Science Olympiad Dynamic Planet Practice Test

Which type of volcano is most likely to produce both explosive and non-explosive eruptions?

1. Cinder cone

2. Shield volcano

3. Composite volcano

4. Dormant volcano

The correct answer is: Composite volcano

Composite volcanoes, also known as stratovolcanoes, are characterized by their layered structure composed of both volcanic ash and lava flows. This construction allows them to produce a range of eruption styles, both explosive and non-explosive. The explosive nature is often due to the high viscosity of the magma, which can trap gases until pressure builds to a critical point, resulting in explosive eruptions. Conversely, when the magma in composite volcanoes is less viscous, it can flow more freely, leading to non-explosive eruptions. Cinder cone volcanoes typically produce relatively small eruptions primarily made up of pyroclastic material, which makes them less likely to exhibit both eruption styles. Shield volcanoes, with their broad, gently sloping sides and fluid lava flows, are predominantly associated with non-explosive eruptions. Dormant volcanoes simply refer to volcanoes that have not erupted in a long time but could accumulate any of the eruption characteristics when they become active again; however, they do not specifically define a type of eruption style. Thus, composite volcanoes are the ideal example of a type that can produce both explosive and non-explosive eruptions.