Science Olympiad Dynamic Planet Practice Test

What causes earthquakes along divergent boundaries?

1. Plate pressuring

2. Seismic slip

3. Magma rise and solidification

4. Weathering effects

The correct answer is: Magma rise and solidification

Earthquakes along divergent boundaries are primarily caused by magma rise and solidification. At these boundaries, tectonic plates move apart from each other, creating a gap that allows magma from the mantle to rise towards the surface. As the magma ascends, it can create tension and stress within the surrounding rocks, leading to the fracturing of the crust. When the stress exceeds the strength of the rocks, it results in an earthquake. The solidification of this magma contributes to the formation of new crust, which is a fundamental process of sea-floor spreading found at mid-ocean ridges. This process is closely tied to the geological activity observed at divergent boundaries, reinforcing the relationship between magma movement and seismic activity. The other options do not sufficiently explain the cause of earthquakes in this context. Plate pressuring, for instance, involves more lateral compression seen at convergent boundaries rather than the tension seen at divergent boundaries. Seismic slip typically pertains to transform boundaries where two plates slide past one another. Weathering effects, while they can affect surface stability over time, do not directly lead to the seismic activity associated with divergent boundaries.