Question 1 Report
The table below shows earthquake-monitoring data from a plate-boundary study in southern Chile. Fig. 1 shows the positions of an oceanic plate and a continental plate beneath the Andes. The monitoring centre issued a public bulletin after several small earthquakes were detected close to the coast. Students are using the study figure to consider why this region experiences frequent tectonic hazards.
| Monitoring station | Distance from coast (km) | Number of earthquakes in one week | Greatest recorded magnitude |
|---|---|---|---|
| A | 12 | 17 | 4.1 |
| B | 58 | 9 | 3.6 |
| C | 126 | 3 | 2.8 |
(a) Which station recorded the greatest earthquake magnitude? [2]
(b) Outline why earthquakes occur at destructive plate margins. [2]
(c) Draw an annotated cross-section showing how Chile can reduce risk from earthquake shaking in a coastal city. [4]
(a) Station A [1]; magnitude 4.1 [1]. [2] (b) Plates move towards each other / one subducts [1]; friction causes stress to build and sudden release produces seismic waves [1]. [2] (c) Four annotations, one mark each: reinforced flexible building frames [1]; strict building-code inspections [1]; emergency open spaces / assembly areas [1]; automatic gas and electricity shut-off [1]; earthquake drills [1]; secure heavy furniture [1]; early warning linked to public alerts [1]. [4]
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