Science Olympiad Dynamic Planet Practice Test

What type of volcanic eruption primarily happens through a linear vent?

1. Explosive eruptions

2. Fissure eruptions

3. Submarine eruptions

4. Effusive eruptions forming lava domes

The correct answer is: Fissure eruptions

Fissure eruptions primarily occur through linear vents, which are long cracks in the Earth's surface from which magma can flow. During a fissure eruption, magma rises from deep within the Earth and escapes through these linear openings instead of a single, central vent, leading to a more extensive and horizontal flow of lava. This type of eruption tends to produce large volumes of basaltic lava that can spread out over vast distances, creating extensive lava plateaus and low-lying land forms. The geological mechanics behind fissure eruptions contrast with other types, such as explosive eruptions, which typically occur from a single volcanic vent and are characterized by significant pressure buildup that results in violent eruptions. Effusive eruptions forming lava domes are associated with the buildup of viscous lava, which tends to be emitted from a central vent and forms a dome shape rather than spreading through a fissure. Submarine eruptions occur underwater and, while they can also involve fissure-like openings, the context of the question specifies "primarily," making fissure eruptions the most accurate choice for linear vent activity.