Rurutu
| Rurutu | ||
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| Waters | Pacific Ocean | |
| Archipelago | Austral Islands | |
| Geographical location | 22 ° 28 ′ S , 151 ° 20 ′ W | |
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| length | 10.4 km | |
| width | 3.5 km | |
| surface | 32.75 km² | |
| Highest elevation | Mont Taatioe 389 m |
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| Residents | 2322 (2012) 71 inhabitants / km² |
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| main place | Moerai | |
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Rurutu is the northernmost inhabited island of the Austral Islands in the Pacific Ocean and is 572 km from Papeete Tahiti . Only the uninhabited atoll Maria is further north.
geography
Politically, Rurutu belongs to the French overseas territory of French Polynesia and forms its own municipality of the same name . Rurutu was discovered by James Cook in 1769 on his first South Sea voyage.
The island, which is elongated in north-south direction, has an area of 32.75 km² and in Mont Taatioe reaches a height of 389 meters above sea level. Rurutu is an upscale atoll with an offshore reef and a completely dry lagoon .
More recently, Rurutu has also become known as a place for whale watching: humpback whales mate here between July and October close to the coast.
geology
Rurutu forms part of the volcanic lineament of the Austral Islands. The island was formed in the Miocene ( Serravallian ) around 13 million years ago as a volcano of the Macdonald hotspot , to which the seamount of the same name goes back. The underlying oceanic crust is 84 million years old and dates from the early Santonian .
In a first stage of development, which lasted until the early Tortonian 10.5 million years ago, the Seamount grew gradually. Initially, tholeiitic, alkali basaltic, picrobasaltic and Hawaiian pillow lavas poured into not too great a depth of water. After the island had appeared, the volcanism was alkali-rich and flowed subaerial alkali basalt - and Hawaiitlaven from which a shield volcano built. All older volcanic rocks are geochemically very rich in the radiogenic HIMU component of the earth's mantle . The HIMU component is viewed as an indicator of recycled oceanic crust and is characterized by very high 206 Pb / 204 Pb ratios, which can be explained by hydrothermal rubidium loss or the loss of rubidium and 204 Pb during partial melting during subduction.
In the next four million years (up to the Messinian 6.5 million years ago) a massive coral reef consisting of wackestone and packstone structures grew around the entire shield volcano .
About 1.1 million years ago ( Pleistocene ), Rurutu drifted over the Arago hotspot , which is now about 120 kilometers further south-east (the plate speed is 110 millimeters / year), in conjunction with the Pacific plate moving west-northwest . This raised the island and its fringing reef by 150 meters. Steep walls were created in the coral reef, which was also interspersed with karst caves rich in concretions .
Between 1.1 and 0.6 million years ago, the younger volcanic rocks poured out - very alkali-rich lava flows of Basanitic and Basanitic-Hawaiian composition.
geomorphology
Surf caves can be seen in the cliffs of the raised limestone walls . There are three levels:
- a recent surf platform
- a Middle Holocene surf cave with platform
- a surf cave of the last interglacial.
The recent surf cave is 2 to 3 meters high and is cut 3 to 6 meters into the rock. However, due to the rise in global sea levels , it is on the verge of destruction. The so-called Middle Holocene level, English mid-Holocene highstand or MHH for short , dates back to 2000 BC in the area of the Austral Islands . Until the year 0. The associated hollow is between + 1.2 and + 1.7 meters above the current sea level. The surf cave of the last interstadial (MIS 5), which is dated 118,000 to 126,000 years ago, follows at + 8 to + 10 meters.
There is a tropical cyclone hazard on Rurutu , as the Austral Islands are hit by cyclones every 6 to 7 years on average. For example, in 1991 the hurricane Wasa left a scree field of coral limestone blocks on the reef platform, which can still be seen today.
population
The 2322 inhabitants (as of 2012) are mainly spread over the three villages Moerai , Hauti and Avera . 2.5 km northeast of Moerai is the island's airport ( IATA : RUR, ICAO : NTAR). Since the visit of the French President François Mitterrand in 1990, tourism has developed significantly and has developed into an important industry alongside agriculture and fishing. The indigenous people of Rurutu were cave dwellers, unique in French Polynesia. The caves in the upscale coral ring - called makatea in Polynesia - and filled with concretions served as living quarters .
Traditional outline
Rurutu was traditionally divided into nine districts:
These are clockwise, starting in the northwest:
Map with all coordinates: OSM | WikiMap
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Individual evidence
- ↑ Evelpidou, N., Kampolis, I., Pirazzoli, PA and Vassilopoulos, A .: Global sea-level rise and the disappearance of tidal notches . In: Global Planetary Change . tape 92-93 , 2012, pp. 248-256 .
- ↑ Pirazzoli, PA and Salvat, B .: Ancient shorelines and Quaternary vertical movements on Rurutu and Tubuai (Austral Isles, French Polynesia) . In: Z. Geom. NF . tape 36 , 1992, pp. 431-451 .
- ↑ Caratéristiques des individus de Toute La Polynésie française Institut Statistique de Polynésie Française (ISPF) - Recensement de la population 2012 (French)
- ↑ Robert Bollt: Excavation in Peva Valley, Rurutu, Austral Islands (East Polynesia) . In: Asian Perspectives . tape 47 , no. 1 , 2008, p. 156–187, here p. 159 ( hawaii.edu [PDF; 13,9 MB ]).
- ↑ Robert Bollt: Recherche sur le site de Peva, Rurutu, Iles Australes. (PDF; 917 kB) pp. 202–208 , accessed on January 30, 2019 .
- ↑ Map of Rurutu with entries of all district names
- ^ Pierre Vérin: L'Ancienne Civilization de Rurutu. ORSTOM, Paris 1969 ( online )
literature
- Pierre Verin: L'Ancienne Civilization de Rurutu (îles Australes, Polynésie Française): la période classique . Paris 1969 (318 pages (with map on p. 24), ird.fr [PDF; accessed January 30, 2019]).
- Taaria Walker dite Pare, Rurutu, mémoires d'avenir d'une île australe , Rurutu, March 1999.
Web links
- Topographic map of Rurutu , Lemanotel.com
- Topographic map of Rurutu , Sea-Seek.com
- Tourist map of Rurutu , The Tahiti Traveler
