodandwaterscarcityiftheblizzardlastsforanextendedperiodoftime.

Blizzard Avalanche

• It is a severe snowstorm,especiallywith strongwinds andgreatlyreducedvisibility.

• Rarelyoccurs.• Blizzard is a very strong, bitterly

cold. wind accompanied bymasses of powdery snow or icecrystalsoftenwithpoorvisibility.

• Blizzardsareathigheraltitude.

• It is anevent thatoccurswhenacohesive slab of snow lying uponaweaker layer of snow fracturesandslidesdownasteepslope.

• Frequentlyoccurs.• Avalancheisaswiftmovementof

snow, ice, mud, or rock or amixture of them down amountainsideorslope.

• Avalanches are can be seen atloweraltitudetoo.



• Occuronlyinwinter.• Causes: (1) cold air (2) moisture

(3)warmair.• Main types: mountain blizzard,

ground blizzard and large scalefrontalblizzard

• Can occur in spring, autumn andwinter.

• Causes: (1) a pre-existing weaklayer,and(2)atrigger.

• Maintypes: loose-snow (orsluff)avalanchesandslabavalanches

ConclusionUnder the effects of climate change, mountainous regions across globe areundergoing fast andwell-perceptible evolutions, which are attracting the growingattentionofpeople, scientistsandmanagers.Tocopebetterwith thehazardsandvulnerabilitiesspecifictargetsandlongtermplansaremust.3.What are tornadoes?Howdo theyoriginate?Aren’t they similar to cyclones?Examine.IntroductionAtornadoisaviolentlyrotatingcolumnofairthatextendsfromathunderstormtothe ground. It is a vortexof rapidlymoving air. A tornado formswhen changes inwindspeedanddirectioncreateahorizontalspinningeffectwithinastormcell.Thiseffectisthentippedverticalbyrisingairmovingupthroughthethunderclouds.Body



Windswithin the tornado funnelmayexceed500kmph.High velocitywinds causemost of the damage associatedwith theseweather events. Tornadoes also causedamage throughairpressure reductions. Theairpressureat the tornado centre isapproximately800millibars(averagesea-levelpressureis1013millibars)andmanyhumanmade structures collapse outward when subject to pressure drops of thismagnitude.DistributionofTornadoesintheworld:



Origin:

• Tornadoformationtypicallyneedsthefouringredients:shear,lift,instability,andmoisture.

• Wind shear is the most important factor that plays into the creation oftornadoes.When there iswind shear, sometimes thesewinds begin to rollintoahorizontalcolumnofair.

• Onceyougeta strongupdraftof airbeing transported from theground totheatmosphere, thatcolumnofairbecomesvertical.That iswhenastormusuallydevelopsinthisscenario.

• As the stormdevelops, it turns into a supercell thunderstormmuch of thetime.Thesesupercellthunderstormsareseparate,discretecellsthatarenotpartofalineofstorms.Also,supercellsarestormsthatrotateandspin.Withboth the vertical, rotating column of air and the supercell thunderstormtogether,thatmaybringdownatornadofromthestormcloud

• Tornadoesaremost common in springand least common inwinter. Springandfallexperiencepeaksofactivityasthosearetheseasonswhenstrongerwinds, wind shear, and atmospheric instability are present. Tornadooccurrenceishighlydependentonthetimeofday,becauseofsolarheating.

• United States has the most violent tornadoes. At any moment there areapproximately1,800thunderstormsinprogressthroughouttheworld.

DifferencesbetweenTornadoandcyclone



Tornado cyclone

Definition Atornadoisarotatingcolumnofair ranging inwidth fromafewyardstomorethanamileand whirling at destructivelyhigh speeds, usuallyaccompanied by a funnel-shaped downward extensionof a cumulonimbus cloud.Winds40-300+mph.

A cyclone is an atmosphericsystem of rapidly circulatingair massed about a low-pressure centre, usuallyaccompaniedby stormyoftendestructive weather. Stormsthat begin in the SouthernPacificarecalledcyclones

Rotation Clockwise in the southernhemisphere and counterclockwise in the northernhemisphere

Clockwise in the southernhemisphere and counterclockwise in the northernhemisphere.

Formsofprecipitation rain Rain,sleet,andhail

Frequency The United States recordsabout 1200 tornadoes peryear, whereas theNetherlands records thehighest number of tornadoesper area compared to othercountries. Tornadoes occurcommonly in spring and thefall season and are lesscommoninwinters

10-14peryear

Location Tornados have been spottedin all continents exceptAntarctica

SouthernPacificOcean,IndianOcean. Cyclones in thenorthwest Pacific that reach(exceed) 74 mph are"typhoons".

Occurrence Places where cold and warmfronts converge. Can be justalmostanywhere.

warmareas

ConclusionTornadoes as well as cyclones both occur in India. However, unlike cyclones thefrequencyof tornadooutbreak isvery low.Cyclonesoriginate in theBayofBengalregion aswell as in the Arabian Sea regionwhere as Tornadoes ofweak strength



occur innorth-westernandnorth-eastern regionof the country causing significantdamagetomanandmaterial.4.Whichpartoftheglobearemoresusceptibletodamagebycyclonesandwhy?Explainwiththehelpofsuitableexamples.IntroductionCyclones are low pressure centres, surrounded by closed isobars, which involve aclosed circulation about the low pressure centre. The air moves anticlock wise innorthernhemisphereandclockwiseinsouthernhemisphere.They can be classified either on the basis of their geographical location (tropical/temperatecyclones)oronthebasisoftheirnature(cold/warmcorecyclone).Theyplay a vital role in exchange of heat between different latitude zones and alsotransferhumidityformonepartoftheearthtoanother.BodyRegionaldistributionoftropicalcyclones:

Therearesixregionsthataremorevulnerabletotropicalcyclones:

• Tropical North Atlantic (Gulf ofMexico,West Indies and Caribbean Sea):Cyclones in this region is known asHurricane, occurmainly duringAugust-October.Mainreasonsbeingincreasedseasurfacetemperature,convective



instability, lowwind shear and other thermodynamic activities. Examples-HurricaneKatrina,Florenceetc.

• Eastern part of the tropical north pacific (Western coast of Mexico andCentral America): also known as Hurricane, usually observed during June-July. The shifting of Intertropical Convergence Zone (ITCZ) northwards andlowpressureformed,aidedbynorthwestmovementofwind(duetoCoriolisforce)favourstheformationofTropicalCycloneinthisregion.

• Westernpart of tropical northpacific (ThePhilippines, theChina Seaandareas around Japan): The cyclones in this region are called as Typhoon,occursduringmonthsof June-December.Thepresenceof lowverticalwindshear of less than 10 metres/second, monsoon trough and atmosphericinstabilityfavoursdevelopmentoftropicalTyphoons.

• Bay of Bengal and Arabian Sea: They are more frequent during June-September, high sea temperature along with the low pressure regions,sometimes the typhoons originating in western pacific too help in cycloneformation.Ex-Fani,Ochkhietc

• WesternSouthPacificOcean(regionsofSamoa,FijiIslandandtheeastandnorthcoastofAustralia):OccurduringJanuary-Marchseason.Theytooareresultofhighsurfacetemperatureandlowverticalwindshearthatresultinatmosphericinstabilityandheavycloudiness.

• The south coast of IndianOcean (coastal regionsofMadagascar): Occursduring January-March and the westward movement of tropical depressionintensified by low vertical wind shear favours cyclone formation. Onedangerous recent event is the Idai Cyclone (March 2019) that resulted inmorethan1300deathsandseveralmissingcases.

Temperate cyclones are majorly dynamic in origin (Movement of air masses andcoriolis force-Frontogenesis), theyoccurduringwinterseasonsandareawayfromequator region. They are largely non-destructive due to slow moving winds, buttheremight be damage due to flooding. They can occur both on land andwater.Theyoccurscatteredbutirregularintervalsthroughoutthezoneofwesterlies.Theyimpact mainly in Northern hemisphere (due to less land availability in SouthernHemisphere).They impact Indianclimate in the formofWesterndisturbances.Though, theyarebeneficial, as theyaid inwheat, saffron cultivation, sometimes theyhavenegativeimplications too. Excessive rainfall causes landslides, floods, avalanches etc., andoccasionallybringscoldwaveanddensefoglikeconditionthatdamagesthecropinIndo-Gangeticplains.ConclusionAround8percentoftotallandareainIndiaispronetocyclones.Thecyclonicstormsare associatedwith heavy rains, thunderstorms, high tides and intensewinds thatcauseheavydestructionincoastalareas.ProperimplementationofNationalCycloneRiskMitigationProject(NCRMP) that include improvedearlywarningdissemination



system, capacity building of local communities to respond, and strengthening therehabilitationmechanismwouldminimizethedamage.5.Whatisvolcanism?Whatarethefactorsthat leadtovolcanism?Whatroledovolcanoesplayintheclimate?Introduction:Volcanismisthephenomenonoferuptionofmoltenrock(magma)ontothesurfaceoftheEarthorasolid-surfaceplanetormoon,wherelava,pyroclasticsandvolcanicgaseseruptthroughabreakinthesurfacecalledavent.Body:Movement ofmolten rock in themantle, caused by thermal convection currents,coupled with gravitational effects of changes on the earth's surface (erosion,deposition, even asteroid impact and patterns of post-glacial rebound) drive platetectonicmotionandultimatelyvolcanism.Factorsthatleadtovolcanism:

• Plate Tectonics: The majority of volcanoes occur where two lithosphericplatesconvergeandoneoverridestheother,forcingitdownintothemantletobereabsorbed.

• Ocean floor spreading:Amajorsiteofactivevolcanism isalong theaxisoftheoceanicridgesystem,wheretheplatesmoveapartonbothsidesoftheridgeandmagmawellsupfromthemantle.

• Weak Earth Surface: Because of high pressure in the earth’s interior, themagma and gases escape with great velocity as the pressure is releasedthrough eruptionswhere opportunity is provided byweak zones along theearth’ssurface.

• Faults:Wheneverextremepressurebuildsinthemantle,alongfaultlinesaneruptionislikelytohappennext.Theearthquakes,forinstance,mayexposefaultzonesthroughwhichmagmamayescape.

• Magma crystallization: Decreasing temperatures can cause old magma tocrystallize and sink to the bottom of the chamber and thismovement canforcefreshliquidmagmaupandout-similartodroppingabrickinabucketofwater.

• Adecreaseinexternalpressure:Adecreaseinexternalpressurecantriggeraneruptionasitmayminimizethevolcano'sabilitytoholdbackbyincreasingthepressuresinsidethemagmachamber

• Platemovement: Volcanismmayoccur becauseof platemovementover a“hot spot” fromwhichmagmascanpenetrate to the surface.Ex. IslandsofHawaii

Thegasesanddustparticlesthrownintotheatmosphereduringvolcaniceruptionshaveeffectsonclimate.



Negativeeffects:Volcaniceruptionsproducehazardouseffectsfortheenvironmentandclimate,

• Ashescanstayinthestratosphereforabouttwotofiveyears,andwithinthisperiod, there are chemical reactions that destroy the stratospheric ozonemolecules.

• Volcanoes contribute about18%-20%ofChlorineentering the atmosphere,thisalsodestroysozone.

• Volcanoesalsocauseglobalwarmingbyreleasinggreenhousegasessuchaswatervapourandcarbondioxideintotheatmosphere.

• Lavacankillplantsandanimals.Thisalsocontributes toglobalwarmingbyreducingcarbonsink.

Positive effects: Unlike other natural disasters such as floods, wildfires andearthquakes,volcanoescanhavesomepositiveeffects.

• Most of the particles spewed from volcanoes cool the planet by shadingincoming solar radiation. The cooling effect can last for months to yearscausingcoolingoverlargeareasoftheEarth.

• Some ash and lava breakdown become soils that are rich in nutrients andbecomegoodareasforcropplantingactivitiesandgrowthoftheforest.

Conclusion:Volcanism helps in the formation of various landforms on the earth's surface andbears both positive and negative effects on the climate, environment and humanlife.With scientific studies, one can predict the volcanic eruption tomuch extent.Preparednessforthisnaturaldisastercanprotecthumanlifeandenvironmenttoalargerextent.

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Tlp 2019 phase 2 day 44 - IASbaba...TLP Phase 2 – Day 44 Synopsis 2019 Page 1 1. Explain the correlation between plate tectonics and earthquakes with the help of suitable examples