Analysis of Geological Events

The correct answer is option A. C) Subduction zones.

1. The Determining Geological Factor: The Position of the Tectonic Plates

The main reason for the difference in magnitude between the reported earthquakes is the location of each city in relation to the tectonic plate boundariesThe Earth is covered by plates that are constantly in motion. The strongest and most frequent earthquakes occur at the boundaries where these plates meet and interact.

2. Analysis of Each Location

• Chile (Text I): The city of Valparaíso is located on the west coast of South America, precisely on the edge of the South American Plate, where the Nazca Plate It dives beneath it. This meeting point is called subduction zoneThe friction and immense pressure generated in this process accumulate a huge amount of energy, which, when released, causes high-magnitude earthquakes (like the one of magnitude 5.9).

• Amazonas (Text II): Although the state of Amazonas is located inland, it still feels the effects of activity at the edge of the tectonic plate. The text itself mentions that the tremors are a result of "Nazca Plate activity." The pressure generated in the subduction zone propagates through the interior of the South American Plate, causing tremors of medium magnitude (such as the 4.8 magnitude one) in areas with geological faults.

• São Paulo (Text III): The state of São Paulo is located in the center of the South American Plate, an area considered tectonically stable, far from the plate boundaries and subduction zones. The tremors that occur there are called "intraplate." They are caused by the release of accumulated stress in ancient geological faults and are characteristically of low magnitude (such as 3.0), rarely causing damage.

3. Evaluation of Other Alternatives

• A) Coastal plains, B) Continental basins, D) Denudation zones, E) Steep slopes: All of these options describe landforms or surface (geomorphological) processes. They are not the primary causes of earthquakes of tectonic origin, which are generated deep within the Earth's crust by the movement of tectonic plates.

4. Conclusion

The difference in earthquake intensity stems directly from each city's geographical position relative to the subduction zone between the Nazca and South American plates. Chile, being on the edge, experiences the strongest tremors; the Amazon, being further inland, experiences tremors of medium intensity; and São Paulo, being in the stable center of the plate, experiences only weak tremors.