Science Olympiad Dynamic Planet Practice Test

Which definition correctly describes hotspots?

1. Underwater volcanic regions at tectonic boundaries

2. Volcanic areas fed by abnormally hot mantle

3. Regions with no volcanic activity

4. All types of rift valleys

The correct answer is: Volcanic areas fed by abnormally hot mantle

Hotspots refer to volcanic regions that are fed by unusually hot material rising from deep within the Earth's mantle. This results in volcanic activity that is not necessarily associated with tectonic plate boundaries, unlike most volcanic activity that occurs primarily at these boundaries. The mantle plume, which is the source of the hot material, remains stationary while the tectonic plates move over it, leading to the formation of volcanic islands or chains, such as the Hawaiian Islands. The other options describe different geological phenomena or processes that do not fit the definition of hotspots. For example, underwater volcanic regions at tectonic boundaries typically refer to different types of volcanic activity associated with mid-ocean ridges or subduction zones. Regions with no volcanic activity would not qualify as hotspots at all, as hotspots are characterized by their volcanic nature. Lastly, rift valleys represent specific geological settings related to tectonic divergence and are not directly relevant to the concept of hotspots. Therefore, the definition given by the correct choice accurately encapsulates the essential characteristics and processes associated with hotspots.