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WJEC – Geology of the Human Environment (GL3) – Jan 2004 1. Figure 1 is a map of Heimaey, a volcanic island to the south of Iceland. It shows the impact of the 1973 eruption on the fishing port of Vestmannaeyjar. Adapted from “Volcanoes” Alwyn Scarth Figure 1 (a) (i) Account for the presence of volcanic activity in this area with reference to the island’s plate tectonic situation. [2] …………………...……………………………………………………………………………… ………………………………………………………………………………………………...… …………………………………………………………………………………………………... (ii) State the type of lava most commonly erupted from volcanoes in this situation. [1] …………………………………………………………………………………………………... (b) (i) Describe two hazards that may have been associated with the tephra fall. [2] 1 ……………….………………………………………………………………………………... …………………………………………………………………………………………………... 2 ………………….…………………………………………………………………………...… …………………………………………………………………………………………………... (ii) Suggest two factors responsible for the distribution and thickness of the tephra shown on Figure 1. [2] 1 ……………….………………………………………………………………………………... …………………………………………………………………………………………………... 2 ………………….…………………………………………………………………………...… …………………………………………………………………………………………………... (c) Explain how spraying with seawater affected the flow of lava. [3] …………………………………………………………………………………………………... …………………………………………………………………………………………………... ………………………………………………………………………………………………….. ………………………………………………………………………………………………...… …………………………………………………………………………………………………... (d) Describe three possible advantages for the local population of living in a volcanic area. [3] 1………………………………………………………………………………………………... ………………………………………………………………………………………………...… 2……………………………………………………………………………………………….. ………………………………………………………………………………………………...… 3………………………………………………………………………………………………... …………………………………………………………………………………………………... Total 13 marks Notes for answers These represent suggested answers and do not necessarily represent all the possible acceptable alternatives of a mark scheme. Question 1 (a) (b) (i) Constructive/divergent boundary/Mid Atlantic Ridge Rising convection currents/magma Partial melting of mantle/ocean crust (2 max) [2] (ii) Mafic/basaltic [1] (i) Burial/collapsed buildings/infrastructure/with weight Fire from the hot tephra Destruction/damage from direct hit with bombs Respiratory/machinery problems from fine ash Other relevant hazards – effect on farming/fishing/vision Hazards by association – Gas/lahar/pyroclasic flows Must be described. (2 max) [2] Distance from the volcanic vent Direction/strength of the prevailing wind Effect of blast energy/direction Particle size/weight (2 max) [2] Lava cools rapidly/temperature drops Solidifies/crystallises Becomes more viscous Flows slower/stops/changes course (3 max) [3] New land Fertile volcanic soil Thermal energy source Improved harbour Tourism Building materials Other sensible – Mineral water/deposits (3 max) [3] (ii) (c) (d) Total 13 marks ESTA would like to thank the WJEC for allowing this question to be published on GEOTREX. Any comments should be directed to the Subject Officer for Geology at the WJEC. 15/04/2007
