Fig. 1 shows a simplified hazard map used by a planning team in the city of Padang, Indonesia. The map combines a coastal cross-section with the route of a ...
Question 1 Report
Fig. 1 shows a simplified hazard map used by a planning team in the city of Padang, Indonesia. The map combines a coastal cross-section with the route of a possible tsunami after a large earthquake beneath the Indian Ocean. Table 1 gives estimates collected during a school fieldwork study of how quickly water could reach different parts of the city. The team must decide where to improve evacuation routes and warning systems.
| Location | Distance inland from coast (km) | Estimated tsunami arrival time after warning (minutes) | Ground height above sea level (m) |
|---|---|---|---|
| Fishing harbour | 0.2 | 18 | 3 |
| Market district | 1.1 | 23 | 6 |
| Secondary school | 2.4 | 31 | 14 |
| Hill shelter | 3.0 | 36 | 38 |
(a) Outline two pieces of evidence from Fig. 1 and Table 1 which show why the fishing harbour is highly vulnerable to a tsunami. [4]
(b) Explain how an undersea earthquake can generate a tsunami. Use Fig. 1 in your answer. [6]
(c) Draw an annotated plan for a community tsunami-risk strategy for Padang. Your plan should include immediate warning, evacuation and longer-term methods to reduce the impacts of this natural hazard. [10]
Answer Details
(a) Any two developed observations: harbour is only 0.2 km inland [1]; it is only 3 m above sea level [1]; tsunami is estimated to arrive in 18 minutes [1]; this gives little time to evacuate / water can readily reach it [1]. [4] (b) Sudden movement on a destructive / subduction plate boundary displaces the sea floor [1]; a large volume of water is displaced vertically [1]; waves spread outwards across the ocean [1]; waves may be low in deep water [1]; in shallow coastal water they slow down [1]; wave height increases / water piles up and floods the coast [1]. [6] (c) Annotated plan, any ten from: seismic monitoring stations [1]; offshore buoys / tide gauges [1]; rapid official warning centre [1]; sirens [1]; phone alerts / radio messages [1]; clear signed evacuation routes [1]; regular drills in schools and neighbourhoods [1]; move to high ground such as the hill shelter [1]; purpose-built vertical evacuation towers [1]; raised shelters stocked with water and first aid [1]; prevent building in the lowest coastal zone [1]; strengthen coastal defences / maintain mangroves [1]; trained emergency teams [1]; maps showing safe areas [1]. [10]
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