LA 4 - Suggested Answers.pdf

Name : _________________________ ( ) Class : Year 2 / ________ Date : __________ Suggested Answers Theme : The World as Interacting Systems...

Name : _________________________ ( ) Class : Year 2 / ________ Date : __________ Suggested Answers Theme : The World as Interacting Systems LA 4 Topic : Natural Disasters: Volcanic Eruptions 1. Compare the effects/impacts of the volcanic eruptions of Soufriere Hills Volcano, Montserrat and Mt St Helens, USA based on the web sources provided. Use the following links on the web to get your resources. Soufriere Hills Volcanic eruption: Raffles Girls’ School http://www.bbc.co.uk/scotland/education/int/geog/envhaz/flash/volcanoes/index.shtml http://www.volcanodiscovery.com/montserrat.html Raffles Progra Geography For Glob Year Two 20 Mt St Helens Volcanic eruption: http://www.livescience.com/27553-mount-st-helens-eruption.html http://www.rgs.org/NR/rdonlyres/C62A6824-C12E-4D6C-A879- 14ED8240CA04/0/CGT_NetRaising_8StHelensessay.pdf Soufriere Hills Volcano, Mt St Helens, USA (1980) Montserrat (1997) Background Information Background Information Level of development of country: Level of development of country: High Low SIMILARITIES Both are composite/stratovolcano volcanoes which led to violent eruptions. Both eruptions resulted in pyroclastic flow (hot rocks and gases) and lahars Both volcanoes are found along destructive plate boundaries (Mt St Helens between North American plate and Juan de Fuca plate; Soufriere Hills between the Atlantic plate and the Caribbean plate).  DIFFERENCES Pyroclastic flows and surges P The mountain exploded - destroyed and flattened h Effect on the natural sideways, sending a colossal thousands of trees y landscape landslide downslope. s Volcanic ash and rock deposits i St. Helen’s summit elevation was - covered a total of at least 4 c approximately 2,950 m and after, square kilometres of land a declined to about 2,600 m. l Note: A super-heated pyroclastic flow - Pyroclastic flows are ploughed down the mountainside, extremely fast-moving flows levelling millions of trees. of lava, hot rocks and gas that flow down the side of A pillar of ash and gas rose high the volcano into the sky, blocking the sun and - Pyroclastic surges are fast- turning daylight into darkness. moving clouds of hot ash that travel with the pyroclastic flow. - During the eruption, between 4 – 5 million cubic metres of lava was unloaded in the form of pyroclastic flows and surges. Houses were buried or burned E Damage/Destruction The enormous landslide and by the intense heat of the c of property and pyroclastic flow destroyed more pyroclastic flow and surges. o physical hundreds of homes, buildings n infrastructure and infrastructures such as road Many villages were affected by o and railways. ash deposits such as the m villages of Farms and Trant’s i The lahars of St. Helens flowed were completely buried by ash c into the Toutle and Cowlitz rivers, deposits. travelling many miles down the two, extensively damaging Other houses in the Exclusion around 35 bridges in the process. Zone were destroyed by direct Monetary/ Financial 3 million m3 of material was impact of rocks up to 5 metres Loss transported 17 miles (27 km) into in size. the Columbia River by these mudflows. The capital city, Plymouth was gradually being buried by lahars Several airports had to be shut (rapidly moving river of ash and down also, and over 1,000 flights water which buried properties, were cancelled because of ash vegetation and crops) and accumulation and poor visibility, destroyed (It was directly in the Effect on causing unsettlement for staff path of the main pyroclastic Employment and people awaiting flights. flow) The economic cost of the The closure of the island’s eruption was estimated at airport halted much economic US$860 million. activity Officials closed highways for a Decline in the economy of week, and airlines cancelled Montserrat as tourist arrival more than 1,000 flights. dropped. Inevitably, unemployment around Destruction of properties, St. Helens immediately followed factories and farms negatively the eruption but was back to affected the livelihood of the nearly normal once the timber people. salvaging and ash clean-up operations were underway. Only an incredibly small percentage of residents left the region because of lost jobs due to the event.  S Residents’ An immediate response to the o Attitude/Perception eruption was evacuation. c i Emotionally attached with some 19 people were killed by the a Death Toll refused to leave. pyroclastic floes and surges in l the Exclusion Zone. (They had ventured back into the high-risk The eruption killed 57 people, in areas for different reasons) the lateral blast, ashfall, and lahars Seven people were killed by the Extent of Injury surge in the Streatham and Windy Hill area. Six of the victims were found outside houses, they had been attempting to seek shelter. Two other bodies were recovered Extent of Emotional Some people living near the from the pyroclastic flow Trauma eruption suffered from post- deposits near Trant's. Most of traumatic stress syndrome: the remaining missing persons depression, troubled sleep, are thought to have been in the irritability, and a sense of village of Farm, which was powerlessness. buried by deposits several metres thick, and were never Effects of recovered. Relocation Other survivors suffered burns to various parts of their bodies, including inhalation injuries and burns to the nostrils and mouth. Half the island’s population was displaced. VOLCANOES “Hiking on a Saturday morning at Mt. Ontake, Japan” HTTPS://YOUTU.BE/AQTKOLXQUNQ ESSENTIAL QUESTIONS EQ 3: Is living in tectonically-active areas necessarily detrimental to one’s well-being? (P) ENDURING UNDERSTANDINGS EU 2: An understanding of the tectonic forces can enable humans to harness Earth’s resources and respond to its disasters in order to benefit society. EU 3: The level of preparedness of a country can determine the severity of damage caused by tectonic activities in order to improve its capacity to respond and manage the tectonic disasters. I LAVA YOU I Lava You (Hawaii) (Pixar): https://www.youtube.com/watch?v=uh4dTLJ9q9o Where is this taking place? Why did the volcano ”shrink” over the years?  Which parts are factual / fictional? https://oncirculation.wordpress.com/2015/10/15/disney- pixars-lava-explained-by-a-geologist-volcanologist/ VOLCANOES – AN INTRODUCTION Volcanoes 101, National Geographic https://www.youtube.com/watch?v=VNGUdObDoLk DISTRIBUTION OF VOLCANOES IN THE WORLD Source: https://qph.ec.quoracdn.net/main-qimg-05d70406ebc1b106035fa4a5b681defe DISTRIBUTION OF VOLCANOES IN THE WORLD MAJOR VOLCANOES IN THE WORLD DISTRIBUTION IN RELATION TO PLATE BOUNDARIES Along convergent plate boundary where subduction takes place Produce chain of volcanic islands e.g., Pacific Ring of Fire Along divergent plate boundary where new sea floor materials produce submarine volcanoes e.g., Mid-Atlantic oceanic ridge Away from plate boundary, a plate moving over fixed ‘hot spots’ Which are localised heat sources in the mantle to produce groups of volcanoes e.g., the Hawaiian Islands WHAT IS A VOLCANO? A landform produced by magma emerges via an opening in the crust as lava flow Lava cools and solidifies to form a layer of volcanic material with each eruption, layer upon layer built up to form a volcano. Lava continues to rise through a passageway – pipe. Lava ejected at a top opening – crater Crater when blown off caldera Crater or caldera eventually filled with water crater lake PARTS OF A VOLCANO https://golearngeo.files.wordpress.com/2010/02/volcanostructure.jpg CLASSIFICATION OF VOLCANOES Active: erupts frequently and in recent times Dormant: not erupted for quite some time but is not considered extinct Extinct: has not erupted in historic times; solidification sealed off vent and volcanic shape may disappear TYPES OF VOLCANOES http://thebritishgeographer.weebly.com/uploads/1/1/8/1/11812015/4093514.jpg?532 “Why do volcanoes look different from each other?”  Influences shape of volcanoes BASIC LAVA VS ACID LAVA Quiet Explosive eruptions basic lava acid lava eruptions! … Acid Lava https://youtu.be/co qEmEyg95Q Basic lava https://youtu.be/K wGReC3_2C0 ACID LAVA VOLCANO MT. LASSEN, US  ACID LAVA VOLCANO Charx. of volcano Charx. of eruptions dome-shaped violent due to possibility of lava blocking vent steep may blow off top, forming caldera crater lake convex slopes Charx. of lava viscous acidic flows slowly cools & solidifies rapidly http://www.s-cool.co.uk/gifs/g-geo-plates-dia06.gif may cool and solidify along pipe COMPOSITE VOLCANO/ STRATOVOLCANO STRATOVOLCANO/ COMPOSITE VOLCANO Charx. of volcano concave (steep towards top, gentler at base) cone-shaped alternate layers of acid lava and ash+cinder Charx. of lava Charx. of eruptions viscous violent acidic lava may escape flows slowly through secondary presence of ash & cones cinder Supervolcanoes: http://catevet2.weebly.com/uploads/1/7/9/7/17974811/6032583.gif?416 https://www.youtube.com/watch?v =kAlawvE8lVw STRATOVOLCANO/ COMPOSITE VOLCANO MT. PINATUBO, PHILIPPINES  Crater Lake Pyroclastic flow Mt. Pinatubo Volcanic landscape Volcanic eruption  ERUPTION , ANAK KRAKATOA, INDONESIA Night scene: https://youtu.be/NGcbNn4Vk1 w https://youtu.be/NLhjNz QHphQ  What is a pyroclastic flow? https://youtu.be/EZdFqvnzClU (0-1’28”) A pyroclastic flow (also known scientifically as a pyroclastic density current) is a fast-moving current of hot gas and volcanic matter (collectively known as tephra), which reaches speeds moving away from a volcano of up to 700 km/h (450 mph). The gases can reach temperatures of about 1,000 C (1,830 F). SHIELD VOLCANO  SHIELD VOLCANO Charx. of volcano Charx. of eruptions Charx. of lava frequent but quiet & gentle fluid broad-based eruptions basic cone-shaped explosions are less powerful flows faster than acid lava due to easier release of gases gentle slopes from basic lava cools & solidifies slowly https://www.google.com.sg/search?q=shield+volcano&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjNsOao-9nNAhXENo8KHQO6CDoQ_AUICCgB&biw=794&bih=702&dpr=2#imgdii=TQboPq4fEfsb3M%3A%3BTQboPq4fEfsb3M%3A%3B3LoQpAz wGH_ZkM%3A&imgrc=TQboPq4fEfsb3M%3A HAWAIIAN SHIELD VOLCANOES  Note the percentage of land above the waters (ENRICHMENT) FORMATION OF HAWAIIAN ISLANDS – HOT SPOT VOLCANOES “Associate the characteristics of lava with the type of eruption for shield volcanoes” VOLCANIC ERUPTION IN HAWAII: HTTPS://YOUTU.BE/1FEVV8HGKO4 (1’05”) River of Lava - https://youtu.be/21bZx0vBI9s (4’10”) A short History of volcanoes in New Zealand, a combination of convergence and hotspots HTTPS://YOUTU.BE/6UXVXQT1IL0 (2’29”) COMPARISON OF VOLCANOES *Compare shield volcanoes and stratovolcanoes *Compare = similarities and differences https://youtu.be/ImS9tqkrJV U WHAT IS VULCANICITY What is vulcanicity? Benefits vs hazards IMPACT OF VOLCANIC ERUPTION http://image.slidesharecdn.com/whatarevolcanoesandwhydotheyerupt-091117110649-phpapp02/95/what-are-volcanoes-and-why-do-they-erupt-9-728.jpg?cb=1258456032 VOLCANIC HAZARDS https://mrgeogwagg.files.wordpress.com/2015/06/volcano-hazards.png IS LIVING IN TECTONICALLY-ACTIVE AREAS NECESSARILY DETRIMENTAL TO ONE’S WELL-BEING?(EQ3) WHAT BENEFITS COULD IT BRING TO THE ENVIRONMENT AND PEOPLE? PRIMARY EFFECTS SECONDARY EFFECTS BENEFITS OF VULCANICITY formation of soil precious stones and minerals tourism geothermal energy SOCIO-ECONOMIC BENEFITS – FERTILE SOIL FOR AGRICULTURE The lava that has weathered down to form soils and ash that has settled on the ground are rich in nutrients to aid plant growth. People have a livelihood by earning an income through the sale of crops As food is grown, this provides access to food and food security Rice farming at the foot of Mt Mayon, Philippines Vineyard (grape farming to produce wine) at the foot of Mt Etna, Italy  SOCIO-ECONOMIC BENEFITS – MINING FOR RESOURCES Working as sulphur miners is employment for people to earn income Sulphur is sold for revenue. Some industrial uses of sulphur include making fertilisers, disinfectant and black gun powder (for fireworks). Sulphur Mining in the crater of Mt Ijen, Indonesia  SOCIO-ECONOMIC BENEFITS – TOURISM REVENUE The tourism industry makes use of the scenic beauty and attractions provided by the volcanic landscape, such as the volcano itself and its hot springs. People can be employed as hotel employees and tour guides, or earn a livelihood by running businesses such as cafes near these attractions. Hot springs or onsens in Japanese, are tourist attractions, where people visit to have a bath. Hot spring operators earn revenue from providing this service. Hotels are booked based on the quality of their hot springs. Taking a hike, a hot spring bath and watching the scenery of the volcanic region are recreational activities that people enjoy doing. This photo is an advertisement for a Full-Day Private Enjoying a hot spring bath with the view of Nagano Tour: Zenkoji Temple, Obuse, Jigokudani Monkey Mt Fuji, Japan Park that costs about SGD 280  SOCIO-ECONOMIC BENEFITS – GEOTHERMAL ENERGY Geothermal energy is heat within the earth. Geothermal energy is a renewable energy source because heat is continuously produced inside the earth. People use geothermal heat for bathing, to heat buildings, and to generate electricity. This generation of electricity is necessary for industrial and commercial development, as electricity is needed to drive machinery and equipment; as well as the use of electrical appliances, for heating in winter and cooling in summer in homes for domestic consumption. The Svartsengi geothermal power station near Grindavik, Iceland. Geothermal power facilities currently generate 25% of the country's total electricity production. (SOURCE: ARTERRA/UNIVERSAL IMAGES GROUP VIA GETTY IMAGES)  SOME FUNFACTS (NOT TO BE CARRIED OUT ON YOUR OWN WITHOUT SUPERVISION!) Black onsen eggs (Kuro Tamago) boiled in the hot spring waters of Owakudani, Hakone in Japan are sold to tourists. Due to the reaction with sulphur in the hot spring water, the egg shells turn black. Eating one Kuro Tamago egg is believed to prolong your life by 7 years! Scientist cooking steak over lava (Refer to the talk by EOS expert) Jigoku Mushi refers to a special type of cuisine cooked in the steam of Beppu’s hot springs (Japan), also called Beppu’s ‘hells.’ Vegetables and seafood are placed in a steamer and gradually cooked in the hot air generated by the hot springs, a Scientist cooking hot dogs over lava flow in Iceland (Refer to traditional cooking method that has the talk by EOS expert) existed in Beppu since the Edo period.  SOCIO-ECONOMIC BENEFITS – UNWILLINGNESS TO RELOCATE Based on study of people living near Mt Sinabung, Indonesia: Key factors explaining why people live in these dangerous situations are attachment to place and the protection of their livelihoods as well as a capacity to adapt to natural hazards and the reduced perception of risk that involves. https://theconversation.com/why-do-people-still-live-next-to-an-active-volcano-59947 Based on study of people living near Kilauea volcano, Mt Sinabung rumbles away in Hawaii: Jun 2015…but local farmers appear unconcerned One of the reasons is that some people simply do (Source: Dedhi Sahputra / not have the financial resources to move. EPA) https://www.nationalgeographic.com/culture/article/active-volcano-kilauea-hawaii-agung- mayon-community-culture  CULTURAL/SPIRITUAL ATTACHMENT/ROOTEDNESS Mount Merapi Javanese culture is full of mysticism and Maridjan took his job seriously. Too seriously perhaps. When officials came to tell him it was time to leave the volcano's lower slopes and move to safety, he refused. His place, he said, was at home, trying to pacify the spirits' brewing anger. When the burning clouds of ash descended, he, and many of those who had come to reason with him, were killed. http://www.bbc.com/news/world-asia-pacific-11646879 Plate Tectonics  EQ1: WHAT IS PLATE TECTONICS? EQ2: IS THE EARTH AN UNFINISHED PLANET? EU1: THE MOTION OF TECTONIC PLATES CAN CONSTANTLY CHANGE THE EARTH’S LITHOSPHERE THAT RESULTS IN A STATE OF EQUILIBRIUM  LA1: WHERE ARE VOLCANOES , OCEANIC TRENCHES AND EARTHQUAKES DISTRIBUTED IN THE WORLD? https://www.sciencephoto.com/media/167169/view/earthqu ake-distribution-map https://www.pbs.org/wgbh/nova/teachers/activities/2515_vesuvius.html THE INTERNAL STRUCTURE OF THE EARTH THE EARTH INTERNAL STRUCTURE SUMMARY OF EARTH’S INTERNAL STRUCTURE Earth’s Layers Layer Thickness Temperature (oC) Composition (km) Less dense Continental 10 - 70 minerals, such as aluminium Crust -14 to 1200 Denser minerals, such Oceanic 5 - 10 as magnesium Mantle Mixture of solid (upper mantle and 2900 1400 to 3000 and semi-molten lower mantle) rocks (magma) Outer 2100 Mostly iron and Solid 3000 - 5000 nickel, forming an Core alloy Inner 1370 DISCOVERIES AFTER CONTINENTAL DRIFT THEORY….. Magnetic Striping on the seafloor … STUDIES OF PALAEOMAGNETISM,1950s DISCOVERY OF MID-ATLANTIC RIDGE, 1948 http://www.coolgeography.co. uk/A-level/AQA/Year%2013/ Plate%20Tectonics/Plate%20t ectonics/Tectonics%20&%20 Evidence.htm SEAFLOOR SPREADING, 1962 (HARRY HESS) https://www.quora.com/Why-is-sea-floor-spreading-important  PLATE TECTONICS THEORY The Plate Tectonics theory states that the Earth is in constant motion Convection Current in the mantle drives the movement of plates. Plate movements creates major landscape and landforms such as volcanoes, fold mountains and many more. Plate movements also cause earthquakes. MOVEMENT OF TECTONIC PLATES The movement of the earth's crustal plates is believed to be due to *convection currents which occur in the mantle. Convection currents are created by heat from the earth’s core - much of which is generated by radioactive decay in the core. *solid-state convection Video 1’13”: Plate Tectonics: https://youtu.be/ryrXAGY1dmE WHAT ARE TECTONIC PLATES? LITHOSPHERE  OCEANIC CRUST, 6 - 11KM 62% SILICA LITHOSPHERE (CRUST + UPPER MANTLE) CONTINENTAL CRUST UP TO 100KM (CONTINENTS + SHALLOW SEAFLOOR) 25-90KM 49% SILICA ASTHENOSPHERE PLATE BOUNDARIES AND TOGETHER…… HOW DO FEATURES AND PROCESSES DIFFER AS A RESULT OF PLATE MOVEMENTS?  3 TYPES OF PLATE MOVEMENTS Mantle Mantle (constructive in nature) (Destructive in nature) Mantle (conservative in nature) PLATE MOVEMENTS 3 types of plate movements: Divergent Plate Movement (Away from Each Other) Convergent Plate Movement (Towards Each Other) Transform Plate Movement (Slide Past Each Other)  Oceanic-Oceanic Divergent Plate Boundary When two oceanic plates move away from each other, the rising convection current below lifts the lithosphere producing a mid-ocean ridge, rows of submarine mountains. (The ridge is a high area compared to the surrounding seafloor because of the lift from the convection current below.) Tensional forces stretch the lithosphere and produce a deep fissure forming the spreading center When the fissure opens, pressure is reduced on the super-heated mantle material below. It responds by melting and the new basaltic magma flows into the fissure. The magma then cools and solidifies to form new sea floor.This process is called seafloor spreading. Being less dense than the surrounding older rocks, the new sea floor rises in elevation, resulting in gravitational sliding that pushes the older rocks away from the spreading center. This is known as the ‘ridge push’ force shallow earthquakes are often associated with this crustal stretching basaltic magma from the asthenosphere wells up along any crustal fractures to form submarine/undersea volcanoes. Some of these volcanoes rise above sea level to form volcanic MID-ATLANTIC RIDGE GUESS THE COUNTRY. IT LIES ON THE MID-OCEANIC RIDGE OCEANIC-OCEANIC PLATE DIVERGENCE  DIVERGENT PLATE MOVEMENT OCEANIC-OCEANIC DIVERGENCE When two oceanic plates move away from each other, the rising convection current below lifts the lithosphere producing a mid-ocean ridge, rows of submarine mountains. (The ridge is a high area compared to the surrounding seafloor because of the lift from the convection current below.) MID-OCEANIC RIDGE  DIVERGENT MOVEMENT Tensional forces stretch the lithosphere and produce a deep fissure forming the spreading center When the fissure opens, pressure is reduced on the super-heated mantle material below. It responds by melting and the new basaltic magma ∙ Eg : the Mid Atlantic oceanic ridge is flows into the fissure. This formed when the American plates on process of seafloor spreading the west and the Eurasian plate & results in cooling and solidifying African plate on the east move apart of magma to form new sea floor Video: Seafloor spreading https://youtu.be/k-_Z6p5cjKg Iceland: https://youtu.be/wrhZ-5omHEw  MID-ATLANTIC RIDGE SUBMARINE VOLCANOES YOUNGER ROCKS OLDER ROCKS MID-ATLANTIC RIDGE HTTP://WWW.GEOLOGYIN.COM/2017/07/WHY-ICELAND-IS-BEING-TORN-APART.HTML BIRTH OF SURTSEY ISLAND 3’12” : HTTPS://YOUTU.BE/XHE7-QHETFG  SILFRA FISSURE, ICELAND I’M SNORKELLIN G HERE TECTONIC PLATE TECTONIC PLATE PLATE BOUNDARY  CONTINENTAL-CONTINENTAL DIVERGENCE (OPTIONAL) When two continental crusts move apart, tectonic faults are produced. The central block is lowered relative to adjacent blocks. Volcanic activities take place when magma escapes to the surface Earthquakes take place due to plate movements. VIDEO: HTTP://OCEANSJSU.COM/105D/EXPED_BOUNDARIES/10.HTML CONVERGENT MOVEMENT C+O, O+O, C+C  Continental- Oceanic Convergent Plate Boundary When a thinner and denser oceanic plate converges with a thicker and lighter continental plate, the former descends beneath the latter due to ‘slab-pull’ force into the asthenosphere A long, narrow and deep oceanic trench is formed where the oceanic plate dips into the asthenosphere The movement of the subducting plate is not smooth, producing vibrations called earthquakes along the subduction zone Tip of the subducting oceanic plate melts due to friction with the overriding continental plate, and heat at great depth, producing silica-rich magma magma moves up any breaks or fractures on the overriding continental plate to form a magma chamber, as it is less dense than the asthenosphere and as gases in the magma expands The built-up of pressure in the magma chamber forces magma to escape through the vent on the land surface as lava. Lava cools and solidifies around the vent. Overtime, through repeated eruptions, it accumulates/builds up to form a volcano Edges of continental plate, and sediments near the edges of continental shelf and on the sea floor are contorted and folded to form fold mountains. Volcano: location, formation, chart CONTINENTAL-OCEANIC PLATE CONVERGENCE  7. The movement of 5. The built-up of pressure in the magma the subducting plate chamber forces magma to escape through the is not smooth, vent on the land surface as lava. Lava cools producing vibrations 3. Tip of the subducting oceanic plate and solidifies around the vent. Overtime, called earthquakes melts due to friction with the overriding through repeated eruptions, it along the subduction continental plate, and heat at great accumulates/builds up to form a volcano. zone depth, producing silica-rich magma 4. magma moves up any 6. Edges of continental plate, and breaks or fractures on the sediments near the edges of overriding continental continental shelf and on the sea plate to form a magma floor are contorted and folded to chamber form fold mountains. 2. oceanic trench is formed where oceanic plate dips into the asthenosphere 6 1. When a thinner and 5 denser oceanic plate 2 converges with a thicker thinner and lighter continental plate, the former descends 4 beneath the latter due to ‘slab-pull’ force into the asthenosphere 1 3 7  SOUTH AMERICAN PLATE NAZCA PLATE LOCATE THE PERU-CHILE *TRENCH AND THE ANDES MOUNTAINS (FOLD MOUNTAINS) *Oceanic trench: long, narrow, deep depression in the sea/ocean How about locating them in Google Earth?? OCEANIC-OCEANIC PLATE CONVERGENCE  Oceanic- Oceanic Convergent Plate Boundary When a thinner and denser oceanic plate converges with a thicker and lighter continental plate, the former descends beneath the latter due to ‘slab-pull’ force. A long, narrow and deep oceanic trench is formed where the oceanic plate dips into the asthenosphere The movement of the subducting plate is not smooth, producing vibrations called earthquakes along the subduction zone Tip of the subducting oceanic plate melts due to friction with the overriding oceanic plate, and heat at great depth, producing silica-rich magma (silicon dioxide) magma moves up any breaks or fractures on the overriding oceanic plate to form a magma chamber, as it is less dense than the asthenosphere and as gases in the magma expands The built-up of pressure in the magma chamber forces magma to escape through the vents on the oceanic crust as lava. Lava cools and solidifies around the vent. Overtime, through repeated eruptions, it accumulates/builds up to form a submarine volcano at or near the subduction zone When the volcano builds up and rise above sea level, it forms a volcanic island or a chain of volcanoes known as a volcanic island arc CREATION OF VOLCANIC ISLAND: HTTPS://YOUTU.BE/SJ6FMPNVDDA  VOLCANIC ISLAND ARCS IN THE WORLD Video: https://youtu.be/7m 42rZI3Djo https://www.britannica.com/place/ Ring-of-Fire CONVERGENT OCEANIC-OCEANIC PLATE MOVEMENT NOW YOUR TURN TO PRACTISE ANNOTATING THIS DIAGRAM USE FIG. 2 IN AS2 TO HELP YOU CONTINENTAL - CONTINENTAL PLATE CONVERGENCE CONVERGENT CONTINENTAL-CONTINENTAL PLATE MOVEMENT (COLLISION ZONE) when both continental plates collide, neither tends to sink because their densities are similar. ∙ Instead, continental crust buckles & folds ∙ Fold mountain ranges are formed ∙ eg : the Himalayas are formed when Indian plate collided with Eurasian plate & Alps was formed when African plate drifted towards Eurasian plate ∙ Little volcanic activity occur because rocks from the crust do not sink deep into the mantle. ∙ Earthquakes, faulting & folding are common. Rise of the Continents 3’22”: https://youtu.be/npm66QXfr0g 70 millions in 2 minutes – The Himalayas forming: https://www.youtube.com/watch?v=S1A43yUeLik CONVERGENT CONTINENTAL-CONTINENTAL PLATE MOVEMENT (COLLISION ZONE) Crus t Mantle TRANSFORM PLATE MOVEMENTS (ENRICHMENT ONLY) Plates sliding past one another at conservative plate boundary: ∙ They occur when 2 plates slide past each other. ∙ Great amount of stress built up in these areas, but there is little volcanic activity & little crustal material is destroyed ∙ Eg : the San Andreas Fault in California, USA Animation: https://www.geolsoc.org.uk /Plate-Tectonics/Chap3-Plat e-Margins/Conservative/Sa n-Andreas-Fault The San Andreas Fault zone is an example of a conservative boundary where the Pacific Plate on which Los Angeles sits is moving slowly northwestward relative to the North American Plate on which San Francisco sits. PLATE MOVEMENTS, IN TOTALITY The figure below will replace Fig.5 for Question 4(a)(i) Source: https://ngdc.noaa.gov/mgg/ocean_age/data/2008/image/age_oceanic_lith.jpg Suggested Answers: Q.13 (a)  The core (inner core and outer core) is about 3,500 km thick whereas/while/however the mantle is about 2,900 km thick.  The inner core is extremely hot with temperatures of between 4,000°C and 5,000°C, and the outer core is very hot with temperatures of between 3,000°C and 4,000°C while the temperature of the mantle is between 800°C and 3000°C.  The inner core is solid, and the outer core is liquid. However, the mantle is mostly solid. Note: For the second bullet point, you may also combine the inner and outer core temperatures and present your answer as follows:  The temperature of the core is between 3,000 C and 5,000 C while the temperature of the mantle is between 800 C and 3,000 C. (b)  Plate boundary X in Fig.23 is an oceanic-oceanic divergent plate boundary where the mid-oceanic ridge is formed.  When magma that is heated by the earth’s core rises from the mantle towards the oceanic crust, it cools and spreads out beneath the plates. In the process the plates above it are pushed apart by the diverging mantle convection currents, causing them to move away from each other.  This movement results in fractures at the zone of divergence in the oceanic plates, leading to the formation of the divergent plate boundary at X.  Plate boundary Y in Fig.23 is an oceanic-continental convergent plate boundary where oceanic trenches are formed.  When magma that had risen and spread out beneath the plates cools, it sinks and the converging mantle convection currents pull the plates together.  As both plates converge, the denser oceanic plate subducts under the less dense continental plate at the subduction zones (area directly below Y), slab-pull force occurs and pulls the rest of the plate behind it.  This process results in the formation of the convergent plate boundary at Y. Q.4 (a)(i)  Fig.5 shows that the age of the rocks directly adjacent to Africa along the equator is relatively old, around 80-120 million years.  Moving further along the equator into the Atlantic Ocean, most rocks are relatively younger closer to the plate boundary, around 1 – 20 million years old.  Moving along the equator towards South America, the age of the rocks is older again, with those directly adjacent to the South American continent being between 110 and 120 million years old. (Tips: Separate the area into sections and describe the variations in the age of the rocks between those sections.) 4 (a)(ii)  Feature A is a mid-oceanic ridge.  Seafloor spreading takes place because two oceanic tectonic plates move apart due to convection currents circulating in the Earth’s mantle.  This process is shown in Fig.6 with two oceanic crusts diverging at A in the same direction as the respective convection currents beneath them.  When magma is heated by the core, it rises in the mantle towards the oceanic crusts.  As the rising magma cools nearer the oceanic crusts, it spreads apart and pulls the oceanic crusts above it away from each other.  This causes the oceanic plates to diverge, resulting in fractures at the zone of divergence.  This process is called sea floor spreading. Practice Question for Plate Movement (Annotation) Annotate the cross-section A – B on the next page to show the tectonic processes responsible for the formation of the volcanic island arc and oceanic trench.  Practice Question on Plate Movement Suggested Answers When the submarine volcanoes build up and rise The convergence of the above the sea level, they form oceanic Philippines plate and a chain of volcanic islands or oceanic Pacific plate (1m) volcanic arc. (1m) causes the denser Pacific plate to sink beneath the lighter Philippines sea plate Cross-Section A to B due to slab-pull force. (1m) A B The Mariana trench is The built-up pressure in the formed. magma chamber forces the magma to escape through the vents and erupts onto the earth’s Mariana Trench (1m) surface as lava. (1m) The lava cools and solidifies. Repeated eruptions form submarine volcanoes over time. (1m) Oceanic Pacific Oceanic Philippines Plate (1m) Plate (1m) Note: 1m for correctly drawing the arrows of plate movement Increasing pressure in the mantle The tip of the subducting plate melts due to friction with the causes the magma to rise through overriding Philippines sea plate and heat at great depth (1m), cracks or fractures on the overriding producing silica-rich magma in the mantle. (1m) oceanic plate to form a magma chamber. Plate Tectonics An Introduction Today’s Lesson Objectives Provide brief overview of the topic “Plate Tectonics” Highlight relevance and importance of the topic Brief introduction to Continental Drift Theory FEW PICS, ONE WORD Plate Tectonics What is a word or phrase that can help to encapsulate what you see in each slide? _____ ______  How do you feel after looking at the images? Checking In Why do you feel this way?  Key Concepts shown in the pictures: 1. Impacts of Volcanic Eruptions 2. Impacts of Earthquakes 3. Rescue & Recovery (Rebuilding) Importance of understanding impacts of geological Few pics, disasters? one word/phrase Make generalisations about our earth and how the Earth’s forces have brought about significant impacts on people, especially on the survivors?  Why do people choose to stay in a The issue tectonically active area?  What do you think is the link of the concepts/ words/ phrases that you inferred from the photos, to ‘Population’? increase population growth —> increase population The link density increase likelihood of people living in hazard-prone places —> increase their vulnerability  EU 2: An understanding of the tectonic forces can enable humans to harness Earth’s resources and respond to its disasters more effectively in order to benefit society. EU 3: The level of preparedness of a country can determine the severity of damage caused by tectonic activities in order to improve its capacity to respond and manage the tectonic disasters. EUs A good awareness of the natural environment, especially tectonic features and processes is important in increasing people’s preparedness towards tectonic hazards.  What do you know about tectonic landform Optional: features? What do you know Refer to about tectonic Padlet Post processes? in Google Classroom What questions do you have about the topic pf Plate Tectonics? Do continents drift? Jigsaw Puzzle activity Do continents drift? What were the evidences that show that our continents moved apart? What was/were the major flaws in the Continental Drift Theory? Alfred Wegener: Great Minds https://youtu.be/nbU809Cyrao  Appalachian Mts of eastern US correspond geologically with Mts in NW Europe Remains of Mesosaurus found Rocks of similar type, only in Africa and age, formation and Brazil. structure occur in SE Brazil & South Africa  Evidence of glaciation in Brazil and central India. Coal (formed under warm, wet climatic conditions found beneath Antarctic ice-cap. https://quizlet.com/234922763/evidences-of-continental-drift-theory-diagram/ The changing Earth Early Earth 5’16”: https://youtu.be/QDqskltCixA Do continents drift? What was/were the major flaws in the Continental Drift Theory? Alfred Wegener: Great Minds https://youtu.be/nbU809Cyrao The Problem with Continental Drift Theory His theory was rejected because he was not regarded as an expert in the field (He was a meteorologist!) He could not explain how solid continents were able to move on Earth The Problem with Continental Drift Theory How has Alfred Wegener’s story reflected the value of courage?  Complete Slides: LA1 Identify Earth’s structure Homework Describe the distribution of some tectonic features in the world Name : _________________________ ( ) Class : Year 2 / ________ Date : __________ SUGGESTED ANSWERS Plate Tectonics Resource Package ISSUE: Is living near tectonically active areas worth the risk? A fisherman steers a traditional boat as Mount Agung erupts, seen from the Kubu sub-district in Karangasem Regency on Indonesia's resort island of Bali on Nov 28, 2017. (Source: 2017, The Straits Times, https://www.straitstimes.com/asia/se-asia/mount-agung-erupts-different-stages-of-a-volcano-eruption, Theme : The World as Interacting Systems LA 1 Topic : Plate Tectonics – Internal Structure of Earth & Plate Boundaries Enduring Understanding The movement of tectonic plates can constantly change the surface of the Earth to reach a state of equilibrium. Getting started Complete the diagram below that shows the Four Spheres of the Earth. (Source: https://socratic.org/questions/583de45f11ef6b1218cdb389) (a) What are natural hazards? Natural hazards are naturally occurring events that have the potential to cause harm and destruction. (b) What are some natural hazards associated with the sphere at the bottom right-hand corner? Earthquakes, volcanic eruptions, and landslides (c) Is Singapore likely to experience such natural hazards mentioned in (b)? Explain your answer. No, Singapore is not likely to experience such natural hazards. This is because Singapore is not in an area that is tectonically active/not near plate boundaries. (d) What are you curious to find out in this unit? Your own responses: Why are volcanoes found only in certain areas? (will be uncovered later) Note: Natural Disasters – Naturally occurring events that have caused harm and destruction. 2 A The Earth’s Structure Watch the documentary: ‘Inside the Earth’ https://www.youtube.com/watch?v=faXNNHcyXXk and “The Early Earth and Plate Tectonics” by National Geographic from Youtube at http://www.youtube.com/watch?v=QDqskltCixA. Use the information that you have gathered from the documentary to respond to the following questions. 1. Fig. 1 shows the Earth’s interior structure. Fig. 1: The Structure of the Earth (Source: GCSE Bitesize, BBC, accessed on 4 April 2014 from http://www.bbc.co.uk/schools/gcsebitesize/geography/natural_hazards/tectonic_plates_rev1.shtml) Name and describe the Earth’s layers labelled A to D. Layers Name Est. Temperature Depth / Thickness Material Crust Temperature About 70 km thick Solid rocks & soil dependent on forming landforms A weather & climate of the atmosphere above it Mantle 800 – 3000ºC About 2900 km thick Semi-molten rock B called magma Outer Core 5000ºC About 2200 km thick Liquid Iron & Nickel C Inner Core 6000ºC About 1250 km thick Solid Iron Sphere D Radioactive materials e.g. Uranium 3 2. Study Fig. 2 below and fill in the blanks. Fig. 2: Earth’s Crust (Source: http://3.bp.blogspot.com/_zwaRuUhzrcM/SgkebE2_HfI/AAAAAAAABgQ/1AIHTc1IVoE/s400/Picture5.jpg) The ____ crust _______, which is the most outermost layer of the earth, is broken into tectonic plates that move in relation to one another. These tectonic plates are part of the __ lithosphere___, which includes the ___ crust _____ and the uppermost _ mantle_. Tectonic plates can be made up of either _ oceanic _ crust _____, _ continental ___ _ crust ______ or a combination of both. Oceanic ______ __ crust ____ are found beneath deep oceans and are _ denser than continental __ crust__, which are located beneath the earth’s continental land masses and under the shallow seas close to continents. Oceanic crusts are denser than _ continental___ _ crust__ as they consist mainly of basalt, a heavy and dense rock formed from magma which has cooled quickly. Continental__ _ crust__ consist of lighter rocks, including granite, which age range widely from very recently formed to nearly 4 billion years old. (Adapted from All About Geography: Upper Secondary Physical Geography, pp.84) 4 3. Study the plate tectonic map below and match the alphabets to the corresponding name each plate. Plate Tectonic Map (Source: https://s-media-cache-ak0.pinimg.com/originals/85/e4/05/85e4058589832ba953553bc4ba1987f9.jpg) Major Plates Minor Plates I K African Plate Arabian Plate L Caribbean E Indo-Australian Plate Plate N C Antarctic Plate Cocos Plate D F North American Plate Nazca Plate J Juan de Fuca A Eurasian Plate Plate South American G M Philippine Plate Plate B H Pacific Plate Scotia Plate O Okhotsk Plate 5 B Global distribution of volcanoes, oceanic trenches and earthquakes in the world. Access the following EduGIS link: https://moe-edugis.maps.arcgis.com/apps/View/index.html?appid=36ec82e26dc143e6a99ae8a0 35ae50c6 (a) Select ‘Topographic’ in ‘Basemap gallery’ + ‘Volcanoes’ in ‘Layers’ Describe the distribution of volcanoes in the world. Use compass directions and knowledge of continents/ countries/ regions to help you in your description. Ans: 1. The volcanoes are found along the plate boundaries. Along the boundary of the Pacific Plate, there are many volcanoes to the East, West and North of the Pacific Ocean. For example, there are volcanoes along the coast of USA (East of Pacific Ocean) and along the coast of Japan and the Philippines (West of Pacific Ocean). There are also many volcanoes on the Indonesian islands. They are found to the North of the Indo-Australian Plate, and to the West of the Philippines Plate. There are also volcanoes along plate boundary North of Africa and in the Atlantic Ocean, where Iceland is. 2. The area with high concentration of volcanoes near the Pacific Ocean described above, is called the Pacific “Ring of Fire”. 3. However, not all volcanoes are located along the plate boundaries. Some can be located in the middle of the plate, away from the boundaries. An example is the Hawaiian islands, found in the middle of the Pacific Ocean/Pacific Plate, with volcanoes such as Kilauea. 6 (b) Add ‘Oceanic Trenches’ in ‘Layers’ to your existing map. Describe the distribution of *oceanic trenches in the world. Use compass directions and knowledge of continents/ countries/ regions to help you in your description. * “Oceanic trenches are long, narrow depressions on the seafloor”, National Geographic https://www.nationalgeographic.org/encyclopedia/ocean- trench/ Ans The oceanic trenches are also found along the plate boundaries and near the volcanoes. They are also found in the Pacific “Ring of Fire”, along the boundary of the Pacific Plate, Indo-Australian Plate, the Philippine Plate and the Nazca Plate. (c) Access the following link to study the global distribution of earthquakes: https://www.researchgate.net/figure/Worldwide-earthquake-distribution-showing-the-deepest- earthquake-locations-South_fig1_326011745. In conjunction with the answers that you have given in Qus 1(a) and 1(b), Generate TWO similarities you observed in the distribution of volcanoes, oceanic trenches and earthquakes. Ans Volcanoes, oceanic trenches and earthquakes are found along plate boundaries, such as at the Pacific “Ring of Fire.” Volcanoes and earthquakes can occur at locations in the middle of the plate (but not oceanic trenches). (d) Generate TWO inferences you can make from your observations in 1(c). Ans 1. Plate movements that take place along these boundaries cause the formation of volcanoes and oceanic trenches, and the occurrence of earthquakes. 2. There are different types of plate movements responsible for the formation of the different features. 7 C. How Convection Currents in the Mantle Drives Plate Movement Fig. 3 Fig. 4 (Source: http://www.geography.learnontheinternet.co.uk/images/tectonics/ConvectionCurrent_labelled.jpg) Using Fig.4 and information from the textbook, explain why and how do plates move. 1. When radioactive decay occurs in the core, heat is released. The heat causes the semi-molten rocks in the mantle to become less dense, expand and rise towards the surface. 2. The rising convection currents then spread out beneath the plates, and drag them apart, causing divergent plate movement.. 3. The semi-molten rocks then lose heat and sink towards the core. Convergent plate movement occurs where the convection currents collide and pull the plates towards each other. 4. The sinking mantle materials then get heated up again as it nears the core and the whole process repeats. 5. Besides convection currents, slab-pull force also contributes to tectonic plate movement. 6. Slab-pull force occurs when a denser oceanic plate is forced beneath a less dense continental plate or oceanic plate by gravity in a process called subduction. 7. As the plate subducts, the denser oceanic plate sinks deeper into the mantle under its own weight, pulling the rest of the plate with it. The subducting plate drives the downward moving portion of convection currents, contributing to further convergence. 8. The mantle materials which are found away from where the plates subduct drive the rising portion of convection currents. 8 Enrichment Refer to Fig.3 below, conduct a research to find out what were some compelling evidence Alfred Wegner provided to support the continental drift theory. “The belief that continents have not always been fixed in their present positions was suspected long before the 20th century. It was not until 1912 that the idea of moving continents was seriously considered as a full-blown scientific theory -- called Continental Drift -- introduced in two articles published by a 32-year-old German meteorologist named Alfred Lothar Wegener. He contended that, around 200 million years ago, the supercontinent Pangaea began to split apart. Alexander Du Toit, Professor of Geology at Witwatersrand University and one of Wegener's staunchest supporters, proposed that Pangaea first broke into two large continental landmasses, Laurasia in the northern hemisphere and Gondwanaland in the southern hemisphere. Laurasia and Gondwanaland then continued to break apart into the various smaller continents that exist today.” (Extracted from This Dynamic Earth: The Story of Plate Tectonics – A Historical Perspective, https://pubs.usgs.gov/gip/dynamic/historical.html ) 9 Name : _________________________ ( ) Class : Year 2 / ________ Date : __________ LA 2 - Suggested Answers Plate Tectonics Resource Package ISSUE: Is living near tectonically active areas worth the risk? A fisherman steers a traditional boat as Mount Agung erupts, seen from the Kubu sub-district in Karangasem Regency on Indonesia's resort island of Bali on Nov 28, 2017. (Source: 2017, The Straits Times, https://www.straitstimes.com/asia/se-asia/mount-agung-erupts-different-stages-of-a-volcano-eruption, Theme : The World as Interacting Systems LA 2 Topic : Plate Tectonics – Internal Structure of Earth & Plate Boundaries Essential Questions: ▪ What is Plate Tectonics? (F) ▪ How is the Earth an unfinished planet? (C) Types of Plate Movement I. Convergent Plate Movement 1. Continental - Continental Convergence 2. Oceanic - Oceanic Convergence 3. Continental - Oceanic Convergence II. Divergent Plate Movement: 4. Oceanic-Oceanic Divergence (Note for Enrichment Only: Continental-Continental Divergence) III. Transform Plate Movement 5. Two plates sliding past each other Fig. 1: An overview of the types of plate movement Source : https://sites.google.com/a/ocsb.ca/cgc-1d/a-unit-2-3-natural-disasters--earthquakes/11-tectonics-review 2  How to annotate a diagram To annotate a diagram means to add notes to a diagram for the purpose of describing and/ or explaining landform features and processes. Tectonic Landform Tectonic Processes features features phenomena o types of o fold o earthquakes o Convection plates mountains, (at times o Divergence (continental o volcanoes accompanie (of O-O or oceanic), o volcanic d by plates) o names of islands tsunami) o Convergenc plates (in o oceanic e (of C-O accordance trenches plates, O-O to data o mid-oceani plates, C-C given), c ridge plates) type of o Subduction plate (at boundary destructive Step 1: (destructive plate *Labelling vs boundary) constructive o Sea-floor plate spreading boundary) o Compression o new (of upper oceanic crust during crust/ new tectonic sea floor folding) *Includes drawing of arrows to show direction of plate movement Step 2: Number the sequential order of the processes of formation. Numberin g Descriptions and/ or explanations of o Tectonic features Step 3: o Processes Annotatin g o resultant landforms as well as o tectonic phenomena. Step 4: Adding Add a title to show the purpose of the annotation. a title 3  PRACTICE ON ANNOTATION OF DIAGRAMS TASK: Watch the animation of the various types of plate movement. Study the two examples of annotation of diagram (Fig. 1 and Fig. 2) Annotate Fig. 3 and Fig. 4. Tectonic Convergence: Continental-Continental plates 1. Watch animation of this movement from the Geological Society of UK “Continental/Continental: The Himalayas from http://www.geolsoc.org.uk/Plate-Tectonics/Chap3-Plate-Margins/Convergent/Continental-Collisi on Example 1: How to ANNOTATE a diagram showing the convergence of two continental plates Fig. 1 Tectonic convergence between continental plates resulting in the formation of fold mountains (Source: © 2007 Eric H. Christiansen and W. Kenneth Hamblin http://www.explanet.info/Chapter08.htm) 4  Tectonic Convergence: Oceanic-Oceanic plates 2. Watch animation of this movement from the Geological Society of UK “Oceanic/Oceanic: Caribbean Islands” from http://www.geolsoc.org.uk/Plate-Tectonics/Chap3-Plate-Margins/Convergent/Oceanic-oceani c-collision Mariana trench video: https://www.youtube.com/watch?v=Y2tm40uMhDI Example 2: How to ANNOTATE a diagram showing the convergence of two oceanic plates. Fig.2 Convergence between oceanic plates resulting in the formation of a volcano (Source: Levin, H.L. (2005). The Earth through Time (8th edition). Wiley.) 5  Tectonic Convergence: Oceanic-Continental plates 3a. Watch animation of this movement from the Geological Society of UK “Oceanic/Continental: The Andes from http://www.geolsoc.org.uk/Plate-Tectonics/Chap3-Plate-Margins/Convergent/Oceanic-contine ntal b. Annotate Fig. 3 to explain the convergent movement between oceanic and continental plate. (5) (6) (2) (5) (6) (2) (1) (1) (7) (4) (4) (7) (3) (3) \\ Title: _Oceanic-continental plate convergence with associated landforms___ (adapted from http://geography.parkfieldprimary.com/hazards/plate-tectonics) Fig. 3 6  Tectonic Divergence: Oceanic-Oceanic 4a. Watch animation of this movement from the Geological Society of UK “Oceanic/Oceanic: Divergence from https://www.geolsoc.org.uk/Plate-Tectonics/Chap3-Plate-Margins/Divergent/Mid-Atlantic-Ridg e Mid-Atlantic Ridge video: https://www.youtube.com/watch?v=bGye6vlOpbY b. Annotate Fig. 4 to explain the divergent movement of two oceanic plates. (1) (2) (3) (4) (5) (1) (2) (3) (4) (5) Title: __ Oceanic-oceanic plate divergence with associated landforms ____ Fig. 4 7  5. Watch animation of this movement from the Geological Society of UK “Transform Plate Movement: from https://www.geolsoc.org.uk/Plate-Tectonics/Chap3-Plate-Margins/Conservative/San-Andreas -Fault Fig. 5 Diagram showing transform plate movement (http://slideplayer.com/4863554/15/images/10/Transform%20boundary%20(side-to-side%20plate%20movement).jpg) Divergent Movement between Continental Plates Resulting in the Formation of a Rift Valley Watch animation of this movement from the Geological Society of UK “Continental Rifting’ from https://www.geolsoc.org.uk/Plate-Tectonics/Chap3-Plate-Margins/Divergent/Triple-Junction (Source: McCarthy, T & Rubidge, B. (2005). The Story of Earth and Life. Struik Publishers: Cape Town) 8  SUMMARY You can refer to the following information: ▪ All About Geography (Physical Geography Upper Secondary) Textbook, Chap. 2 Page 84-93 The table below shows the types of plate movement and their resultant physical features / landforms or tectonic activities. Complete the table below as a summary of what you have learnt. Plate Types of Processes Resultant Features or Named Examples Boundaries plates (Short descriptions) Tectonic Phenomena & Location & Movements Convergent / ▪ Both plates are of ▪ Fold Mountains ▪ The Himalayas destructive same density and passing through boundary buoyant thus no India, Pakistan, - Move subduction takes Afghanistan, towards each Between place China, Bhutan Continental other / Collide ▪ Plate edges are and Nepal plates compressed and (Between Indian buckled up Plate and ▪ Earthquakes Eurasian Plate) ▪ 2015 Nepal Earthquake ▪ One oceanic plate ▪ Oceanic Trench ▪ MarianaTrench subducts under the (Between other (possibly as it Pacific Plate moves faster than the and slower other or it is denser moving than the other) ▪ Submarine/Undersea Philippine Between volcanoes Plate) Oceanic ▪ Volcanoes Plates ▪ Volcanic islands ▪ Mariana Islands ▪ Earthquakes ▪ Earthquake in the Northern Mariana Islands region July 29 2016, Magnitude 7.7 ▪ The denser oceanic ▪ Oceanic Trench ▪ Peru-Chile plate subducts under Trench less dense continental (Between plate Nazca Plate Between ▪ The edges of the ▪ Submarine and South Continental continental plate volcanoes American Plate) & Oceanic buckle up and fold ▪ Volcanoes ▪ Cotopaxi plates Volcano in Ecuador ▪ Fold mountains ▪ Andes ▪ Earthquakes ▪ Chile Earthquake, 27 (Pls refer to Y3 Textbook eg of Sumatra – the nearest plate Feb 2010, boundary to Singapore) Magnitude 8.8 9  Divergent / ▪ As two oceanic ▪ Mid-oceanic Ridge ▪ Mid-Atlantic constructive plates move away Ridge in the Boundary from each other, Atlantic Ocean - Move tensional forces (Between away from form a spreading North each other centre ▪ Submarine/Underse American Plate a volcanoes and Eurasian ▪ Volcanoes Plate) ▪ Volcanic islands ▪ Azores Between (Iceland is formed as a result of this divergent Oceanic movement as well as plates hot spot volcanic activity, an active volcano called Eyjafjallajökull erupted in 2010 and caused significant economic damage globally). ▪ Earthquakes ▪ Minor earthquakes >5 magnitude Between ▪ As blocks on either ▪ Rift Valleys ▪ Black Forest Continental side of the plates Mountains in plates move apart along fault Germany lines, the middle block ▪ Block Mountains sinks. ▪ Great African Rift ▪ As blocks on either Valley in East side of the plates Africa collide along fault lines, the middle block rises. Plate Types of Processes Resultant Features or Named Examples Boundaries plates (Short descriptions) Phenomena & Location & Movements Transform / Between ▪ Plates slide past each ▪ Fault Line ▪ San Andreas Conservativ Continental other along transform Fault in e Boundary plates faults (could be ▪ Earthquake California, USA - slide past opposite directions / ▪ 1994 Northridge each other same direction but Earthquake in one moving faster Los Angeles, than the other) USA (Between Pacific Watch Plate & North http://www.geolsoc.org.uk/Plate -Tectonics/Chap3-Plate-Margin American Plate) s/Conservative/San-Andreas-F ault 10 Hot Spot – Hot spots ▪ Heat from hot spot ▪ Volcano / Volcanic ▪ Hawaiian Islands Not at plate may be on, melts through the island in the Pacific boundary near to, or crust Ocean, off the far from (see diagram below) coast of USA tectonic (Pacific Plate) plate - Mauna Loa boundaries Volcano (See fig.1) ▪ Galapagos (*FOR Islands in the Enrichme Pacific Ocean, off nt ONLY) the coast of Ecuador (Nazca Plate) Watch http://www.geolsoc.org.uk/Plate-Tectonics/Chap3-Plate-Margins/Mid-plate/Hawaii an-Islands Formation of Hot Spot Volcanoes Fig 1 Diagram showing Hot Spot Volcanoes (Source: http://www.tulane.edu/~sanelson/images/hotspot.gif) Adapted from: 2019_ Geog_Year2_PlateTect_PlateMovements Annotations_AS4_TC_KBY 2018_ Geog_Year2_PlateTect_PlateMovements Annotations_AS4_KBY 2016_Geog_Year2_PlateTect_PlateMovements Drawing_AS3_RC GeY2_PlateTect_PlateMovt_FA1_kohby2012_revised based on GeS2_PlateTectVolImpactsWSJuly10_SW _____________________________________________________________________________________________________________ Be a responsible and active citizen who actively seeks to apply the knowledge, perspectives and skills of geography in life situations of an increasingly interdependent global community 11  Raffles Girls’ School (Secondary) Raffles Programme Geography For Global Citizens Year Two (2024) Name : _________________________ ( ) Class : Year 2 / ________ Date : __________ LA3 – Suggested Answers Plate Tectonics Resource Package ISSUE: Is living near tectonically active areas worth the risk? A fisherman steers a traditional boat as Mount Agung erupts, seen from the Kubu sub -district in Karangasem Regency on Indonesia's resort island of Bali on Nov 28, 2017. (Source: 2017, The Straits Times, https://www.straitstimes.com/asia/se -asia/mount -agung-erupts-different-stages-of-a-volcano-eruption, Theme : The World as Interacting Systems LA 3 Topic : Volcanoes Fig. 1 shows the structure of a volcano. Match the alphabets to the parts of the volcano, and to the definitions. E D C B A (Source: https://planbee.com/blogs/news/facts-about-volcanoes-for-children-and-teachers) Parts Definition A Pipe/ Conduit Reservoir of molten rock within or beneath the earth’s crust B Vent Any opening at the Earth’s surface through which magma erupts or volcanic gases are emitted C Magma Passage in a volcano through which magma Chamber and volcanic gases rise towards the surface D Secondary Smaller cones that build up on the sides of a cone volcano E Crater Bowl-shaped depression produced by impact of volcanic activity on summit of volcano 2 2. Sequence the following processes in the correct order to explain the formation of a volcano. Write the number 1 – 5 in the brackets provided. ( 1 ) ( 2 ) ( 3 ) ( 4 ) ( 5 ) 3 Source: Geo Factsheets Number 373 4 Compare shield volcanoes and stratovolcanoes using appropriate criteria. Shield Volcanoes Stratovolcanoes How Are They Similar In terms of shape, they are both cone-shaped. In terms of formation, they are both formed when magma rises and erupts as lava on the surface of the earth’s crust, cools and solidifies. In terms of location, they are formed along plate boundaries. How Are They Different Basic Lava Acidic Lava Low silica content Type of High silica content Fluid/Less viscous, can travel long Lava Viscous, flows more slowly distance Cools faster, solidifies quickly Cools slowly Usually Lower temperature Usually Higher temperature Violent eruptions Quiet eruptions Type of Gas and steam are trapped and do Gas and steam escape more easily, not escape easily, resulting in does not trap gas. Eruption explosive eruptions. High/Tall volcano Broad summit Concave profile Broad-based Shape Steeply sloping sides Gently sloping sides Common near Convergent plate boundaries (when subduction takes Common near Divergent plate place) boundaries Reference: https://www.tes.com/teaching-resource/volcano-formation-6426887 5 Introduction to Population Studies  Are you a Demographer? Pop Quiz 5 questions  Question 1 How may people live on Planet Earth today ?  Question 2 By how much does the world population increase each day ? Question 3 Which country has the longest life expectancy ? Question 3  Question 4 Which of the following is most densely populated ? Question 4  Question 5 Which country has the shortest life expectancy? Question 5  Population Studies - What will you be learning? World Population Trends Population Growth and Concepts Population Pyramids Population Policies Inclusive Housing Can the world’s resources support its growing population? Lesson 2: World Population Trends EQ: Does population size matter for socio-economic development? EU: Changing population dynamics can present opportunities and challenges that may influence the earth’s carrying capacity. EQ: Does population size matter for socio-economic development? EU: Changing population dynamics can present opportunities and challenges that may influence the earth’s carrying capacity. What is carrying capacity? The number of people an area of land can support. Use OSO to describe trends OSO – Obvious, Significant, Odd How do we describe trends? 1. Describe the overall trend. 2. Give data from both the x and y axis. 3. Mention any anomalies or figures that may not fit the trend.  What is Trend? A general direction in which something is developing or changing. Usually seen as change over time. Relevant to line graphs and bar graphs.  Useful Verbs to Describe Trends Increase/rise Decrease/decline/drop/fall/dip Plummet/plunge No change Remain constant Fluctuate Peak Plateau Examples of Adjectives to Describe Degree of Change Adjectives Meaning Slight Very small Sharp Sudden, large change Dramatic Sudden, very large change Steady An even change Gradual A slow change over a long period of time  Command word is ‘Describe’, do not attempt to explain Make reference to the chart a) With reference to Fig 1, describe the trend of human population growth from Year 1 AD to 2000 and beyond. Fig. 1 shows that the rate of human population growth was slow from Year 1 AD to around 1800. This can be seen from the gentle gradient which shows a small increase in population from about 0.2 billion in Year 1 AD to about 1 billion in 1800. From 1800, the rate of population growth started to become more rapid. The steep gradient, especially after 1900, indicates a Fig. 1 Use data rapid rise in population from 1.5 billion in 1900 to more than 5 billion in 2000. To answer ‘…and beyond It is projected to continue to rise at a rapid rate to reach 10 billion by 2050  Improvements in nutrition, clean water, medical care have lowered death rates Industrial revolution Reasons for the trends in the 18th century - technological development and large-scale agriculture increased the supply of food → less malnutrition and starvation. Vaccination and High rates of infant mortality and advances in medicine shorter life expectancy caused lowered the slower population growth. Main incidence of disease. causes of death include disease, famine and war  b) What message about human population growth is conveyed in the cartoon in Fig. 1? Fig. 1 - Rapid population growth will strain world food delivery systems. This can be seen by the train representing the world food delivery systems having a hard time going up the slope. This indicates how it may be hard to ensure everyone has access to food supplies if the population continues to increase at a rapid rate. Fig. 1  b) What message about human population growth is conveyed in the cartoon