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Daily Prelims Practice Subject: Geography Topic: Geomorphology Batch: FEB 2021 Issue: Seismic Waves, Volcanoes

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Daily Prelims Practice Subject: Geography Topic: Geomorphology Batch: FEB 2021 Issue: Seismic Waves, Volcanoes Daily Prelims Practice Subject: Geography Topic: Geomorphology Batch: FEB 2021 Issue: Seismic waves, Volcanoes Date: 09/04/2021 6. Africa with the eastern Atlantic 1. SOLUTIONS floor plate 1. (b) Mt Stomboli 7. India-Australia-New Zealand plate Mount Stromboli has been in almost 2. Minor plates are continuous eruption for the past 2,000– 5,000 years, and its last serious one 1. Carribbean Plate occurred in 1921. A pattern of eruption 2. Cocos Plate is maintained in which explosions occur at the summit craters, with mild 3. Caroline Plate to moderate eruptions of incandescent 4. Juan de Fuca Plate volcanic bombs, a type of tephra, at 5. Juan Fernandez micro Plate intervals ranging from minutes to hour. 6. Iranian Plate The volcano has erupted many times 7. South sandwich Plate and is constantly active with minor 8. Myanmar Plate eruptions, often visible from many 9. Anatolian Plate points on the island and from the surrounding sea, giving rise to the 10. Nazca Plate island's nickname "Lighthouse of the 11. Nubian Plate Mediterranean" 12. Philippines Plate Mount Stromboli is an active volcano on a small island off the north 13. Okhotsk Plate coast of Sicily – one of three active 14. Scotian Plate volcanoes in Italy 15. Eastern micro Plate 2. (c) 2,3,4,6 only 16. Somalian Plate Earth is devided into 7 major and 17. Arabian Plate many minor plates. 18. Solomon Plate 7 major plates are 19. Fiji Plate 1. North American plate (with the western Atlantic floor separated 20. Bismarck Plate from the South American plate along the Caribbean islands) 3. (d) All the above. 2. South American plate (with The factors relating to the earth’s western Atlantic floor separated nature and its rotation include the from the North American plate gravitational force and deflective force along the Caribbean islands) by earth’s rotation also known as 3. Pacific plate Coriolis force. 4. Antarctica and the surrounding Oceanic factors include the pressure oceanic plate gradient, temperature variations and 5. Eurasia and the adjacent oceanic salinity differences. Ex-oceanic factors platee) are atmospheric pressure and winds, evaporation and precipitation. www.laexias.com Page 1 https://elearn.laex.in Daily Prelims Practice Subject: Geography Topic: Geomorphology Batch: FEB 2021 Issue: Seismic waves, Volcanoes Date: 09/04/2021 Tides caused by the gravitational pull Canary is a cold current off the coast of of the Moon and the Sun also play role South Africa in the forming of oceanic currents. Oyashio is a cold current off the west The factors that can modify the coast of Russia currents are direction and shape of coastlines, bottom reliefs of the ocean basins, seasonal variations and rotation of the earth. Ocean circulation is driven by winds and by differences in water density. Along with the winds, ocean currents distribute the tropical heat worldwide, thus they play a very important role in maintaining Earth’s heat balance. The density of the ocean water varies from place to place, a movement in the ocean waters occurs due to this. A gyre is any large system of rotating surface ocean currents, particularly those involved with large wind 6. (c) 1,2 and 3 only movements. Gyres are caused by the Coriolis Effect; planetary vorticity When a divergent boundary occurs along with horizontal and vertical beneath oceanic lithosphere, the rising friction, which determine the convection current below lifts the circulation patterns from the wind curl lithosphere, producing a mid-ocean (torque) ridge. Extensional forces stretch the lithosphere and produce a deep fissure. When the fissure opens, pressure is 4. (d) Neither 1 nor 2 reduced on the super-heated mantle At divergent boundaries, new crust is material below. It responds by melting, generated as the plates pull away from and the new magma flows into the each other. Mid ocean Atlantic ridge is fissure. The magma then solidifies and the best example divergent boundary the process repeats itself. At transform boundaries crust is The Mid-Atlantic Ridge is a classic neither created nor destroyed as the example of this type of plate boundary. plates slide horizontally past each other. Effects that are found at a divergent boundary between oceanic plates include: a submarine mountain range 5. (b) Kuroshio current. such as the Mid-Atlantic Ridge; Kuroshio is a warm current off the volcanic activity in the form of Japanese coast. fissure eruptions; shallow earthquake activity; creation of Benguela is a cold current off the coast new seafloor and a widening ocean of west Africa. basin. www.laexias.com Page 2 https://elearn.laex.in Daily Prelims Practice Subject: Geography Topic: Geomorphology Batch: FEB 2021 Issue: Seismic waves, Volcanoes Date: 09/04/2021 7. (c) 3 only Statement 2 is correct: Also, the Cocos plate:the Cocos Plate is a young rotation of the earth has its effect on oceanic tectonic plate beneath the the separated blocks of the plate Pacific Ocean off the west coast of portions. Central America, named for Cocos Island, which rides upon it. 10. (c) 2 and 3 only Nazca plate: The Nazca Plate, which Statement 1 is incorrect: Where underlies most of the southeastern new crust is generated as the plates Pacific, is being subducted beneath pull away from each other in most of the west coast of South divergent boundaries. Where the America at a rapid rate of 80 to 100 crust is destroyed as one plate millimetres per year. dived under another in convergent Nubia plate: the Nubian plate is a boundaries. There are three ways in geographically large area and which convergence can occur. These encompasses the North West region of are: (i) between an oceanic and the African continent and a large continental plate; (ii) between two chunk of the Atlantic Ocean oceanic plates; and (iii) between two continental plates. 8. (b) 1,3 and 4 only Statement 2 is correct: Continent- A convergent boundary is an area on Continent Convergent boundaries will Earth where two or more lithospheric result in formation of Fold mountains, plates collide. One plate eventually Volcanic activities. slides beneath the other causing a process known as subduction. The Statement 3 is correct: San Andres subduction zone can be defined by a fault is the result of Ocean-Continent plane where many earthquakes occur transform boundary between Juan de due to destruction of existing crust fuca and North American plate. called the Benioff Zone Ocean crust is denser than Continental crust. Plate with large area of Ocean will be the subducting plate since Ocean plates are denser. Ocean- Ocean convergent boundary result is formation of Islands, explosive volcanism and earthquakes. 9. (b)2 only Statement 1 is incorrect: As the eruptions do not take all along the entire crest of the plate at the same time, there is a differential movement of a portion of the plate away from the axis of the earth. www.laexias.com Page 3 https://elearn.laex.in .
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