The Tectonic Cycle Examine how the tectonic cycle helps to explain the global distribution of one of the following: • Volcanoes • Earthquakes • Fold Mountains. - Leaving Cert Geography - Question C - 2017

The tectonic cycle is fundamental in explaining the global distribution of volcanoes. Volcanoes are primarily located along tectonic plate boundaries, particularly at convergent and divergent boundaries.

1. Divergent Boundaries: At divergent boundaries, tectonic plates move away from each other. This movement allows magma from the mantle to rise and fill the gap, leading to the formation of new crust and consequently, volcanic activity. Notable examples include the Mid-Atlantic Ridge, where volcanic activity is frequent as new oceanic crust is formed.

2. Convergent Boundaries: In contrast, at convergent boundaries, one tectonic plate is forced beneath another in a process called subduction. This process leads to the melting of the subducted plate and the formation of magma, which can lead to explosive volcanic eruptions. The Pacific Ring of Fire is a prime example where numerous volcanoes are found due to this tectonic activity.

3. Hotspots: Additionally, volcanic activity can occur away from plate boundaries at hotspots, where plumes of hot mantle material rise to create volcanoes. The Hawaiian Islands are formed from such hotspots, showcasing a different aspect of the tectonic cycle.

In summary, the tectonic cycle directly influences the location and type of volcanic activity around the globe through mechanisms associated with plate movements at both divergent and convergent boundaries.