Volcanic island

Definition and origin

There are a number of volcanic islands that rise no more than 1 m above sea level, often classified as islets or rocks, while some low islands, such as Banaba, Henderson Island, Makatea, Nauru, and Niue, rise over 50 m above sea level.

The two types of islands are often found in proximity to each other, especially among the islands of the South Pacific Ocean, where low islands are found on the fringing reefs that surround most volcanic islands. Volcanic islands normally rise above a hotspot or subduction zone.

Habitability

Volcanic islands usually range in size between 1 and. Islands above a certain size usually have fresh groundwater, while low islands often do not, so volcanic islands are more likely to be habitable.

Many volcanic islands emerge from the deep abyss of the ocean, and feature rough or mountainous landscapes in their interiors and a diverse array of summit elevations. Researchers have observed that the island will often be covered by dense tropical forest. These limit settlement on the interior of many islands, forcing communities to develop along the coast. Larger islands may have rivers, resulting in flood hazards. Rivers deliver sediment downstream, which can dominate the shape of the coast and contribute to erosion. Tall volcanic islands are often surrounded by protective fringing or barrier reefs, creating lagoons.

The unique geological and geographical characteristics of volcanic islands make them prone to many natural hazards, which are expected to worsen due to climate change. These include volcanic eruptions, earthquakes, tsunamis, landslides, and severe weather events like hurricanes or typhoons. Studies have highlighted the importance of implementing effective risk mitigation plans that include nature-based solutions to improve societal safety on these islands. These involve leveraging natural processes and ecosystems to reduce hazard impacts. This can include the restoration of natural barriers like mangroves or coral reefs that protect against tsunamis and storm surges or the maintenance of natural water catchments that can mitigate flood risks.

References

References

1. Murphy, Raymond E.. (July 1949). ""High" and "Low" Islands in the Eastern Carolines". [[American Geographical Society]].
2. Condie, Kent C.. (2022-01-01). "Chapter 2 – The crust". Academic Press.
3. Velmurugan, Ayyam. (2008-01-01). "Chapter 1 – The Nature and Characters of Tropical Islands". Academic Press.
4. (2023). "How Effective Risk Assessment and Management Is the Key to Turning Volcanic Islands into a Source of Nature-Based Solutions". Land.