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Definition and origin: many South Pacific islands are due to subduction
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{{Short description|Island of volcanic origin}}
{{Short description|Island of volcanic origin}}
{{For|places named High Island|High Island (disambiguation)}}
{{Redirect|High island|places named High Island|High Island (disambiguation)}}
{{Redirect|Volcanic Islands|the GPU series|AMD Radeon Rx 200 Series}}
{{For|the GPU series|Radeon 200 series{{!}}Volcanic Islands (GPU family)}}


[[File:Moorea ISS006.jpg|thumb|[[Moorea]], a ''high island'' of volcanic origin where the central island is still prominent]]
[[File:Moorea ISS006.jpg|thumb|[[Mo'orea]], a ''volcanic island'' where the central island is still prominent]]
[[File:DenglerSW-Stromboli-20040928-1230x800.jpg|thumb|[[Stromboli]] is one of the eight [[Aeolian Islands]], a [[volcanic arc]] north of [[Sicily]]]]
[[File:Aerial image of Stromboli (view from the northeast).jpg|thumb|[[Stromboli]] is one of the eight [[Aeolian Islands]], a [[volcanic arc]] north of [[Sicily]]]]


Geologically, a '''high island''' or '''volcanic island''' is an [[island]] of [[volcano|volcanic]] origin. The term can be used to distinguish such islands from [[low island]]s, which are formed from [[sedimentation]] or the [[Tectonic uplift|uplifting]] of [[coral reef]]s<ref>{{cite journal |first=Raymond E. |last=Murphy |jstor=210643 |title="High" and "Low" Islands in the Eastern Carolines |journal=[[Geographical Review]] |volume=39 |issue=3 |date=July 1949 |pages=425-439 |publisher=[[American Geographical Society]] |doi=10.2307/210643}}</ref> (which have often formed on sunken volcanos).
Geologically, a '''volcanic island''' is an [[island]] of [[volcano|volcanic]] origin. The term '''high island''' can be used to distinguish such islands from [[coral island|low islands]], which are formed from [[sedimentation]] or the [[Tectonic uplift|uplifting]] of [[coral reef]]s (which have often formed on sunken volcanos).<ref>{{cite journal |last=Murphy |first=Raymond E. |date=July 1949 |title="High" and "Low" Islands in the Eastern Carolines |journal=[[Geographical Review]] |publisher=[[American Geographical Society]] |volume=39 |issue=3 |pages=425–439 |bibcode=1949GeoRv..39..425M |doi=10.2307/210643 |jstor=210643}}</ref>


==Definition and origin==
==Definition and origin==
There are a number of "high islands" that rise no more than {{convert|1|m|0}} above [[sea level]], often classified as "[[islet]]s or rocks", while some low islands, such as [[Banaba]], [[Henderson Island (Pitcairn Islands)|Henderson Island]], [[Makatea]], [[Nauru]], and [[Niue]], as uplifted [[coral island]]s, rise over {{convert|50|m}} above sea level.
There are a number of volcanic islands that rise no more than {{convert|1|m|0}} above [[sea level]], often classified as [[islet]]s or rocks, while some low islands, such as [[Banaba]], [[Henderson Island (Pitcairn Islands)|Henderson Island]], [[Makatea]], [[Nauru]], and [[Niue]], rise over {{convert|50|m}} above sea level.


The two types of islands are often found in proximity to each other, especially among the [[list of islands in the Pacific Ocean|islands of the South Pacific Ocean]], where low islands are found on the [[fringing reef]]s that surround most high islands. Volcanic islands normally arise above a [[hotspot (geology)|hotspot]].
The two types of islands are often found in proximity to each other, especially among the [[list of islands in the Pacific Ocean|islands of the South Pacific Ocean]], where low islands are found on the [[fringing reef]]s that surround most volcanic islands. Volcanic islands normally rise above a [[hotspot (geology)|hotspot]] or [[subduction zone]].


==Habitability==
==Habitability==
High islands above a certain size usually have fresh [[groundwater]], while low islands often do not, so high islands are more likely to be habitable.
Volcanic islands usually range in size between {{convert|1|and|104|sqkm|sigfig=1}}.<ref>{{Citation |last=Condie |first=Kent C. |title=Chapter 2 – The crust |date=2022-01-01 |url=https://www.sciencedirect.com/science/article/pii/B9780128199145000111 |work=Earth as an Evolving Planetary System (Fourth Edition) |pages=9–37 |editor-last=Condie |editor-first=Kent C. |access-date=2023-12-28 |publisher=Academic Press |isbn=978-0-12-819914-5}}</ref> 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.<ref name=":0">{{Citation |last=Velmurugan |first=Ayyam |title=Chapter 1 – The Nature and Characters of Tropical Islands |date=2008-01-01 |url=https://www.sciencedirect.com/science/article/pii/B9780128130643000016 |work=Biodiversity and Climate Change Adaptation in Tropical Islands |pages=3–30 |editor-last=Sivaperuman |editor-first=Chandrakasan |access-date=2023-12-28 |publisher=Academic Press |isbn=978-0-12-813064-3 |editor2-last=Velmurugan |editor2-first=Ayyam |editor3-last=Singh |editor3-first=Awnindra Kumar |editor4-last=Jaisankar |editor4-first=Iyyappan}}</ref> 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.<ref name=":0" />

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.<ref>{{Cite journal |last1=López-Saavedra |first1=Marta |last2=Martí |first2=Joan |last3=Planagumà |first3=Llorenç |date= 2023|title=How Effective Risk Assessment and Management Is the Key to Turning Volcanic Islands into a Source of Nature-Based Solutions |journal=Land |language=en |volume=12 |issue=3 |pages=686 |doi=10.3390/land12030686 |doi-access=free |issn=2073-445X}}</ref>


==See also==
==See also==
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*{{annotated link|Archipelagic apron}}
*{{annotated link|Archipelagic apron}}
*{{annotated link|Atoll}}
*{{annotated link|Atoll}}
*{{annotated link|Canary Islands}}
*{{annotated link|Galápagos Islands}}
*{{annotated link|Galápagos Islands}}
*{{annotated link|Guyot}}
*{{annotated link|Guyot}}
*{{annotated link|Krakatoa Archipelago}}
*{{annotated link|Krakatoa Archipelago}}
*{{annotated link|Seamount}}
*{{annotated link|Seamount}}
*{{annotated link|Submarine landslide}}
*{{annotated link|Volcanic arc}}
*{{annotated link|Volcanic arc}}


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{{reflist}}
{{reflist}}


==External links==
== External links ==
*[http://www.britannica.com/EBchecked/topic/380461/Micronesian-culture/276610/High-island-and-low-island-cultures ''Micronesian culture: High island and low island cultures'' at Britannica.com.] Retrieved 2011-09-22.
* [http://www.britannica.com/EBchecked/topic/380461/Micronesian-culture/276610/High-island-and-low-island-cultures ''Micronesian culture: High island and low island cultures'' at Britannica.com.] Retrieved 2011-09-22.

{{DEFAULTSORT:High Island}}


{{Earth's landforms}}
{{Earth's landforms}}

Latest revision as of 07:07, 1 September 2024

Mo'orea, a volcanic island where the central island is still prominent
Stromboli is one of the eight Aeolian Islands, a volcanic arc north of Sicily

Geologically, a volcanic island is an island of volcanic origin. The term high island can be used to distinguish such islands from low islands, which are formed from sedimentation or the uplifting of coral reefs (which have often formed on sunken volcanos).[1]

Definition and origin

[edit]

There are a number of volcanic islands that rise no more than 1 metre (3 ft 3 in) 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 metres (160 ft) 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

[edit]

Volcanic islands usually range in size between 1 and 104 square kilometres (0.4 and 40 sq mi).[2] 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.[3] 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.[3]

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.[4]

See also

[edit]
  • Archipelagic apron – Fan-shaped gently sloping region of sea floor found around oceanic islands
  • Atoll – Ring-shaped coral reef
  • Canary Islands – Spanish archipelago and region in the Atlantic Ocean
  • Galápagos Islands – Ecuadorian archipelago and protected area
  • Guyot – Isolated, flat-topped underwater volcano mountain
  • Krakatoa Archipelago – Archipelago in the Sunda Strait, Indonesia
  • Seamount – Mountain rising from the ocean seafloor that does not reach to the water's surface
  • Submarine landslide – Landslides that transport sediment across the continental shelf and into the deep ocean
  • Volcanic arc – Chain of volcanoes formed above a subducting plate

References

[edit]
  1. ^ Murphy, Raymond E. (July 1949). ""High" and "Low" Islands in the Eastern Carolines". Geographical Review. 39 (3). American Geographical Society: 425–439. Bibcode:1949GeoRv..39..425M. doi:10.2307/210643. JSTOR 210643.
  2. ^ Condie, Kent C. (2022-01-01), Condie, Kent C. (ed.), "Chapter 2 – The crust", Earth as an Evolving Planetary System (Fourth Edition), Academic Press, pp. 9–37, ISBN 978-0-12-819914-5, retrieved 2023-12-28
  3. ^ a b Velmurugan, Ayyam (2008-01-01), Sivaperuman, Chandrakasan; Velmurugan, Ayyam; Singh, Awnindra Kumar; Jaisankar, Iyyappan (eds.), "Chapter 1 – The Nature and Characters of Tropical Islands", Biodiversity and Climate Change Adaptation in Tropical Islands, Academic Press, pp. 3–30, ISBN 978-0-12-813064-3, retrieved 2023-12-28
  4. ^ López-Saavedra, Marta; Martí, Joan; Planagumà, Llorenç (2023). "How Effective Risk Assessment and Management Is the Key to Turning Volcanic Islands into a Source of Nature-Based Solutions". Land. 12 (3): 686. doi:10.3390/land12030686. ISSN 2073-445X.
[edit]