Volcanoes and Earthquakes

Transcription

1 Explore and Discover... Explore the gallery. Use the eight questions to guide you. These are based on the displays students have found most interesting, and that are particularly useful for your school studies. Teacher information Gallery visited Suitable for Key Stage 3 (ages 11 14) Curriculum links Pre-visit preparation Concepts Post-visit Science: the composition of Earth, the structure of Earth, the formation of igneous rocks. Geography: key processes in plate tectonics, how human and physical processes interact to influence and change landscapes, environments and the climate. Vocabulary: plate tectonics, plate boundaries, earthquakes, volcanoes, eruptions, igneous, magma, lava, continental crust, oceanic crust, tsunami. Plate tectonics, fossils as evidence for plate tectonics, geological interactions at plate boundaries and their impacts on landscape and people, the structure of Earth, different types of volcanic eruption, formation of igneous rock, why the structure of igneous rock varies, defence against the impact of earthquakes on people. Students can continue to research ideas for reducing the impact of earthquakes on people. Students can discover more about volcanoes and earthquakes by exploring online at Natural History Museum Explore and Discover 1

2 1 What do you notice about the location of most of the active volcanoes and large earthquakes? Most of the active volcanoes and large earthquakes are on or near plate boundaries. Can you explain what you have noticed about their location? If not, come back to this question after exploring the gallery. Answers will vary, but fuller answers should include that the movement of tectonic plates towards each other, sliding past each other, or away from each other, causes volcanoes and earthquakes on or near the edges of plates/plate boundaries. IMPORTANT: Students choose EITHER 2a, 2b or 2c to answer. Please make sure students realise this. 2a In what year did it erupt? Tambora: 1815 Krakatoa: 1883 How did it affect people? Tambora Answers may include: Thousands of people died instantly. Ash smothered the region causing crop failure, starvation and disease. North America, Iceland and Europe experienced a year without summer. Harvests failed causing famine, food riots and outbreaks of typhus and plague. Krakatoa Answers may include: Tsunami waves damaged coastal towns and villages on surrounding islands. Ash and rock rained down on surrounding islands. Choose two facts about the volcano that you find most interesting. Write them here: A range of facts may be chosen from the display, and could include: Tambora Any of the human impacts described above. Fine ash and sulphuric acid formed a veil across the Sun. Mount Tambora lost more than one kilometre of height in the eruption. The peak was replaced with a shallow, five-kilometre-wide caldera. Krakatoa Either of the human impacts described above. Krakatoa exploded with the force of 1,000 atomic bombs. The explosion was heard 3,000 kilometres away in Australia. Krakatoa disappeared to leave a massive, sea-filled crater. Natural History Museum Explore and Discover 2

3 Find the pumice fragments from the Krakatoa eruption. Why were the pumice fragments able to float on the sea all the way to Africa? Answers will vary and could range from the simple to the more detailed: The pumice fragments are light enough to float. The pumice fragments are light enough to float because of gas contained within them. The pumice fragments are light enough to float because gas bubbles formed in the magma as it hit regular air pressure, during an eruption. The gas bubbles were frozen in the rock as it rapidly cooled. 2b If it s not too crowded, touch the pillow lava specimen, and look at the image behind it. What caused this lava to cool down? The lava cooled down because it came into contact with cold sea water. Find the Hawaiian rocks in the display to the right. Choose one and explain how the way it was formed affected how it looks. Answers should include key points from the information displayed about one of the following rocks: Pāhoehoe lava The lava flows slowly. As the surface begins to cool and solidify, the lava underneath continues to flow, creating folds. Pele s hair The golden strands form when tiny pieces of magma are thrown into the air and spun by the wind into volcanic glass. `A`ā lava The surface of the lava flow cools and hardens while the inner part continues to flow, breaking it into sharp, angular shapes. 2c Read the introduction about supervolcanoes. Choose two facts about them you find most interesting. Write them here: A range of facts may be chosen from the display, and could include the following: Supervolcanoes are more than 1,000 times larger than a normal volcano. Supervolcanoes release ash clouds that block out the Sun and change Earth s climate, causing death and destruction. Supervolcano eruptions are extremely rare. The last one was 74,000 years ago, at Lake Toba, Sumatra. The Lake Toba eruption cooled Earth by 5 C and nearly caused the extinction of humans. Scientists have identified eight supervolcanoes around the world. There is very little chance a supervolcano will erupt in our lifetime, but you can never be sure. Which supervolcano is nearest to the UK? How do you think it would affect the UK if it erupted? Phlegraean Fields, Italy. Ash clouds could block out the Sun and change our climate, causing death and destruction. Natural History Museum Explore and Discover 3

4 3 Compare the rock specimens on display. What connects all the four specimens you see here? They are all made from cooled magma or lava. Students may alternatively state they are all igneous rocks. What one word describes the type of rock on display? Igneous. Choose two of the rocks and compare their differences. Explain why they are different to each other. Comparisons between two of the four rocks on display should refer to the features stated below, eg gas bubbles, glassy appearance, crystals. Some students will be able to explain that the differences between the rocks features are determined by gas and silica content and time taken for cooling. Obsidian Lava cooled extremely quickly to form volcanic glass. There was no time for crystals to form. Andesite The crystals in the andesite cooled more slowly than the rest of the rock, showing two stages of cooling. Slow cooling allows crystal formation. Pumice Pumice is full of holes left behind as gases burst out of quickly cooling lava during an explosive eruption. Basalt (Giant s Causeway) The specimen is part of a thick lava flow that cooled and shrank to form hexagonal shapes, similar to the way cracks form in drying mud. The runny lava cooled quickly before crystals could form. 4 We live on Earth s crust. What do you notice about the crust s structure compared with the other layers that make up the planet? The crust is much thinner than the other layers. Although not a structural feature, students often also note that the crust is cooler, by interpreting the colours used for the layers of the model. Touch the meteorite next to the model Earth. As well as touching something from space, this is the closest you ll come to touching a piece of Earth s core. Why are iron meteorites useful for learning about Earth s core? It is made of the same material. Some students may explain that iron meteorites are thought to be fragments from the core of larger asteroids that were formed at the same time as Earth. Natural History Museum Explore and Discover 4

5 5 Choose either the Cynognathus skull, Glossopteris fossil or mesosaur fossil. On which continents has your fossil been found? Cynognathus skull: South America and Africa. Glossopteris fossil: South America, Africa, Australia, India and Antarctica. Mesosaur fossil: South America and Africa. What does your chosen fossil give evidence of? That the continents were once connected/joined together. IMPORTANT: Students choose EITHER 6a or 6b to answer. Please make sure students realise this. 6a Did you learn anything new from the quiz? Answers could include: Mountains form when continental crust meets continental crust. Oceanic crust is forced under continental crust when they meet. A rift valley forms when continental crust drifts from continental crust. New sea floor forms in the gap created when oceanic crust drifts from oceanic crust. The landscape shifts when continental crust rubs against continental crust. 6b Watch the tectonics film. What did you find most interesting? Students could include any of the information given about the structure of Earth, interactions between tectonic plates at their boundaries, and the impact of these interactions on landscape and people. 7 What are go-bags for? They provide everything you d need to survive if an earthquake strikes and you are left stranded. They are emergency kits. You have space to pack one thing in your go-bag. Decide what it would be and write it on the luggage label. Students often choose personal items such as photos and other treasured possessions. Discussions about the human experience of earthquakes can follow on from this question and from this display back at school. 8 Imagine you are a town councillor in an area prone to earthquakes. How would you try and reduce the impact of earthquakes on people? Write two ideas here: Ideas from the displays could include: Tsunami early warning systems, when the first seismic waves are detected. Automatic shutdowns of public transport and power stations in areas at risk of tsunamis, when the first seismic waves are detected. Build sea wall defences to protect towns and villages from tsunamis. Build defences against landslides, and avoid building houses near steep slopes or weak sediment. Don t build on clay-rich soil in earthquake-prone areas, to avoid the impact of liquefaction. Educate people that a large retreat of shoreline is the biggest indicator of a tsunami. To defend against fire after an earthquake, avoid using wood as a building material. Build earthquake-proofed buildings by making joints and materials more flexible, to absorb the vibrations. Natural History Museum Explore and Discover 5