 NASA image of Zavodovski Island (viewed at an angle from the north/northwest) | |
  Zavodovski Island Location in South Georgia and the South Sandwich Islands. | |
| Geography | |
|---|---|
| Location | Southern Ocean |
| Coordinates | 56°18′S27°35′W / 56.30°S 27.58°W /-56.30; -27.58[1] |
| Length | 4 km (2.5 mi) |
| Width | 3.8 km (2.36 mi) |
| Highest elevation | 551 m (1808 ft) |
| Highest point | Mount Curry |
| Administration | |
United Kingdom | |
| Demographics | |
| Population | uninhabited |
Zavodovski Island is an uninhabitedvolcanic island in theTraversay Islands subgroup of theSouth Sandwich Islands, which are located southeast ofSouth Georgia in theSouth Atlantic Ocean. Zavodovski is the northernmost of the South Sandwich Islands and consists of one majorstratovolcano, Mount Curry, which is surrounded to the east by a plain formed bylava flows. Mount Curry has afumarolically activecrater on the southwestern side, which also bears traces of asector collapse. An eruption occurred in 2016.
The island was officially discovered in December 1819 byThaddeus von Bellingshausen. The largestpenguin colony on Earth with over a million breeding pairs is situated on Zavodovski. It consists mostly ofchinstrap penguins, although other seabirds and penguin species breed on the island as well. Early explorers noted the bad smell of the island, which is reflected in numerous placenames.
Zavodovski is the northernmost of theSouth Sandwich Islands, which lie southeast ofSouth Georgia[2] in theSouthern Atlantic Ocean[3] and extend over a distance of 350 kilometres (220 mi) in north-south direction.[4] Together withLeskov andVisokoi Island, it makes up theTraversay Islands[5] subgroup of the South Sandwich Islands.[2] Politically, South Georgia and the South Sandwich Islands make up theUK Overseas Territory ofSouth Georgia and the South Sandwich Islands. In 2012, amarine protected area was established in the South Sandwich Islands. The scope of the protected area was further expanded in 2019.[6]Icebergs occur in the surrounding waters,[7] andsea ice reaches Zavodovski in August and September.[8]
The island has dimensions of 3.8 by 4.0 kilometres (2.4 mi × 2.5 mi)[9] and a diamond-shaped outline, with northern Reek Point, eastern Pungent Point, southern Fume Point and western Stench Point. Twoembayments are located north and northeast of Stench Point between theheadlands of Acrid Point and Pacific Point.[1] The coastlines are made up of 15–30 metres (49–98 ft) high cliffs, rock shelves and boulder beaches.[10] Slightly west of the centre of the island lies the 551 metres (1,808 ft)[11][1] or 557 metres (1,827 ft) high Mount Currystratovolcano, also known as Mount Asphyxia.[12] A volcanic crater lies on the southwestern flank,[1] and a further buried crater may exist northwest of the summit.[13] Twofumarolically active fissures extend eastward from Mount Curry to twoparasitic vents.[14]
The small size of the island prevents extensiveglaciation; there are only thin glaciers andsnow fields[15] (in 1962, ice area was about 0.1 square kilometres (0.04 sq mi)[16]) and ice is often ash-covered.[17] Except on the western side, wheremarine erosion has eroded away parts of the island,lava flows surround most of Mount Curry.[1] On the eastern side of the island, they form a gently undulating plain that is easily traversable[18] and accessible from the sea, by humans and penguins alike.[9] This asymmetry is probably due to the preferential emission of lava flows on the eastern side.[19] Lava flows featurecolumnar joints that are visible in coastal cliffs.[20] On the western side, cliffs show traces of asector collapse, which extended below sea level[21] and left a 4 cubic kilometres (0.96 cu mi) deposit on the seafloor.[22]
A 6 kilometres (3.7 mi) widesubmarine shelf surrounds Zavodovski at a depth of 70–160 metres (230–520 ft) on all sides except the western, where it has been removed by the sector collapse.[21] The shelf probably formed through marine erosion duringglacial sea level decrease.[23] The island lies on the western one of a pair of submarine ridges, which have a width of 54 kilometres (34 mi) at 1,800 metres (5,900 ft) depth[21] and form an edifice with a total volume of about 5,400 cubic kilometres (1,300 cu mi).[24] Their margins are cut bychutes andslump scars; the bathymetry is irregular.[25]Protector Shoal is 56 kilometres (35 mi) northwest of Zavodovski, and connected with it by asubmarine ridge at less than 1 kilometre (0.62 mi) depth.[26] In 1962, asubmarine eruption produced apumice raft that reached New Zealand.[27] Another, deeper, submarine ridge connects Zavodovski to Leskov Island to the southwest.[28]
East of the South Sandwich Islands, theSouth America Platesubducts beneath theScotia Plate at a rate of 70 millimetres per year (2.8 in/year). The subduction is responsible for the existence of the South Sandwichisland arc, which is constituted by about eleven islands[4] in an eastward curving chain,[29] andsubmarine volcanoes such as Protector in the north and Adventure andKemp in the south.[30] From north to south Zavodovski, Leskov Island, Visokoi Island,Candlemas Island-Vindication Island,Saunders Island,Montagu Island,Bristol Island-Freezland Rock,Bellingshausen Island,Cook Island-Thule Island emerge from the sea. Most of the islands are stratovolcanoes of various sizes.[26]
Basalt is the dominant rock produced by volcanic activity[31][21] and defines apotassium-poortholeiitic suite.[32]Phenocrysts includeaugite,clinopyroxene,olivine andplagioclase.[33] Compositional patterns at Zavodovski and Protector Shoal resemble those of Candlemas Island.[34] Intenseweathering gives the rocks yellow and red colours.[20]
Mosses grow on Zavodovski, andalgae in proximity to penguin colonies.[19] Unlike other islands in the South Sandwich Islands, vegetation is rare even around fumaroles.[35] It consists ofbryophytes.[36]Arthropods includemites.[37] At least one newbivalve species has been discovered at Zavodovski.[38]
Zavodovski has the largest population of breeding penguins on Earth.[39] 600,000–1,000,000chinstrap penguins breed on Zavodovski,[40] making up about one quarter of the global population of this species[41] and possibly one of the largestbird colonies in the world.[42] The colony is large enough to cause substantialammonia emissions in the region.[43] Other penguin species breeding on Zavodovski include more than 50,000macaroni penguins[40] which form small colonies within chinstrap penguin colonies,[44] andgentoo penguins. The size of the penguin colony on Zavodovski appears to be increasing.[45]King penguins also visit the island[46] and may breed there.[42][44] Otherseabirds breeding on Zavodovski includeAntarctic fulmars,Antarctic terns,black-bellied storm petrels,blue-eyed shags,cape petrels,kelp gulls,snow petrels,southern giant petrels andWilson's storm petrels.[40][47]Antarctic fur seal colonies occur along the coasts.[48]
Zavodovski has erupted during theHolocene,[31] though its rocks have not beenradiometrically dated. Alternating sequences oflava flows andtephra built the island up during the last few tens of thousands of years, and were more recently buried by ash fallout.[33] The eastern submarine ridge is covered by sediment and appears to be older, indicating that volcanism has moved westward over time.[49] Ifglaciers developed on Zavodovski during thelast glacial maximum, the steep submarine slopes would have restricted their expansion.[50]
The island is one of the most active volcanoes in the South Sandwich Islands.[51] It was reported to be smoking by von Bellingshausen, who observed emissions from the crater and noted a smell ofsulfur,[52] and there are frequent reports of steam emission.[9] Reports of eruptions in 1823, 1830 and 1908 may refer to fumarolic activity.[53] In 1830 fresh lava and floatingpumices were reported from the eastern side,[19] and a ship reported aneruption column in 1970.[9] In March 2016, an eruption produced a volcanic cloud and fallout of ash andlava bombs, covering parts of the island and leading the government of South Georgia to issue a navigation warning.[54] Reported inconsistencies of the height of Mount Curry may indicate volcanic activity that changed the summit elevation of the volcano.[15] Undamaged penguin bodies buried by volcanic ash have been found,[55] and activity may have obliterated breeding seabird colonies.[56]
Fumarolic activity occurs in the southwestern crater and extends to the cliffs on the sea, south of Acrid Point.[57] The fumarolic vents have deposited sulfur in the crater.[20] There are conflicting reports of emissions on the eastern and southern side of Zavodovski.[19] Volcanic heat is visible fromsatellite images,[9] and keeps certain parts of the island snow-free.[57] Emissions from Mount Curry alter the properties of clouds in the area, making them brighter.[58]
Seal hunters may have visited Zavodovski and the other Traversay Islands before 1819.[59] The official discovery was byThaddeus von Bellingshausen in December 1819. He sent a landing party ashore and named the island after the captain-lieutenant of his shipVostok.[5] The correct transliteration would be Zavadovskiy, but the older transliteration Zavadovski is the common one.[60] The Traversay Islands were named afterMarquis de Traversay who sponsored theBellingshausen expedition.[60] Other names of the island are Zawadowski, Ssawadowski, Sawadowsky and Prince Island.[61]
The South Sandwich Islands probably are not visited more frequently than a few times per year. Initially,sealers came to the islands, whilewhalers hunted in the surrounding seas. Scientific expeditions took place in 1930 and 1962.[26] Zavodovski is probably the most frequently visited of the South Sandwich Islands,[33] withcruise ships approaching to view the penguin colonies[62] and tourist boats landing.[63]
The South Sandwich Islands are uninhabited and remote; South Georgia is the closest inhabited place 250 kilometres (160 mi) northwest from Zavodovski.[26] Argentina installed theGuardiamarina Lamasbeacon on Zavodovski;[64] presently, anunmanned weather station on the island is operated by South Africa.[63] Politically, South Georgia and the South Sandwich Islands make up theUK Overseas Territory ofSouth Georgia and the South Sandwich Islands. In 2012, amarine protected area was established in the South Sandwich Islands. The scope of the protected area was further expanded in 2019.[6] Argentina had laid claim to the islands in 1957, in reaction to aSoviet landing on Zavodovski.[65]
Early discoverers remarked on the intense smell of the island,[66] which has been referred to as "the world's smelliest",[67] and numerous placenames on Zavodovski reference the smells and noxious fumes: Acrid Point, Fume Point, Noxious Bluff, Pungent Point, Reek Point and Stench Point.[a] Von Bellingshausen attributed it to penguin droppings, which forced his landing party to leave the island.[5] Noxious fumes also originate from the fumaroles.[19] The same odour may have poisonedCarl Anton Larsen during his 1908 visit[74] and forced him off the island.[75] Later reports noticed the smell several miles offshore.[19]
Capital:King Edward Point | |||||||
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| South Sandwich Islands |
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