Describe the distribution of volcanoes shown in the map and identify anomalies to the patterns.

5% of all known volcanoes in the world are not located close to a plate margin. These are known as intraplate volcanoes and occur as a result of mantle plumes (aka hot spots).

Hotspots proposed to originate from the core-mantle boundary (red), the base of the upper mantle (yellow) and in the lithosphere (green). (Courtillot et al., 2003. Figure by G. Sella). So… mantle plumes can occur on plate margins e.g. Iceland or away from plate margins e.g. Hawaii

Mantle plumes / hotspots Video Animation

What are the possible origins of mantle plumes? Draw a diagram to show how island chains evolve over mantle plumes. Explain how island chains evolve over mantle plumes. Give specific details about the Hawaii including the nature of the volcanoes, development of the islands and how the evidence of the volcanic islands helps support the theory of plate tectonics. https://www.geolsoc.org.uk/Plate-Tectonics/Chap3-Plate-Margins/Mid-plate/Hawaiian-Islands

What are mantle plumes? Mantle plumes are caused by intensive radioactivity in the Earth’s core which creates a huge column of upwelling magma, known as a “plume”. The plume of plastic rock from the lower mantle pushes upwards; pressure drops and the plastic rocks become molten, melting and pushing through the crust above. This lies at a fixed position under the Tectonic Plate.  As the plate moves over the plume, the upwelling lava creates a steady succession of new volcanoes that migrate along with the plate.  The plume also eats into or melts the plate above, so that the thickness of the crust at this point is much smaller than the average. These domes or plumes of plastic rock can be up to 1,000 km across.

Hot spots What are mantle plumes? Example from Hawaii… Diagram explaining the formation of hot spots… Explanation of the features and landforms at hotspots