Plate Tectonics and Associated Hazards

Plate Tectonics and Associated HazardsUnit 3 Section 1 : Plate Movement Structure of the Earth Tectonic TheoryPlate MarginsHot Spots1The CoreApproximately the size of MarsStarts about 2900km downCentre is 6350 km downThe most dense part of the planetMade up of rocks rich in iron and nickelCore temperature over 6000oCOuter core is semi-molten/liquid (only part of the planet which is!)Inner core is solidThe MantleSeparated from the core by the Gutenburg discontinuityLargely composed of silicate rocks rich in iron and magnesiumUpper mantle (close to the crust) is rigid and together with the crust forms the lithosphereMost of the mantle (asthenosphere) acts like it is semi-motlen.Temperatures near the core reach 5000oCHigh temperatures near the core are believed to be responsible for the generation of convection currents.The CrustThinnest, coolest and least dense layer.Rocks are rich in silicon, oxygen, aluminium, potassium and sodiumSeparated from the mantle by the Mohorovijic (Moho) discontinuity.Varies in thickness from 5 to 70 km

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Some very important terms:

Lithosphere: consists of the crust and the rigid upper section of the mantle, approximately 80-90km thick. Divided into seven large plates and a number of smaller ones.

Asthenosphere: the semi-molten mass below the lithosphere on which the plates float and move. Beneath the asthenosphere is the rest of the mantle, which is completely solid. 3What are the names for the two types of crust that form the lithosphere?Use the text book to complete your own table like this one:

Continental crustOceanic crustThickness

Age

Density

Composition

4Plate Tectonics TheoryKey questions:What did the Earth used to look like?Why does it look different today?How has the theory of Plate Tectonics developed?5Supercontinents!The Earth did not always look as it does today. It is believed that ~ 250 million years ago all the continents were joined together to form one supercontinent called Pangaea. Pangaea was a roughly C shaped landmass that spread across the equator.

Alfred Wegener put forward this theory in 1912.6Compare...

7Evidence for Pangaea:1: Continental fit What else?Use your text book to find out about the other evidence that supports the existence of Pangaea.2. Geological evidence 3. Climatological evidence 4. Biological evidence 8Geological evidenceThe Appalachian Mountains of eastern North America are thought to link to the Caledonidesof Ireland, Britain, Greenland, and Scandinavia and the Anti-Atlas Range in Morroco.

9Climatological evidenceCoal deposits that would have been formed in tropical climate conditions are found in places that do not have a tropical climate. Therefore, they must have drifted. E.g. Antarctica

Coal deposits that would have been formed in tropical climate conditions are found in no longer tropical climate zones they must have drifted.10Biological evidenceMesosaurusremains were found in southern Africa and eastern South America, two far away places. Mesosauruswas a freshwater animal, and could not have crossed theAtlantic Ocean, this indicates that the two continents used to be joined together.Marsupials are only found in Australia because it drifted away from the main supercontinent before the predators that wiped them out elsewhere had migrated there

Mesosaurusremains were found in southern Africa and eastern South America, two far away places. As Mesosauruswas a freshwater animal, and therefore could not have crossed theAtlantic Ocean, this distribution indicated that the two continents used to be joined together.

11So far:Wegener had convincing evidence for continental drift.However, sceptics were quick to point out that there was no explanation of the mechanism by which continents could move over a solid earth.It was not until the second half of the 20th century that major discoveries began to suggest how this might be possible.

Quite complicated...explain to class then give them sheet to make notes on?121948 A survey of the floor of the Atlantic Ocean revealed a continuous ridge running north to south. 1000km wide.Heights of 2.5kmComposed of volcanic rocks.Similar found in Pacific Ocean.

13Iron particles in lava erupted on the ocean floor are aligned with the Earths magnetic field.As the lavas solidify, these particles provide a permanent record of the Earths polarity at the time of the eruption - called palaeomagnetism.

Each magnetic particle will have its own polarity i.e its own north and south pole, and will align14Geomagnetic Polarity Reversals

However, the Earths polarity reverses at regular intervals [approx every 400,000 years]. The result is a series of magnetic stripes with rocks aligned alternately towards the north and south poles.

15i.e if all rocks were formed at same time they wouldnt have this pattern of striping, therefore the rocks have been formed over time.The striped pattern (which is mirrored exactly on either side of a mid-oceanic ridge) suggests that the ocean crust is slowly spreading away from this boundary and new rocks are being added equally on either side.

This process is known as sea floor spreading.i.e if all rocks were formed at same time they wouldnt have this pattern of striping, theyd all be aligned the same way, therefore the rocks have been formed over time.

16More evidence The age of the ocean floor.Surveys recorded very young ages for places on or near the ridges.E.g Iceland less than 1 million years old.Much older ages were recorded for ocean floor rocks nearer the continental masses (200 million years).Older crust is continuously being pushed aside by new crust.

YoungOldOld17BUT!There is no evidence for the planet growing in size as all of this ocean crust accumulates.So, what happens to all of this oceanic crust?This realisation led to the discovery of huge trenches where large areas of the ocean floor were being subducted.18Oceanic crust is being created in some areas and destroyed in others.The less dense, more buoyant continental crust is not consumed.

19One more very important thing...Convection currents:1. Higher temperatures at the Earths core and heat from the mantle help to create convection currents.2. These are zones of hotter, more liquid magma.3. Thought to have a continuous circulatory motion in the asthenosphere that causes the plates to move.

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The Driving Mechanism for Plate MovementPull crust apart at spreading ridges.Pull slabs of oceanic crust back down into the mantle at suduction zones.21Summary...1912 Alfred Wegener put forward a range of evidence for the existence of Pangaea the supercontinent.Later 20thC major discoveries:Mid-Altantic Ridge palaeomagnetism, sea floor spreading.Subduction and ocean trenches.Convection currents the cause of plate movement.

22There are three main types of plate boundary.

CONSTRUCTIVE /Divergent boundaries -- where new crust is generated as the plates pull away from each other.

DESTRUCTIVE /Convergent boundaries -- where crust is destroyed as one plate moves under another.

CONSERVATIVE /Transform boundaries -- where crust is neither produced nor destroyed as the plates slide horizontally past each other.

23Constructive marginsWhere plates move apart in oceanic areas they produce mid-ocean ridges.Where they move apart in continental crust they produce rift valleys.The space between the diverging plates is filled with basaltic lava upwelling from below.Constructive margins are some of the youngest parts of the Earths surface, where new crust is continuously being created.24Oceanic ridgesThe longest continuous uplifted features on the surface of the planet.Have a total length of 60,000km.In some parts they rise 3,000m above the ocean floor.Where two plates pull apart there is a weaker zone in the crust and an increase in heat near the surface. The hotter, expanded crust forms a ridge.Volcanic activity occurs along the ridge.25If these eruptions persist, volcanoes may develop until they reach the surface; islands can be formed in this way. Iceland is the largest example, on the Mid-Atlantic Ridge.

Surtsey: created by eruptions in 196326These volcanoes have fairly gentle sides because of the low viscosity of basaltic lava.(It can flow a long way before it cools)Eruptions are frequent but relatively gentle.

Higher viscosity = thicker, Viscosity a measure of a fluids resistance to flow. Thin= flow further before cooling.27As new crust forms and spreads, transform faults occur at right angle to the plate margin.The parts of the spreading plates on either side of these transform faults may be moving at different rates, leading to friction and ultimately to earthquakes.These tend to be shallow-focus earthquakes, originating near the surface.

28Rift valleysOccur at constructive margins in continental areas.The heating and updoming of the crust leads to fracturing and rifting.As the sides of the rift move apart, central sections drop down to form rift valleys.

29SPREADING CENTER EARTHQUAKESRIFT VALLEYS

East African Rift runs into Red Sea and Gulf of Aden.In plate tectonic theory the East African Rift is a spreading center which connectsthrough a triple junction with thespreading centers in the Gulf of Aden and the Red Sea.

It is a zone of extension and the earthquakes are created by highangle normal faults like at a mid-ocean spreading center.

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Inward facing scarpsStep faultsFracture31Volcanic activity.Active volcanoes are surface evidence of volcanic activity beneath the rift valley.

Mount Kilimanjaro

Mount Kenya32The rift valley might widen still further, allowing the sea to inundate it, possibly cutting off part of East Africa.

33The largest of these is the Great East African Rift Valley.4,000m long (from Mozambique to the Red Sea)From the Red Sea it extends north into Jordan, a total distance of 5,500km.50km wide In some areas, the inward-facing scarps are 600m above the valley floor and often marked by a series of parallel step faults.34Destructive margins.There are two types of plate, so there are three types of destructive/convergent margin:Oceanic plate moves towards continental plate.Oceanic plate moves towards oceanic plate.Continental plate moves towards continental plate.

35Oceanic-continental convergence.The denser oceanic plate is forced under the lighter continental one, into the upper mantle.This process is known as subduction.As the oceanic crust descends, friction with the overlying continental crust builds up and causes major earthquakes.

Destructive margins are some of the most seismically active zones in the world, with shallow- to deep- focus earthquakes charting the descent of subducted crust into the mantle.36

Benioff zone the further the rock descends, the hotter the surroundings become. This, together with the heat generated from friction, begins to melt oceanic plate into the magma.Rocks scraped off the descending plate and folding of the continental crust create young fold mountain chains on edge of the continental mass. E.g the Andes.Deep ocean trenches are found along the seaward edge of destructive margins. They mark where one plate begins to descend beneath another and can reach great depths. E.g. Peru-Chile trench, 8km deepAs it is less dense than the surrounding asthenosphere, the molten material begins to rise up through fissures and by burning their way through overlying rock. Eventually these reach the surface to form volcanoes.The lava has a viscous nature (flows less easily). This creates complex , composite, explosive volcanoes. If the eruptions take place off shore, a line of volcanic islands known as an island arc can appearStudents add labels to their hand out of a destructive margin. EARTHQUAKES 37Example:The Peru-Chile Trench.Also known as the Atacama Trench.Eastern edge of Nazca Plate being subducted under the South American Plate. Max depth: 8,065mLength: 5,900kmWidth: 64km

38If the eruption of magma takes place offshore, a line of volcanic islands known as an island arc can appear. Such island chains may develop over millions of years to become major land masses.E.g. Japan Pacific plate subducted beneath Eurasian plate.

Japan, 6,852 islands.39Oceanic - oceanic convergence.Two oceanic plates moving towards each other.One is forced under the other and the processes involved with subduction begin.The crust that is subducted may be marginally the denser of the two plates or is the one which is moving more quickly.

The crust that is subducted may be marginally the denser of the two plates or is the one that is moving more quickly.40Ocean trenches and island arcs are the main features, as the interaction takes place well offshore.E.g. Marianas trench western side of the Pacific Ocean.Pacific plate is being subducted beneath the smaller Philippine plate.

The deepest part of the worlds oceans. It reaches a maximum-known depth of about 11.03kilometres (6.85 mi) at the Vityaz-1 Deep[citation needed]and about 10.91kilometres (6.78 mi) at theChallenger Deep, a small slot-shaped valley in its floor, at its southern end.[1]IfMount Everest, the highest mountain on Earth at 8,848metres (29,029 ft), were set in the deepest part of the Mariana Trench, there would be 2,076metres (6,811 ft) of water left above it.[2]41GuamU.S territory, population 178,000.Where Americas day begins.

Mariana IslandsMade up by the summits of 15 volcanoes.To the west of the Mariana Trench.Guam the southern most of the islands42Continental-continental convergence.As continents have similar density and thus buoyancy, they will not be subducted.They collide with each other.Their edges and the sediments between them are forced up into fold mountains.Deep roots in the lithosphere.No volcanic activity.Movement of the plates can trigger shallow-focus earthquakes.43

Indo-Australian PlateMoving north and eastEurasian Plate (rigid)HimalayasApprox. 5.8cm/yearIn parts the Indo-Australian plate is being pushed under to form the mountain roots up to 70km deep. This movement causes great stresses which are released by earthquakes.Often extremely violent and destructive. E.g. Sichuan, 2008 China, 80,000 deaths.Causing Mt Everest to rise by up to 3cm a year.Intervening ocean, known as the Sea of Tythes, has had its sediments forced upwards. 350km wide, extend for 3,000km44

350km wide

Extend for 3,000km45Conservative margins.Occur when two plates move parallel or nearly parallel to each other. There is no creation or destruction of crust.No subduction, therefore no volcanic activity.Movement of the plates creates stresses between the plate edges. As sections of the plates rub past each other, the release of friction triggers shallow-focus earthquakes.46The San Andreas Fault.CaliforniaAlthough both plates are moving north-west, the Pacific plate moves faster, giving the illusion that they are moving in opposite directions.Los Angeles could eventually be on an island off the Canadian coast.

The Pacific plate moves about 6cm a year, but sometimes it sticks (like a machine without oil) until pressure builds up enabling it to jerk forward.47San Francisco

1906

1989Another big one predicted before 2032!!48TaskComplete the summary table of the different types of plate margin.

49Plenary

Mark Scheme

Section 2: Vulcanicity Volcanic Activity Major forms of Extrusive activityMinor forms of Extrusive activityCase study MEDC Case study LEDC52

Hot Spot VolcanismThese isolated areas of volcanic activity are not associated with plate boundariesThese volcanoes are found both on continents and out in the oceanA plume of hot mantle material rises up to the bottom of the lithosphere Melting occurs and magma is createdThese are called hot spotsThey can last for many millions of years 53

Hot Spot VolcanismThe magma works its way to the surface over the hot spot and a volcano is formedOut in the ocean, the volcano may or may not reach the surface and form an islandIn fact, few oceanic volcanoes reach the surface54

Hot Spot VolcanismAs the moving plate carries the volcano away from the hot spot, the volcano dies outWith time, another volcano may form This cycle may repeat many times, forming a long chain of under sea volcanoes and islands55

The Hawaiian Islands are the classic example of hot spot volcanismHot Spot Volcanism56Hot Spot VolcanismEvery island in the Hawaiian Island chain was created by volcanic eruptions that occurred as the Pacific Oceanic Plate crossed over a hot spot

57Hot Spot VolcanismIn fact, the 7 main Hawaiian Islands are just the southern most portion of two great undersea mountain ranges, composed of hundreds of volcanoes, that runs for 6000 kilometers (4000 miles) across the floor of the Pacific Ocean

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Hot Spot VolcanismThe plate has moved to the northwest for more than 65 million yearsThe big island of Hawaii is now over the hot spot59The volcanoes that formed the Hawaiian islands are classified as shield volcanoesHot Spot Volcanism

60Hot Spot VolcanismShield volcanoes are characterized by broad, gentle slopes built up from repeated basaltic lava flows

61Hot Spot VolcanismNot all eruption create big islandsMolokini represents one eruption that is slowly being reclaimed by the sea

62Hot Spot VolcanismLoihi Volcano, the youngest volcano of the Hawaiian Island Chain, lies about 20 km off the south coast of the Big IslandCurrently it rises 3500 meters above the surrounding sea floor and its summit is about 1000 meters beneath the surface

63An example of a hotspot: HawaiiDescribe the location of the Hawaiian Island chain in relation to plate boundaries. (you can use a simple sketch map)

What is a hotspot? Draw a simple labelled diagram to explain how a hotspot is caused and how it is responsible for forming the Hawaiian Island chain.

Why did hotspot volcanoes cause a problem when the original theory of plate tectonics was developed?

Outline the stages these hotspot volcanoes go through from birth to eventual demise.

Fold Mountain formation Task:Draw the fold mountains and ocean trenches onto your world map. Use pg 4 to help you label specific plates. Challenge:If you finish see if you can label the plate boundaries which help create each set of fold mountains you will need to use your plate boundary map. LO: To understand how fold mountains form with reference to examples.15/06/2015

Animation of fold mountainsTasks:Read the sheetAnswer the questions/diagrams and fill in the definitions. LO: To understand how fold mountains form with reference to examples.Key wordsNappes - a large, sliver of rock that has been thrusted far from its original position by thrust faulting during continental plate collisions.Anticlines - an upwardly curving fold.Synclines - A fold in rocks in which the rock layers dip downward. Geosynclines - a large-scale depression in the earth's crust containing very thick deposits.15/06/2015LO: To understand how fold mountains form with reference to examples.Sedimentary rocks are types of rock that are formed by the deposition of material at the Earth's surface and within bodies of waterOverfolds - when one or a stack of originally flat, level surfaces, such as sedimentary rock, are bent or curved as a result of pressure.Ocean trench - a long narrow steep-sided depression in the earth's oceanic crust, usually lying above a subduction zone

15/06/2015LO: To understand how fold mountains form with reference to examples.TASK- Write an extended paragraph explaining how fold mountains form over time.

Success CriteriaUse geographical vocabulary accurately.Every step of the way define each of the key terms below.Describe what happens at each stage and then give reasons why.

Fold mountains, geosyncline, sedimentary rock, syncline, anticline.

To understand the formation of ocean ridges and associated hazards.

Independent research taskProduce a case study about the Mid Atlantic Ridge. Include information about the type of plate boundary involved and how it was formed.

Further to your research, include information about Iceland, more specifically the formation of Surtsey.

Classification of volcanoes WALT: To be able to classify a volcano according to the shape, vent and nature of eruption.

1.

Fissure volcano- Occur where an elongated crack in the crust allows lava to spill out over a large area, forming lava plateau.Typically found along spreading ridges.

Rock type: BasalticLocation: rifts/early constructive marginsEruptions: Gentle, persistant.

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http://www.bbc.co.uk/news/world-us-canada-12662036752.

Shield volcano Made of basaltic rock. Form gently sloping cones from layers of less viscous lava.

Rock type: BasalticLocation: hot spots and where oceanic crust meets oceanic crust.Eruptions: Gentle, predictable.

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Shield Volcano Lava cone77

Mauna Loa, Hawaii the largest volcano in the world. Stands at 4,170m above sea level.Extends 10,099m from the ocean floor, making it taller than Mount Everest.

783.

Composite volcanoThe most common type found on land. Created by layers of ash from initial explosive phases of eruptions and later layers of lava from the main eruption phases.

Rock type: Andesitic is of moderate viscosity and forms thick lava flows and domesLocation: Destructive marginsEruptions: Explosive, unpredictable

79Mount St Helens, USA

804.

Acid or dome volcano Steep-sided Formed from very viscous lava Lava cannot travel far It builds up convex cone-shaped volcanoes

Rock type: Rhyolitic - Rhyolitic lava has the highest viscosity of any type of lava, and it has the greatest content of SiO2. Typically, the SiO2 content is greater than 68 percent of its total composition. It flows much slower than andesitic and basaltic lava. Location: Continental crustEruptions: Explosive, unpredictable

Puy de Dome, France815.

Ash-cinder cone volcano Slightly concave sides Layers of fine ash and large cinders

Rock type: MixedLocation: VarietyEruptions: Explosive

Northern Arizona826.

Caldera volcano Form when gases that have built up beneath a blocked volcanic vent result in a catastrophic eruption that destroys the volcano summit.

Rock type: AndesiticLocation: Destructive marginsEruptions: Very explosive, unpredictable

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Geyser

SolfataraHot springs/boiling mudCreated when sulphurous gases escape onto the surface.Hot water mixes with mud and surface deposits.Water in the lower crust is heated by rocks and turns to steam; pressure increases and the steam and water explode onto the surface.Minor Volcanic forms85Shape of VolcanoDiagramRock typeLocationType of eruptionFissure VolcanoShield VolcanoComposite VolcanoAcid or dome volcanoAsh-cinder cone volcanoCaldera volcano

LavaThe physical nature of lava is linked to its chemical composition

88Lava

89General rules

90Basaltic Lava

A

Phoehoe91Flood Basalts (lava plateaux)Form from fissure eruptionsFlow over great distances

Snake River Plain USA92Acid Lava

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94Intrusive VolcanismSill

Dyke

Batholith95PlutonsLarge masses of intrusive igneous rock. Most commonly granite.Plutons and batholiths are often used interchangeably.

96Sierra Nevada Batholith (red).

97LaccolithFormed when an igneous intrusion goes in between layers of rock and bubbles up.

98Dike and Sill

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Geysers are hot springs that erupt periodically. Water in the lower crust is heated by rocks and turns into steam; pressure increases and the steam and water explode onto the surface.The ingredients needed for geyser activity are: heat, water, and underground rock hard enough to withstand intense pressures. Extrusive FeaturesA hot spring is a spring that is produced by the emergence of geothermally heated groundwater from the Earth's crust. There are hot springs all over the earth, on every continent and even under the oceans and seas.Other features

Lassen Volcanic Park

mudpot Boiling mud: hot water mixes with mud and surface deposits.A fumarole is an opening in Earth's crust, often in the neighborhood of volcanoes, which emits steam and gases such as carbon dioxide, sulfur dioxide, hydrochloric acid, and hydrogen sulfide.

The name solfatara is given to fumaroles that emit sulfurous gases.

Fumaroles may occur along tiny cracks or long fissures, in chaotic clusters or fields, and on the surfaces of lava flows and thick deposits of pyroclastic flows. A fumarole field is an area of thermal springs and gas vents where magma or hot igneous rocks at shallow depth are releasing gases or interacting with groundwater. From the perspective of groundwater, fumaroles could be described as a hot spring that boils off all its water before the water reaches the surface.

Hverarnd sulphuric mud pools (solfataras). The ground is unstable there and you cannot walk everywhere. Blue-gray mud is boiling and produces small or big (depending on water content) bubbles that burst. The ground is yellow and reddish and the noise from an abandoned hot water well is penetrating. The smell of sulphuric dioxide is everywhere. EYJAFJALLAJKULLTo understand:

the nature of the volcanic hazardthe impact of the eventmanagement of the hazard and responses to theevent.

As the eruption took place beneath glacial ice, the resulting melt water flowed back into the erupting volcano which created two specific phenomena:The first response was that 500 farmers were evacuated overnight. Some roads were closed for fear of flash floods

Between 14th and 21st April flights in the airspace of many NW European countries were stopped.The 6 day shut down is estimated to have cost the airlines 1.2bnThe Kenyan flower industry was also impacted by the eruption, costing growers between $1.5m and $2m a day. A royal Navy warship collected soldiers returning from Afghanistan and stranded holiday makers from the Spanish port of Santander.Vaporizing water increased the explosive power.The lava cooled very rapidly creating a cloud of highly abrasive, glass rich ash which could damage jet engines.

The volcano was located directly under the polar jet stream which was heading NW to SE.

A thick layer of ash fell on farm pastures at Raufarfell. This has become wet and compact, making it very difficult to continue farming, harvesting or grazing livestock.

There was some reports of dangers to livestock in the local area and even as far as Scotland due to ingestion by livestock of fluoride from volcanic ash on pasture land.Eyjafjallajkull is one of Icelands smaller icecaps located in the far south of the island. It covers the caldera of a volcano 1666m in height.The volcanic events started in March 2010 are considered to be a single eruption divided into different phases.Initially a fissure opened up, about 150m in length with 10 to 12 erupting lava craters ejecting lava at a temperature of about 1000c up to 150m into the air.This eruption produced a spectacular volcanic Disneyland and tourists flocked to the site to see amazing lava flows. The lava was basalt and relatively viscous so lava flow was slow.

12th April.A second volcanic fissure opened during an earthquake measuring 3.2 magnitude beneath Eyjafjallajkull and many smaller earthquakes were recorded

1.15am 14th April.Eyjafjallajkull entered an explosive phase and ejected fine, glass-rich ash to over 8km into the atmosphere over 4 days. Lava flowed up to 3 km from the main vent.

The second phases is estimated to have been a volcanic explosive index (VEI) 4 eruption, which is large, but not nearly the most powerful eruption in VEI termsThe volcano is in a remote corner of Iceland. The local, dispersed farming community is home to few people. River levels rose as part of the ice cap melted this disrupted roads and damaged bridges in places. Some local gravel roads were also blocked by falling ashWhat made this volcanic eruption so hazardous was the fact that the ash became disruptive to air travel.

Type of volcano=Cause =Type of eruption=

Lava type=

VEI =

Impacts

What made the volcanic activity worse?

Responses

Case study: Nyiragongo

To be able to compare and contrast two case studies of major volcanic events.

2 mile high volcanoOne of the most active volcanoes on the planet

Little research20 years of constant WarfareMass migration from Rwanda20,000 UN troops111Traders ferry logs and charcoal 12 miles form the forests around Ny to Goma which continues to swell with refugees fleeing the war-torn east.

Goma 10 Miles [16K]Population 1 million2 lava flows through city 1977 + 2002

1977

60 mph

Several hundreds killed2002

14,000 homes

350,000 flee

15 million cubic yards of lava

Houses buried to the first floor

The PlayersDario TedescoItalianEU funded

Goma, is the most dangerous city in the world.

My greatest fear is to make a big mistake not to predict and eruption.Ken SimsUS vulcanologistUniversity of Wyoming

Rock Climber and mountaineer

Hasnt owned a TV set for 25 years

Fissure type eruptions not the classic Plinian type

Lake 700 feet across

1800o F

Lava geysers up to 100ft

Expedition to crater lake led by Sims + TedescoCampsite on TerraceLowered to cater lake to collect zero-age sample

Every day 7000 tones of Sulphur DioxideGas sniffer tests carbon dioxidecarbon monoxide + methaneRAD7 testsFor RadonWhy?

Volcanoes are gas driven machinesEruption preceded by:Increase discharged gasVariations chemical composition

Two isotopes of radon measured by radioactive clock ratio indicates time to surface and chemical composition can be extrapolated.

Prediction piecemeal so scientists visits essentialVolcanic observatory dilapidated one story building in GomaWarning flags bleached and batteredBatteries from sensors looted

Meanwhile the zero-age sample from the crater lake could be the Rosetta StoneSection 3 : Seismicity Earthquake Activity TsunamisCase study MEDC Case study LEDC123

WHAT IS AN EARTHQUAKE?Sudden release of energy

Creates seismic waves (similar to waves through water)

Waves spread out spherically

Greatest damage occurs at the epicentre124P-wavesP waves (primary waves) are compressional waves. In solids, these waves generally travel almost twice as fast as S waves.P waves can travel through any type of material. In air, these pressure waves take the form of sound waves.They travel at are 330m/s in air, 1450m/s in water and about 5000m/s in granite. (m/s = meters per second.)

PRIMARY WAVE p-waveLongitudinalSudden jolt felt as the quake hits.126126S wavesS waves (secondary waves) are transverse which means that the ground is displaced perpendicularly (sideways) to the direction of movement. The ground moves alternately to one side and then the other. (or up or down depending on the direction of the wave.)S waves can travel only through solids, not fluids (liquids and gases) Their speed is about 60% of that of P waves in a given material. S waves arrive second in a seismic station because of their slower speed. They are sometimes called shear waves.

SECONDARY WAVE s-waveTransverse (shake at right angles to the direction of the wave.)Sustained shaking felt as quake hits

128128L waveThe particle motion of a Love wave forms a horizontal line perpendicular to the direction of movement (i.e. are transverse waves). Since Love waves travel on the Earth's surface, the strength (or amplitude) of the waves decrease exponentially with the depth of an earthquake.Surface waves therefore decay more slowly with distance than do secondary waves, which travel in three dimensions.Large earthquakes may generate Love waves that travel around the Earth several times before dissipating.Since they decay so slowly, Love waves are the most destructive outside the immediate area of the focus or epicentre of an earthquake. They are what most people feel directly during an earthquake.

LOVE WAVE. L-wave

Lets get an overview.Read the book pages 24 - 27Worksheet Sheet 5 & 6

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What is an earthquake?

FocusEpicentreShock waves133How do we measure earthquakes?

Seismograph134

The Richter Scale- Is used to measure the strength of an earthquake.135

136

137

The Mercalli Scale measures the effects of an earthquake using a scale of I to XII

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Distribution of EarthquakesWhat is the distribution of Earthquakes?Read the section in the book then use following statements to make a short paragraph explaining the distribution of Earthquakes.The Pacific Ring of Fire70% of Earthquake and Volcanic activity is found around its edgesVolcanoes and Earthquakes are frequent.Represents the destructive plate boundaries around the edges of the plate.139

Describe the distribution and comment on the relative impact of these earthquakes. (7)

THE RICHTER SCALEInvented by Charles Francis Richter in 1935

Measure of an earthquakes magnitude

Scale between 0 and 10(theoretically)

Logarithmic scale

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Liquefaction Explained

When violently shaken, soils with high moisture content lose their mechanical strength. Moisture is shaken to the top layers of soil, even those that seem extremely dry, and begins to behave like liquid. Causing buildings to become unstable on their foundations, sink and or collapse.http://www.youtube.com/watch?v=PwvvYxSZ7PIhttp://www.youtube.com/watch?v=sV2WeR670ls

142Tsunami -What is a Tsunami?Tsunami -a large wave, or series of waves, caused when an earthquake causes massive undersea crust movements and/or collapses which displace the water above.Earthquakes deform the ocean floor, pushing the overlying water up into a tsunami wave. Video of Boxing Day TsunamiTsunami Caught on Camera

Scale showing the size of the tsunami waves that hit Indonesia.

Case study Boxing Day Tsunami.Make a 5 point PowerPoint to get the key facts about the Tsunami across. Use case study on page 29 to help.Why it occurred.Where it started.What it effected.Positive side effects.

Case study: Japan TsunamiCase study: HaitiWhat was the response?

[numbers refer to pages]

[numbers refer to pagesHistorical influencePiracy and conquests True governmentDictatorshipCoup and US intervention Import and exportsSee associated Historical notes

Geography Mountains and plainsReliance on primary produceCentralisationMigrationCurtailed secondary industryRim of mountain concentrated on narrow coastal plain. Centralised location encouraged by historical growth, garment prodution seen as only growth pole. [see as potential second Taiwan by US]

The eventEpicentreMagnitudeConstructionOrganisation Out of PaP but close and shallow relief concentrated in city. Primary - emergency ReliefWaterFoodSearch and Rescue Shelter tarps and tentsRiots and security Concentration at the core Logne? NGO met behind secure wall afraid of engaging with local and riots which never came Worst hit areas unserved

Primary response - POSITIVESMedical - thousands of life saving and emergency amputations50% more water treated 107 flights a day c.f. 7Vaccinations against measles, tetanus + diphtheria Mid term - RecoveryLand ownershipAid and DebtCorruption 130 Bilateral aid (NGOs)Land ownership real sticking point title deeds lost in damage. Would not give aid to govt. for fear of corruption but NGOs did ot spent it or receive full debt

Collier Plan 139Garments Agriculture reconstruction Informal industry but no reliability, sufficient income or security March 31 2010 led conference as Special envoy No locals spoke (secondhand 7 min presentation) 146Emphasis on private moneyPages in book way forward through private investment Mid term evacuationPrior to first summit land seized by government 9 miles out of city - Corail Cesselesse Ownership was undeclaredUS flattened a site and tents for 7500 were put up, latrines dugPlan originally for 50000 who would be flooded come springEventual realisation land owned by Brun and Nabatec who wanted to develop garment factory for S Korea on remainder and would benefit from labourGrowth pole attracted informal squatter so was never built moving to Caracol in far North. Suggestion that land deal to secure labour base for S Korean investment was set up eventually tax free in the north. Progress?7 months after quake, four after donors conference and two after Interim Haiti Recovery Commission2% rubble cleared, 13,000 temporary shelter built out of 125,000 promised 203 Bill Clinton special envoys office suggested $16.3B spent or promised. By end of 2010 $2.43B spent by UN or NGOs but 93% went straight back to UN or NGOs to pay for supplies or personnel! Copy pages 202-203 + 204-205 to get all figures.

October 17 2010First death from cholera in Meille on the Artibonite riverBy 30th October death toll had passed 400Broken latrine pipes and sewage dumped in open pits on the riverside discharged human effluent . UN camp at Minustah recently has new soldiers from Nepal a known source region for Vibrio Cholera bacteria. 241,26 November - first case reaches PaP Mid November 1000 dead, Dec 4000By Jan 2013 7500 dead, 580k ill (6%) epidemic spreading to Dominican RepPort-au-Prince, Haiti

Earthquakes dont kill people BUILDINGS DO!!!157157ElectionFirst round of election in December 2010 supported Celestin, the Unity candidate who Preval saw as his successorPotential winner Martelly (musician) with support of the youthful population failed to qualify, leading to extended riotsOrganisation of American States recounted suggesting - no recount (due to cost - removal of fraudulent tally sheetsMartelly would go through Celestin not.LeadershipFollowing intervention and visit of Hilary Clinton election continued fairly with two horse raceMartelly secures 67.5 % of vote and enters new phaseDuvalier and Aristide return, both shadows of former self and Preval fades into background. Overall IssuesPrior to the event political and natural background had led to the poorest country in Western WorldPost quake fears of violence led to poor interaction with locals limiting distribution of food.NGOs concentrated in capital [at hotels and previously known locations]Aid was sourced inefficiently through NGOs and UN as government perceived to be corruptDisorganised land ownership made the establishment of T-shelters difficult meaning permanent housing was never establishedCholera outbreak dealt a double blow before any real changesSynthesis by MOHOW TO BUILDSMALL BUILDINGSShear walls

Concentrate the damage

Cross BracingReinforced stone wall

161161Cross bracing Construction of Pearl River Tower, China

162162LARGER BUILDINGSBase isolation

Left: regular building Right: base isolated building

163163Ways of improving resistance to earthquakes

164164SKY SCRAPERSTuned Mass Damper

The tuned mass damper at the top of the Taipei 101

165165HAITIA poor neighbourhood, Port-au-Prince

166166CHILE Damaged building, Concepcion

167167

http://ngm.nationalgeographic.com/big-idea/10/earthquakesSafe HousesThe earthquake in Haiti was a reminder: Billions of people live in houses that can't stand shaking. Yet safer ones can be built cheaplyusing straw, adobe, old tiresby applying a few general principles.

http://ngm.nationalgeographic.com/big-idea/10/earthquakes-pg2Appropriate?In Los Angeles, Tokyo, and other rich cities in fault zones, the added expense of making buildings earthquake resistant has become a fact of life. Concrete walls are reinforced with steel, for instance, and a few buildings even rest on elaborate shock absorbers. Strict building codes were credited with saving thousands of lives when a magnitude 8.8 quake hit Chile in late February. But in less developed countries like Haiti, where a powerful quake in January killed some 222,500 people and left more than a million homeless, conventional earthquake engineering is often unaffordable. The devastation in Haiti wouldnt happen in a developed country, says engineer Marcial Blondet of the Catholic University of Peru, in Lima. Yet it needn't happen anywhere. Cheap solutions exist.

Reinforced WallsEucalyptus and Bamboo structures help to strengthen

Plastic meshes are effective too

Need not be a metal meshBlondetBlondet has been working on ideas since 1970, when an earthquake in Peru killed 70,000 or more, many of whom died when their houses crumbled around them. Heavy, brittle walls of traditional adobecheap, sun-dried brickcracked instantly when the ground started bucking. Subsequent shakes brought roofs thundering down. Blondet's research team has found that existing adobe walls can be reinforced with a strong plastic mesh installed under plaster; in a quake, those walls crack but don't collapse, allowing occupants to escape. "You rebuild your house, but you don't bury anyone, Blondet says. Plastic mesh could also work as a reinforcement for concrete walls in Haiti and elsewhere.

Confined MasonryBrick wall framed within concrete uprights corner column

And fixed horizontal beams crowns

The box flexes on cheap ground absorbers made from tyresLindtOther engineers are working on methods that use local materials. Researchers in India have successfully tested a concrete house reinforced with bamboo. A model house for Indonesia rests on ground-motion dampers designed by John van de Lindt of Colorado State University: old tires filled with bags of sand. Such a house might be only a third as strong as one built on more sophisticated shock absorbers, but it would also cost much lessand so be more likely to get built in Indonesia. "As an engineer you ask, What level of safety do I need? van de Lindt says. Then you look at whats actually available and find the solution somewhere in between."

Light walls and gablesLighter buildings subject to smaller forces

Compressed straw bales held together with nylon netting

Within plaster sandwich DonovanIn northern Pakistan, straw is available. Traditional houses are built of stone and mud, but straw is far more resilient, says California engineer Darcey Donovan, and warmer in winter to boot. Donovan and her colleagues started building straw-bale houses in Pakistan after the 2005 earthquake; so far they have completed 17.

Small windowsLight Roofs Concrete roofs collapse killing, metal roofs and wooden trusses are lighter

Smaller, regularly spaced opening cause less stresses

In Haiti improperly re-enforced walls collapsed along with heavy roofs