Chapter 1: Living with Tectonic Hazards

Chapter 1: Living with Tectonic HazardsPart 1: Hazards of the world

Copy when you see the star2016 Pure GeographyNotes

What is a Natural HazardEarthquakesVolcano eruptionTsunami

EarthquakeIs it possible for Singapore to experience an earthquake?When tremors occur near fault lines, energy is moved along the crust in waves.Such energy when sufficiently strong will travel long distances.Over distance, the energy will reduce.If there is a massive earthquake in Indonesia, we will feel it in Singapore.

Watch video on youtube (news report on Sgp experiencing tremors April 2012) click on lightning to open link.http://www.youtube.com/watch?v=7Eb8xYbF_Po

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What the Japanese are trained to do.Take a look at the next video. Pay attention to the specific action that the Japanese people do in the event of an earthquake in the following locations.HomeWhen drivingAt the shopsYou will have to answer the worksheet after watching the video so pay attention.

Video on Japanese emergency action training http://www.youtube.com/watch?v=IaedDlN5dfo Watch once, then at kids request restart at techniques (around 3 min mark) before giving exercise.4

Lets now attempt the exerciseYou have 10 minutes to answer the questions on the handout.Good luck!

What is the structure of the Earth?CoreMantleCrustRead up on Pg 7 in your textbook

Tectonic PlateThe crust of the earth.Two general typesContinental plateLess Dense, lighterOceanic plateDenser, heavier

Continental DriftTheory that crustal plates are constantly movingConvectional currents move in the mantle due to the variations of temperature.Warmer magma near the core rises, pushing the crust above to the sides before sinking down upon losing the temperature.

Draw Continental Drift Theory Diagram.8

Continental Drift Diagram

Evidence of Continental Drift TheoryThe changing shape of earths land mass over earths history shows that the plates are moving.The current location of the continents on earth will continue to change.

http://www.youtube.com/watch?v=ryrXAGY1dmE1m 14 sec vid on continental drift10

Continental Drift Diagram

SRP WorkWatch the following video on Colliding ContinentsAnswer the questions in the SRP handout / complete the groupwork

http://www.youtube.com/watch?v=KCSJNBMOjJs50 mins National Geographic video

Types of plate boundariesConvergent plate boundaryDivergent plate boundaryTransform plate boundaryRefer to pg 9 textbook

Divergent platesOceanic Oceanic divergenceArea where two oceanic plates move away from each otherMagma moves up to the surface and cools to form new oceanic crust Mid-Atlantic RidgePossible to find underwater volcanoes at such locations.

Draw oceanic divergent plate diagram15

Diagram of Divergent plate boundary(insert water surface for oceanic)

SeaMid Atlantic RidgeOceanic PlateOceanic PlateRising Magma

Continental Continental divergenceArea where two continental plates move away from each other Magma moves up to the surface and cools, forming new land.Often fractures form at the plate boundary, forming a linear depression (rift valley)Great African Rift Valley

Draw diagram of continental continental divergence17

Diagram of divergent continental plates

Great African Rift ValleyDivergent Continental Plate (Somalian)Divergent Continental Plate (Nubian)Rising Magma

Exercise TimeWhat do you think is needed to answer this question? With the aid of diagram (s), explain the different types of divergent plate boundaries that you have learnt. Give specific examples.Use Foolscap paper, complete your diagrams and short explanations with examples.Diagrams in pencil please.

Part 2: Convergent plates

Plate movementsIf there are plate boundaries that are diverging, at the end of that plate, there will be convergence.3 common types of convergent boundariesOceanic vs Oceanic plateOceanic vs Continental plateContinental vs Continental plate

Reasons for convergencePlates converge due to continental drift.As the plates are pushed apart, they crash into one another.Generally, the denser plate will subduct (sink) below the less dense plate.The plate that is riding above will buckle (fold) and massive landforms will occur.

Video on Oceanic vs Continental plate, buckling, forming mountains and Tsunami occuring prior to reset.http://www.youtube.com/watch?v=ep2_axAA9Mw22

Oceanic CrustsBeneath deep oceansBetween 5km and 8kmConsists of basaltVery dense and heavyMade of young rock (200 million years ago)

Continental CrustBeneath the earths land massesBetween 30-60 kmConsists of lighter rock, like graniteWide range of rock ages, from recent to over 4 billion year old.

Oceanic-oceanic plate boundariesWhen two oceanic plates convergeDenser plate subducts under the less dense plateArea where it subducts is called the subduction zoneA depression in the sea floor occurs at the subduction zone and is called a deep sea trench. (The Mariana Trench)Volcanic islands can also be formed at such boundaries

Oceanic-oceanic plate boundaries

Oceanic-Continental plate convergenceWhen an oceanic plate converges with a continental plate.The dense oceanic plate is forced down into the mantle.A deep sea trench is often formed at the subduction zone.The continental plate folds and forms fold mountains and volcanoesVolcanoes tend to be a result if melted magma is able to rise up through cracks in the crust back to the surface.`

Oceanic-Continental plate convergence

http://www.youtube.com/watch?v=7LgZThrw9DMWatch from 7.00 to 8.00 to see deformed diagram and misguided truth about Japanese Trench.28

Continental-Continental plate convergenceWhen two equally dense continental plates converge.There will still be a subduction occurring for one of the plates. However there is a large amount of friction built-up before it occurs.The strong force generated also causes folding.At such plate boundaries, large mountain ranges tend to form. (Himalaya)

Continental continental plate convergence

Transform boundaryOccurs when plates slide past one another horizontally.Huge energy released when friction is overcomeLarge massive earthquakes experiencedSan Andreas Fault (California)

Click on picture to show 3 min vid on San Andreas Fault (National Geographic)http://www.youtube.com/watch?v=ZxPTLmg0ZCwWatch also the next clip on the damage to roads to LA after 94 quake click on Agent Phttp://www.youtube.com/watch?v=mcoHJHo8d6kFinal additional clip of a classroom destroyed during a quake http://www.youtube.com/watch?v=FW-TkpvKPl033

Exercise time

Take a look at the handout (exercise 2).Using the information you have learnt so far, answer the question to the best of your abilities.

Good luck

Refer to Unit 1 Ex 2 (map of plate boundaries and Qn on possible phenomena at 3 such boundaries).34

Review Comparison Table

Part 3Landforms commonly associated at tectonic boundaries

Fold Mountains

Fold MountainsThe rock layers on the crust are constantly exposed to pressureWhen they are compressed, they fold, forming fold mountains.To upfold is called the anticline and downfold is called the syncline.

Fold MountainsThe major ranges are along convergent plate boundariesThe rocky mountainsHimalayasSwiss AlpsPg 22

Rift Valleys / Grabens

Rift ValleysNear divergent plate boundaries, plates pull apart, causing land displacement.The downward displacement forms rift valleys.Found commonly along divergent boundariesAlso called GrabenEast African Rift Valley

Rift Valley diagram

Block Mountains / Horst

Yosemite National Park

Block MountainsWhen sections of the crust are pulled apart by tensional force, some parts are ripped off.The downward displaced areas are the rift valleysThe blocks left behind form block mountains with steep sides.Also called Horst

Block Mountain diagram

Volcanoes

Click on picture to watch 2 min vid on top 10 active volcanoes in the world

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VolcanoesLandform formed by magma ejected from the mantle.Magma builds up in the earths crust to form a magma chamber.With repeated layering of ejected magma, the volcano grows in heightFound a divergent and convergent plate boundaries where there is subduction.

Vents are openings in the earths surface with a pipe leading into the magma chamberWhen magma is ejected onto the surface, it is called lava. There is no change in composition.Vulcanicity refers to the upward movement of magma in the crust and onto the surface.

Lets take a short Brain BreakTake a look at the video on Mt St Helens in AmericaHalf the volcano was blown off in the eruption

Watch 6min vid on Mt St Helen eruption 1980s.http://www.youtube.com/watch?v=-H_HZVY1tT450

ViscosityThe stickiness of the lavaThe resistance of the lava to flowingHigh viscosity flows slowlyLow viscosity flows quicklyViscosity of the lava determines the volcanos shape

Honey high viscosityWater low viscosity51

2 Key types of VolcanoesShield VolcanoesComposite Volcanoes (Stratovolcanoes)

Shield Volcanoes

Shield VolcanoesGentle sloping sides and a broad summitLow-silica lava (low viscosity) presentLava flow is fast, spreading out quicklySubsequent layering leads to wide base with low overall height.Mount Washington in America

Stratovolcanoes

StratovolcanoDeveloped from successive eruptions.Ash and lava (coarse fragment) accumulate over time.Layers of ash are locked in by subsequent layers of lava.Tall volcanoes with concave bases formed.Secondary cones may develop as magma from the vent seeps into the sides of the cone and erupts.Pyroclastic flow common Hot rock fragments and superheated gases.Mount Pinatubo, Philippines

Mt Pinatubo

Watch video on Mt Pinatubo eruption Human impact

http://www.youtube.com/watch?v=NQzGjGKdGvQ (4 min)

Or

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Distribution of volcanoesPacific Ring of Fire is the most active volcanic activity occursMany earthquakes and volcanic eruptions occur along the ring of fireRing is along several converging plates (Pacific, Nazca, Philippines, Australian and Eurasian plates)Volcanoes can also form where plates diverge.Pg 29

Pacific Ring of Fire

Watch video on Pacific ring of fire (10 mins)

http://www.youtube.com/watch?v=YqSJDNi7Qzw 59

Volcanic EruptionsVolcanoes fall into 3 statesActiveDormantExtinct

Active Volcano Constant volcanic activity Currently undergoing eruption or are expected to erupt in the future.Mt Pinatubo, Philippines; Mt St Helens, America.

Dormant VolcanoCurrently inactive but may erupt in the near futureProlonged period of no volcanic activityInner magma chamber still hot and activeMt Fuji, Japan

Extinct VolcanoVolcanoes without current seismic activityNo geological evidence of eruption in the past thousands of years.Almost no risk of eruption.Lake Toba, Indonesia

Risks of living near volcanic areasDestruction by volcanic materialsLandslidesPollutionEffects on weather

Destruction by volcanic materialsLava, rock fragments, volcanic bombs (ejected molten lava blobs)Extreme temperatures of projectiles and lava flow, destroying and killing.Inhaling hot gases and ash can also lead to injury and death.With pyroclastic flow, speeds above 80km/hr can be achieved, making it impossible to escape.

The loss people of Pompei

Watch 2.25 min video footage of the plaster cast people of Pompei

http://www.youtube.com/watch?v=8P352045O-o

Highlight that these people were instantly turned into plaster casts by the pyroclastic flow.66

LandslidesCollapse of a volcanic cone during eruption.Downward displacement of previous slide of volcano.Causes large scale damage to infrastructure and loss of life.Settlements near the volcano may get wiped out totally.

Landslide

Watch video on the landslide after Mt St Helens eruption

http://www.youtube.com/watch?v=UK--hvgP2uY

2 min vid68

PollutionAsh particles and gases released disrupt human activities over long distances.Some gases (Carbon monoxide, Sulphur dioxide, etc) are harmful to humansFine ash particles captured in the air endanger planes and cause large monetary loss due to grounding of flights.

Pollution

Watch FOX news rpt on Iceland volcanic eruption grounding flightshttp://www.youtube.com/watch?v=RCWp1fGP_6M3 minsAlJazeera clip on Heathrow opening and passengers stranded in SGP flying backhttp://www.youtube.com/watch?v=WfcTMlP5UTA70

Effects on weatherSulphur dioxide reacts with water vapour in the atmosphere.The particles reflect the suns energy back into space.This leads to a cooling of surface temperatures on earth.Fall in global temperature might affect plant and animal life.

Lets attempt an exercise on what we have covered.15 - 20 minutes,Complete all the questions in Foolscap / space providedGood luck

Issue Ex 5 on the negative effects of living near a volcano72

EarthquakesCaused by sudden release of stored energy due to movements of crustal plates.Occurs along faultlines as pressure builds up stress and when the plates slip, earthquakes are formed.

Key Earthquake TermsSeismic waves energy that is released by earthquakes.Focus the point in the crustal plate where the seismic energy originates. Epicentre point above the Focus on earths surface. Most of the energy released travels along the surface of the earth.

Aftershocks subsequent smaller earthquakes that follow after a major earthquake. Could continue to occur months after the initial earthquake.Some aftershocks might be as powerful as the original earthquake.

Depth of FocusThe depth of focus affects the impact felt on the surface.2 key typesDeep-focus earthquakesShallow-focus earthquakes

Depth of focusDeep-focus earthquake70 to 700km below surfaceSmaller impact on landMost of seismic waves lose their energy as they reach the surface.

Depth of focusShallow-focus earthquake70km and above in the crustGreater impact on land Seismic waves reach surface quickly and with more energy.

Measurement of earthquakesRichter scale (Pg31 in textbook)

9?? Destruction impacts thousands of kilometers of land

Watch view of destruction post earthquake in Christchurch(2min)http://www.youtube.com/watch?v=opsiKirDfdENews report on Christchurch massive quake (response by gvt)(1:30 min)http://www.youtube.com/watch?v=wBq1-qZWmhM

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Factors affecting earthquake damagePopulation DensityLevel of PreparednessDistance from epicentreTime of occuranceSoil type

Population densityHigh population density affects more peopleTendency for high-rise buildings increases damageHigher literacy rate in cities mean higher chance of better preparedness.Higher chance of survivalBetter evacuation plans, trained rescue workers.

Level of preparednessProper public training and social awareness leads to less panicRepeated practice of emergency exercise leads to familiarity of actionEmergency preparedness kits raise possibility of survival

Earthquake Preparedness

Watch NZ video on Earthquake Preparedness(4min)http://www.youtube.com/watch?v=-a7T9Uf-JB483

Distance from the epicentreSeismic energy weakens as the distance increases from the epicentre.Locations further away from the epicentre suffer less from the earthquake.

Watch clip on tremors in SGP (who is our buffer?) Indonesia!

http://www.youtube.com/watch?v=7Eb8xYbF_Po84

Time of occuranceTime of earthquake determines what people are doing and whether they are able to react.At night, people are asleep. There is less time to react.In the day, survivors of an earthquake are able to avoid subsequent accidents.

Watch video of damage of 7.2 Christchurch earthquake 2011. End of vid, ask students to think if it had happened in the middle of the night, what might the death toll be looking at the look of the damage in the video?

http://www.youtube.com/watch?v=jlykXk82BlY

(3min)85

Type of soilLoose and unconsolidated (not packed tightly) soil move more in times of an earthquake.Impact on the buildings on the surface is greater. Damage is often worse.Liquefaction loose soil flowing like water.Danger of landslides after earthquakes cause more harm.

Watch short clip on liquefaction (45 secs)http://www.youtube.com/watch?v=qmVYbjiNWds

Alternate vid (forward to 50s) to watch the video of liquefaction.http://www.youtube.com/watch?v=PwvvYxSZ7PI86

Earthquake zonesTendency for earthquakes to occur along crustal plate margins. Tendency for earthquakes to be caused when subduction along destructive plates or slipping of transform plates

Earthquake Zones

Hazards of living in earthquake zonesTsunamisDisruption of servicesFireLandslidesLoss of livesLoss of property

TsunamisTsunami an unusually large sea waveFormed by sudden movement of sea floorPossible causesEarthquakes at subduction zonesExplosive underwater volcano eruptionUnderwater landslideLarge coastal landslides

TsunamisAs the displaced water moves, it gathers strength and size.When it hits the coast, large destruction is resulted.

Pic on left (vid) that shows 2004 Tsunami at Thailandhttp://www.youtube.com/watch?v=ntIwawAusDE

Pic on right (vid) of Bandar Aceh (initial earthquake and subsequent tsunami) 7 min. Worth watching!http://www.youtube.com/watch?v=ht_ZpSuJ6A491

Disruption of servicesLoss of electricity, gas and water leads to loss of essential services.Broken pipelines also raise the risk of explosions.Roads and railway destruction make it harder to send aid.

FireEarthquakes at timings where meals are prepared raise risk of fires.Gas pipes and electric cables that are broken lead to fire risk.Urban areas are densely populated, hence larger fire risk.

LandslidesShaking of earthquakes loosen soil.Along slopes and hills, original vegetation may no longer be able to hold soil.Landslides and mudflows cause large damage.Heavy rainfall after earthquakes raise the risk of landslides.

Destruction of property and Loss of livesEarthquakes destroy homes and buildings that are not earthquake proof.Large amount of money needs to be spent to rebuild the property.Urban areas with more infrastructure (roads, subways) cause even more money to repair.

Watch 3 min vid on Japanese earthquakehttp://abcnews.go.com/Archives/video/jan-17-1995-earthquake-japan-9421417

#nightearthquake #fire #JapanEarthquake #destruction95

Part 4Benefits of living near a Volcano

4 key benefits of living near volcanoesFertile soilPrecious stones and minerals, building materialsTourismGeothermal energy

Fertile SoilLava and ash breakdown to form fertile volcanic soilsThe richest soils on earth, highly favourable for agricultureHawaii and Bali

Video of rice fields in Bali

http://www.youtube.com/watch?v=Z83XgZzEOpY99

Precious stones and building materialsVolcanic rocks can be rich in precious stones and minerals.After the top layers of volcanic rocks are eroded, these can be extracted.The volcanic rocks at Kimberley, South Africa, are the richest source of diamonds globally.Other useful materials like sulphur can be collected from volcanic rocks. Sulphur is used to refine sugar and make matches and fertilisers.

Watch video on blood diamonds , negative effect of having diamonds in the ground

http://www.youtube.com/watch?v=0hCl_RXqoZk102

Tourism Volcanic areas have dramatic landscapes.Scenery attracts tourists for hiking and camping.Volcanic areas are rich in history and attract visitors too. The ruins of Pompeii, Italy. The black beaches in Bali

Geothermal EnergyWhen groundwater comes in contact with the hot rocks underground, it heats up and escapes as steam.This can be harnessed to produce Geothermal Energy.Large turbines are used to complete this process.Iceland uses Geothermal energy to power over 70% of their homes.

Watch video on Geothermal energy production

http://www.youtube.com/watch?v=rfUQy86ZMpQ106

Part 5 : Responses to EarthquakesO Level only

Why do people live in such places?Favorable living conditionsFertile soil conditions for agriculture.No alternative location to live in.Case of no choice

Review QuestionTurn to pg 47 of your textbook.Using that map, lets answer the questions in the handout.

3 approaches to earthquakesFatalistic approachAcceptance approachAdaptation approach

Fatalistic approachPeople who accept earthquakes as unavoidable.Tend to resist evacuation in the face of an earthquake.Common for communities in less developed countries with limited access to other places.People who live near Mt Pinatubo.

Acceptance approachPeople who accept the risk of living in earthquake-prone areas due to the benefits of living in that area.Benefit outweigh the costs of moving away.Mostly accepted by the developed countries.People of Christchurch.

Adaptation approachPeople who successfully live in earthquake-prone areas as they are well prepared.Use of earthquake monitoring devices, risk assessment, technology to increase earthquake resistance.Costly approach but able to save many lives and property.People in Taiwan and Japan.

Responding to earthquakesPreparedness measuresLand use regulationsBuilding designInfrastructure developmentEmergency drills Use of technology

Suitability of preparedness measuresUse of specific measure / package of measures dependent on factorsAffordability of implementationEducation level of populationAvailability of resourcesSuitability of application

Short-term responses The immediate responses that a country needs to adopt upon experiencing the disaster Handling the status of the affected zonesSearching and rescuing casualtiesProviding medical aid, food and waterSetting up emergency sheltersCalling for humanitarian aid (international aid)

Long-term responsesPost disaster action to prevent / alleviate impact of future potential disastersImproving infrastructureCompensation of land and property loss.Ensuring the economic recovery of the affected regionManaging health options (psychological impact)

There is no single quick fix solution to any natural disasters. Every situation and condition and location is different and the dynamic situation needs to be dealt with based on the resources available at the moment of the disaster.

The End