Grade 10 WEEK 5 ACTIVITY - CASE STUDY BASED ON RECENT EARTHQUAKES Use the information in your textbook to complete the task 1. What is the name of the area where all earthquakes are found around the world? 2. Give the names of the two plates that play a role in the Chile earthquakes. 3. Name the area below the surface of the Earth, where the earthquake originates. The earthquake of 2019 registered 6,8 on the Richter Scale in the 2019 earthquake. What is the 4. Richter Scale? Explain the role the Nazca plate plays in making the country highly prone to large magnitude 5. earthquakes. Briefly discuss how earthquakes impact humans with regard to; a) health 6. b) shortage of food c) destruction of property a) b) c) In a paragraph of approximately EIGHT lines explain strategies, by people, to reduce the impact 7. of earthquakes. WEEK 5 LESSON 9 GEOMORPHOLOGY: CASE STUDY BASED ON RECENT EARTHQUAKES Read the report with regard to earthquakes that occured in Chile in South America in 2010 and 2019. Answer the questions that follow. Chile is located on an active area known as the Ring of Fire, a horseshoe shaped area along the Pasific basin, in which around 90% of the world’s eartquakes and about 81% of the world’s largest earthquakes occur. Chile is largely located on the boarders of the Nazca plate and the continental South American plate. The subduction of the Nazca plate beneath the South American plate is causing high stress beneath Chile, making the country highly prone to large magnitude earthquakes. An earthquake struck the central coast of Chile on 29 September, 2019. This took place on or just above the subduction zone interface. The quake had a magnitude of 6.8 and was felt across central and south Chile. Chile’s National Emergency Office (CNEO) informed that there were no reports of injuries or deaths. No impact on the basic services or damage to infrastructure was done as was experienced during the massive earthquake on 27 February 2010 that registered 8.8 on the Richter scale. This triggered a tsunami that devasted coastal towns. Together, the earthquake and tsunami were responsible for more than 500 deaths. It destroyed 220000 homes and washed away docks, riverfronts and seaside resorts. The epicenter was approximately 70 km west-southwest of Constitución City (Talca Province), and 63 km north-west of Pelluhue Town (Cauquenes Province). Fault or fault scarp: The surface where the break occurs Focus: Place where earthquake starts below the surface of the earth Epicenter: Located directly above the focus on the surface of the earth VOLCANOES ACTIVITY: VOLCANOES What is a volcano? Distinguish between magma and lava. Magma: Lava: Where do we find volcanoes? Explain the difference between intrusive Intrusive volcanic features: and extrusive volcanic features. Also give examples of each. Extrusive volcanic features: Label the diagram. Match the term in column A with the Column A Column B description in column B. Only write the lava 1) Area where pipe opens on the surface appropriate number. crater 2) Molten material above the earth’s surface Column A Column B magma 3) Cracks through which magma rises to the lava earth’s surface crater volcanic vent 4) Molten material below the surface of the magma earth volcanic vent volcanic pipe 5) A circular depression in the ground caused volcanic pipe by volcanic activity. TOPIC: VOLCANOES What is it? Where is it? / Where is it found? A volcano is: Volcanoes occur: • a landform that builds up as a result of many eruptions. • At the plate boundaries of the earth • an opening in the earth’s crust through which molten rock, gases and • In long, narrow belts around the entire Pacific Ocean called the “Pacific Ring of Fire” rock fragments can erupt. • Along the length of the Atlantic Ocean What does it look like? • In three other locations in southern Europe, eastern Asia and centre of the Pacific Ocean The molten material is called: • Magma while it is still below the Earth’s surface. What does it look like? • Lava as soon as the molten rock reaches the surface. Intrusive rocks gases volcanic features: • When magma solidifies in spaces it intruded underneath the surface lava bombs e.g. batholiths, laccoliths, lopoliths, pipes, dykes, sills Extrusive lava volcanic features: crater • When magma rises through pipes to the earth’s surface where it solidifies e.g. cinder cones, shield volcanoes, composite mudflows volcanoes Vent- area where pipe opens onto the surface pipe Crater- deep hollow/circular depression caused by volcanic activity where some vents lie Materials ejected by volcanoes: • Solid material- ash, rock pieces, lava bombs magma • Fluid material – fluid lava, mud flows • Gases—steam, nitrogen, carbon dioxide, sulphur dioxide Three groups of volcanoes: • Active volcanoes- still erupt • Dormant volcanoes- shows no sign of activity, but can erupt again • Extinct volcanoes- not expected to erupt ever again Why is it there? Volcanoes develop when: • two plates move away from one another and magma rises to fill the space forming volcanoes on the earth’s surface. • the oceanic crust moves towards continental crust. Oceanic crust is forced downwards to form deep sea trenches. Continental crust moves upwards to form volcanic islands arcs. .