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72-684: The Diamantina Fracture Zone ( DFZ , Diamantina Zone ) is an area of the south-eastern Indian Ocean seafloor, consisting of a range of ridges and trenches. It lies to the south of the mideastern Indian Ocean features of the Wharton Basin and Perth Basin , and to the south west of the Naturaliste Plateau . Being parallel to the Southeast Indian Ridge , the Diamantina Fracture Zone is not

144-468: A global rise in sea level. Sea level also increases in the Indian Ocean, except in the south tropical Indian Ocean where it decreases, a pattern most likely caused by rising levels of greenhouse gases . Among the tropical oceans, the western Indian Ocean hosts one of the largest concentrations of phytoplankton blooms in summer, due to the strong monsoon winds. The monsoonal wind forcing leads to

216-451: A maximum width of 175 km (109 mi). The passive margins have an average width of 47.6 ± 0.8 km (29.58 ± 0.50 mi). The average width of the slopes (horizontal distance from shelf break to foot of slope) of the continental shelves are 50.4–52.4 km (31.3–32.6 mi) for active and passive margins respectively, with a maximum width of 205.3–255.2 km (127.6–158.6 mi). In correspondence of

288-549: A number of islands. These include those controlled by surrounding countries, and independent island states and territories. Of the non-coastal islands, there are two broad clusters: one around Madagascar, and one south of India. A few other oceanic islands are scattered elsewhere. In contrast to the Atlantic and Pacific, the Indian Ocean is enclosed by major landmasses and an archipelago on three sides and does not stretch from pole to pole, and can be likened to an embayed ocean. It

360-470: A period of six years, except for debris that gets indefinitely stuck in the centre of the gyre. The garbage patch in the Indian Ocean will, according to a 2012 study, decrease in size after several decades to vanish completely over centuries. Over several millennia, however, the global system of garbage patches will accumulate in the North Pacific. There are two amphidromes of opposite rotation in

432-790: A process of aridification began in the southwest Indian Ocean began around 4,000 years ago. Mammalian megafauna once widespread in the MPA was driven to near extinction in the early 20th century. Some species have been successfully recovered since then — the population of white rhinoceros ( Ceratotherium simum simum ) increased from less than 20 individuals in 1895 to more than 17,000 as of 2013. Other species still depend on fenced areas and management programs, including black rhinoceros ( Diceros bicornis minor ), African wild dog ( Lycaon pictus ), cheetah ( Acynonix jubatus ), elephant ( Loxodonta africana ), and lion ( Panthera leo ). This biodiversity hotspot (and namesake ecoregion and "Endemic Bird Area")

504-541: A range of 82 to 37 million years ago This age progression has led geologists to theorize that a hotspot in the mantle beneath the Indo-Australian Plate created the ridge as the plate has moved northward in the late Mesozoic and Cenozoic . This theory was supported by analysis of the chemistry of the Kerguelen Plateau and Rajmahal Traps , which were believed to represent

576-536: A significant garbage patch . Historically, the Indian Ocean has been a hub of cultural and commercial exchange since ancient times. It played a key role in early human migrations and the spread of civilizations. In modern times, it remains crucial for global trade, especially in oil and hydrocarbons. Environmental and geopolitical concerns in the region include the effects of climate change , piracy, and strategic disputes over island territories. The Indian Ocean has been known by its present name since at least 1515, when

648-464: A strong coastal and open ocean upwelling , which introduces nutrients into the upper zones where sufficient light is available for photosynthesis and phytoplankton production. These phytoplankton blooms support the marine ecosystem, as the base of the marine food web, and eventually the larger fish species. The Indian Ocean accounts for the second-largest share of the most economically valuable tuna catch. Its fish are of great and growing importance to

720-424: A subset of basalt which were shown to increase in age from approximately 43.2  ± 0.5 million years ago in the south to 81.8  ± 2.6 million years ago in the north. A more recent analysis using modern Ar–Ar techniques gives an age progression from 77  million years ago at 5°N to 43  million years ago at 31°S. Even more recent work with more samples gives

792-609: A true fracture zone in the sense used in plate tectonics , and includes an escarpment , separating two oceanic plateaus , being the southern border of the Broken Ridge Plateau . Its extension to the west is called the Diamantina Escarpment and the trench to the east of the escarpment the Diamantina Trench . All these features are mirrored by corresponding topography on the other side of

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864-473: Is a patchwork of small forested areas, often with a unique assemblage of species within each, located within 200 km (120 mi) from the coast and covering a total area of c. 6,200 km (2,400 sq mi). It also encompasses coastal islands, including Zanzibar and Pemba, and Mafia. This area, one of the only two hotspots that are entirely arid, includes the Ethiopian Highlands ,

936-513: Is centered on the Indian Peninsula. Although this subcontinent has played a significant role in its history, the Indian Ocean has foremostly been a cosmopolitan stage, interlinking diverse regions by innovations, trade, and religion since early in human history. The active margins of the Indian Ocean have an average width (horizontal distance from land to shelf break ) of 19 ± 0.61 km (11.81 ± 0.38 mi) with

1008-701: Is located between the Bay of Bengal and the Andaman Islands. In Indonesia, the so-called Indonesian Seaway is composed of the Malacca , Sunda and Torres Straits . The Gulf of Carpentaria is located on the Australian north coast while the Great Australian Bight constitutes a large part of its southern coast. Several features make the Indian Ocean unique. It constitutes the core of

1080-472: Is named after HMAS  Diamantina  (K377) , which conducted further exploration in 1961. Professor Alan Jamieson from The University of Western Australia led a scientific expedition to the eastern margin of the DFZ, which enters the southwest corner of the Australian exclusive economic zone. Professor Jamieson's team deployed baited landers beyond 6,000 m (20,000 ft) water depth aiming to document

1152-476: Is now named after India , which protrudes into it, and has been known by its current name since at least 1515. It is the only ocean named after a country. It has an average depth of 3,741 m. All of the Indian Ocean is in the Eastern Hemisphere . Unlike the Atlantic and Pacific, the Indian Ocean is bordered by landmasses and an archipelago on three sides, making it more like an embayed ocean centered on

1224-598: Is predominantly a historic divergent plate boundary with eruptives from a deep mantle source. The ridge has been surveyed several times in the past, including several times by the Deep Sea Drilling Program (DSDP). In 2007, the RV Roger Revelle collected bathymetric, magnetic and seismic data together with dredge samples from nine sites along the ridge as part of an Integrated Ocean Drilling Program (IODP) site survey intended to examine

1296-469: Is projected to push the tropical Indian Ocean into a basin-wide near-permanent heatwave state by the end of the 21st century, where marine heatwaves are projected to increase from 20 days per year (during 1970–2000) to 220–250 days per year. South of the Equator (20–5°S), the Indian Ocean is gaining heat from June to October, during the austral winter, while it is losing heat from November to March, during

1368-601: The Dordrecht Deep , within the axis of the fracture zone, with a maximum water depth of between 7,090 to 7,100 metres (23,260 to 23,290 ft). Based on this research, it was suggested that the Dordrecht Deep within the DFZ in the southeast Indian Ocean, and the Sunda Trench in the eastern Indian Ocean (~ 11°12′S 118°30′E  /  11.2°S 118.5°E  / -11.2; 118.5 ), are

1440-632: The East African Rift valley , the Socotra islands, as well as some small islands in the Red Sea and areas on the southern Arabic Peninsula. Endemic and threatened mammals include the dibatag ( Ammodorcas clarkei ) and Speke's gazelle ( Gazella spekei ); the Somali wild ass ( Equus africanus somaliensis ) and hamadryas baboon ( Papio hamadryas ). It also contains many reptiles. In Somalia,

1512-785: The International Hydrographic Organization in 1953 included the Southern Ocean but not the marginal seas along the northern rim but in 2002 the IHO delimited the Southern Ocean separately, which removed waters south of 60°s from the Indian Ocean but included the northern marginal seas. Meridionally , the Indian Ocean is delimited from the Atlantic Ocean by the 20° east meridian , running south from Cape Agulhas , South Africa, and from

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1584-818: The Mascarene Basin the CDW becomes a deep western boundary current before it is met by a re-circulated branch of itself, the North Indian Deep Water. This mixed water partly flows north into the Somali Basin whilst most of it flows clockwise in the Mascarene Basin where an oscillating flow is produced by Rossby waves . Water circulation in the Indian Ocean is dominated by the Subtropical Anticyclonic Gyre,

1656-513: The Shelf break , also known as Hinge zone, the Bouguer gravity ranges from 0 to 30 mGals that is unusual for a continental region of around 16 km thick sediments. It has been hypothesized that the "Hinge zone may represent the relict of continental and proto-oceanic crustal boundary formed during the rifting of India from Antarctica ." Australia, Indonesia, and India are the three countries with

1728-480: The Southeast Indian Ridge . The Broken Ridge Plateau has separated at the ridge from the Kerguelen Plateau and these were components of the Earth's second largest characterised large igneous province by volume. This formed between 136 and 124 million years ago and covered more than 244,000 km (94,000 sq mi). The Diamantina Fracture Zone was first detected by RV  Vema and RV Argo in 1960. It

1800-786: The Zambezi , Ganges - Brahmaputra , Indus , Jubba , and Murray rivers and (order 4) the Shatt al-Arab , Wadi Ad Dawasir (a dried-out river system on the Arabian Peninsula) and Limpopo rivers. After the breakup of East Gondwana and the formation of the Himalayas, the Ganges-Brahmaputra rivers flow into the world's largest delta known as the Bengal delta or Sunderbans . Marginal seas , gulfs, bays and straits of

1872-648: The flood basalts erupted at the initiation of volcanism at the Kerguelen hotspot which was then sheared in two as the Indian subcontinent moved northward. However the area of the Ninety East Ridge as well as being related to the hotspot was noted to be part of the diffuse boundary between the Indian Plate and Australian Plate . This has led to modifications of understanding. Some maintain close to

1944-642: The runoff water to the Indian Ocean. Mainly in summer, this runoff flows into the Arabian Sea but also south across the Equator where it mixes with fresher seawater from the Indonesian Throughflow . This mixed freshwater joins the South Equatorial Current in the southern tropical Indian Ocean. Sea surface salinity is highest (more than 36  PSU ) in the Arabian Sea because evaporation exceeds precipitation there. In

2016-612: The Arabian Sea, the violent Monsoon brings rain to the Indian subcontinent. In the southern hemisphere, the winds are generally milder, but summer storms near Mauritius can be severe. When the monsoon winds change, cyclones sometimes strike the shores of the Arabian Sea and the Bay of Bengal . Some 80% of the total annual rainfall in India occurs during summer and the region is so dependent on this rainfall that many civilisations perished when

2088-753: The Arabic Peninsula. Along the west coast of India, the Gulf of Kutch and Gulf of Khambat are located in Gujarat in the northern end while the Laccadive Sea separates the Maldives from the southern tip of India. The Bay of Bengal is off the east coast of India. The Gulf of Mannar and the Palk Strait separate Sri Lanka from India, while Adam's Bridge separates the two. The Andaman Sea

2160-581: The Comoros. Although both species represent an order of lobe-finned fishes known from the Early Devonian (410 mya ) and though extinct 66 mya, they are morphologically distinct from their Devonian ancestors. Over millions of years, coelacanths evolved to inhabit different environments — lungs adapted for shallow, brackish waters evolved into gills adapted for deep marine waters. Of Earth's 36 biodiversity hotspots nine (or 25%) are located on

2232-567: The DFZ has a depth of more than 5,800 m (19,000 ft). Later research using multibeam bathymetry data available from Geoscience Australia and the GMRT (Global Multi-Resolution Topography) Synthesis, infilled with data derived from the GEBCO_2014 global bathymetry dataset, suggested that the deepest point in the fracture zone would be at 33°27′07″S 101°28′05″E  /  33.452°S 101.468°E  / -33.452; 101.468 in

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2304-551: The East India Coastal Current to the Arabian Sea from January to April. An Indian Ocean garbage patch was discovered in 2010 covering at least 5 million square kilometres (1.9 million square miles). Riding the southern Indian Ocean Gyre , this vortex of plastic garbage constantly circulates the ocean from Australia to Africa, down the Mozambique Channel , and back to Australia in

2376-770: The Horn of Africa. The northern end of the Red Sea terminates in the Gulf of Aqaba and Gulf of Suez . The Indian Ocean is artificially connected to the Mediterranean Sea without ship lock through the Suez Canal , which is accessible via the Red Sea. The Arabian Sea is connected to the Persian Gulf by the Gulf of Oman and the Strait of Hormuz . In the Persian Gulf, the Gulf of Bahrain separates Qatar from

2448-891: The Indian Ocean Walker circulation there are no continuous equatorial easterlies. Upwelling occurs near the Horn of Africa and the Arabian Peninsula in the Northern Hemisphere and north of the trade winds in the Southern Hemisphere. The Indonesian Throughflow is a unique Equatorial connection to the Pacific. The climate north of the equator is affected by a monsoon climate. Strong north-east winds blow from October until April; from May until October south and west winds prevail. In

2520-712: The Indian Ocean include: Along the east coast of Africa, the Mozambique Channel separates Madagascar from mainland Africa, while the Sea of Zanj is located north of Madagascar. On the northern coast of the Arabian Sea , Gulf of Aden is connected to the Red Sea by the strait of Bab-el-Mandeb . In the Gulf of Aden, the Gulf of Tadjoura is located in Djibouti and the Guardafui Channel separates Socotra island from

2592-457: The Indian Ocean includes beaches and intertidal zones covering 3,000 km (1,200 sq mi) and 246 larger estuaries . Upwelling areas are small but important. The hypersaline salterns in India covers between 5,000–10,000 km (1,900–3,900 sq mi) and species adapted for this environment, such as Artemia salina and Dunaliella salina , are important to bird life. Coral reefs, sea grass beds, and mangrove forests are

2664-481: The Indian Ocean region, or almost half of the world's mangrove habitat, of which 42,500 km (16,400 sq mi) is located in Indonesia, or 50% of mangroves in the Indian Ocean. Mangroves originated in the Indian Ocean region and have adapted to a wide range of its habitats but it is also where it suffers its biggest loss of habitat. In 2016, six new animal species were identified at hydrothermal vents in

2736-730: The Indian Ocean, during the past six decades. The tuna catch rates have also declined 50–90% during the past half-century, mostly due to increased industrial fisheries, with the ocean warming adding further stress to the fish species. Endangered and vulnerable marine mammals and turtles: 80% of the Indian Ocean is open ocean and includes nine large marine ecosystems : the Agulhas Current , Somali Coastal Current , Red Sea , Arabian Sea , Bay of Bengal , Gulf of Thailand , West Central Australian Shelf , Northwest Australian Shelf and Southwest Australian Shelf . Coral reefs cover c. 200,000 km (77,000 sq mi). The coasts of

2808-432: The Indian Ocean, probably caused by Rossby wave propagation. Icebergs drift as far north as 55° south latitude , similar to the Pacific but less than in the Atlantic where icebergs reach up to 45°S. The volume of iceberg loss in the Indian Ocean between 2004 and 2012 was 24  Gt . Since the 1960s, anthropogenic warming of the global ocean combined with contributions of freshwater from retreating land ice causes

2880-466: The Indian Ocean. While the Indian Ocean warmed at a rate of 1.2°C per century during 1950–2020, climate models predict accelerated warming, at a rate of 1.7 °C–3.8 °C per century during 2020–2100. Though the warming is basin-wide, maximum warming is in the northwestern Indian Ocean including the Arabian Sea, and reduced warming off the Sumatra and Java coasts in the southeast Indian Ocean. Global warming

2952-466: The Indian Peninsula. Its coasts and shelves differ from other oceans, with distinct features, such as a narrower continental shelf . In terms of geology, the Indian Ocean is the youngest of the major oceans, with active spreading ridges and features like seamounts and ridges formed by hotspots . The climate of the Indian Ocean is characterized by monsoons . It is the warmest ocean, with a significant impact on global climate due to its interaction with

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3024-658: The Latin form Oceanus Orientalis Indicus ( lit.   ' Indian Eastern Ocean ' ) is attested, named after India, which projects into it. It was earlier known as the Eastern Ocean , a term that was still in use during the mid-18th century, as opposed to the Western Ocean ( Atlantic ) before the Pacific was surmised. In modern times, the name Afro-Asian Ocean has occasionally been used. The Hindi name for

3096-536: The Monsoon failed in the past. The huge variability in the Indian Summer Monsoon has also occurred pre-historically, with a strong, wet phase 33,500–32,500 BP; a weak, dry phase 26,000–23,500 BC; and a very weak phase 17,000–15,000 BP, corresponding to a series of dramatic global events: Bølling–Allerød warming , Heinrich , and Younger Dryas . The Indian Ocean is the warmest ocean in

3168-426: The Ocean is हिंद महासागर ( Hind Mahāsāgar ; lit. transl.  Ocean of India ). Conversely, Chinese explorers (e.g., Zheng He during the Ming dynasty ) who traveled to the Indian Ocean during the 15th century called it the Western Oceans. In Ancient Greek geography , the Indian Ocean region known to the Greeks was called the Erythraean Sea . The borders of the Indian Ocean , as delineated by

3240-450: The Pacific Ocean and half that of the Atlantic basin, or 30% of its ocean surface (compared to 15% for the Pacific). The Indian Ocean drainage basin is divided into roughly 800 individual basins, half that of the Pacific, of which 50% are located in Asia, 30% in Africa, and 20% in Australasia. The rivers of the Indian Ocean are shorter on average (740 km (460 mi)) than those of the other major oceans. The largest rivers are ( order 5 )

3312-415: The Pacific Ocean by the meridian of 146°49'E, running south from South East Cape on the island of Tasmania in Australia. The northernmost extent of the Indian Ocean (including marginal seas) is approximately 30° north in the Persian Gulf . The Indian Ocean covers 70,560,000 km (27,240,000 sq mi), including the Red Sea and the Persian Gulf but excluding the Southern Ocean, or 19.5% of

3384-441: The Southeast Arabian Sea salinity drops to less than 34 PSU. It is the lowest (c. 33 PSU) in the Bay of Bengal because of river runoff and precipitation. The Indonesian Throughflow and precipitation results in lower salinity (34 PSU) along the Sumatran west coast. Monsoonal variation results in eastward transportation of saltier water from the Arabian Sea to the Bay of Bengal from June to September and in westerly transport by

3456-411: The Southwest Indian Ridge, from where it continues into the Mozambique Channel and Prince Edward Fracture Zone . North of 20° south latitude the minimum surface temperature is 22 °C (72 °F), exceeding 28 °C (82 °F) to the east. Southward of 40° south latitude , temperatures drop quickly. The Bay of Bengal contributes more than half (2,950 km or 710 cu mi) of

3528-399: The Southwest Indian Ridge: a "Hoff" crab, a "giant peltospirid" snail, a whelk-like snail, a limpet, a scaleworm and a polychaete worm. The West Indian Ocean coelacanth was discovered in the Indian Ocean off South Africa in the 1930s and in the late 1990s another species, the Indonesian coelacanth , was discovered off Sulawesi Island , Indonesia. Most extant coelacanths have been found in

3600-440: The atmosphere. Its waters are affected by the Indian Ocean Walker circulation , resulting in unique oceanic currents and upwelling patterns. The Indian Ocean is ecologically diverse, with important marine life and ecosystems like coral reefs, mangroves, and sea grass beds. It hosts a significant portion of the world's tuna catch and is home to endangered marine species. It faces challenges like overfishing and pollution , including

3672-442: The austral summer. In 1999, the Indian Ocean Experiment showed that fossil fuel and biomass burning in South and Southeast Asia caused air pollution (also known as the Asian brown cloud ) that reach as far as the Intertropical Convergence Zone . This pollution has implications on both a local and global scale. Forty percent of the sediment of the Indian Ocean is found in the Indus and Ganges fans. The oceanic basins adjacent to

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3744-420: The biodiversity and geology of the region. Two hadal snailfish were captured during this voyage at 6,177 m (20,266 ft), both of which are believed to be new species. The first high-resolution multibeam bathymetry of the central DFZ was collected between June 2014 and June 2016, for the purpose of searching for Malaysia Airlines Flight 370 (MH370), which disappeared on 8 March 2014. This revealed that

3816-400: The bordering countries for domestic consumption and export. Fishing fleets from Russia, Japan, South Korea , and Taiwan also exploit the Indian Ocean, mainly for shrimp and tuna. Research indicates that increasing ocean temperatures are taking a toll on the marine ecosystem. A study on the phytoplankton changes in the Indian Ocean indicates a decline of up to 20% in the marine plankton in

3888-534: The centre of the 1,500,000 km (580,000 sq mi) hotspot, the landscape is dominated by Acacia - Commiphora deciduous bushland, but also includes the Yeheb nut ( Cordeauxia edulus ) and species discovered more recently such as the Somali cyclamen ( Cyclamen somalense ), the only cyclamen outside the Mediterranean. Warsangli linnet ( Carduelis johannis ) is an endemic bird found only in northern Somalia. An unstable political situation and mismanagement has resulted in overgrazing which has produced one of

3960-477: The continental slopes mostly contain terrigenous sediments. The ocean south of the polar front (roughly 50° south latitude ) is high in biologic productivity and dominated by non-stratified sediment composed mostly of siliceous oozes . Near the three major mid-ocean ridges the ocean floor is relatively young and therefore bare of sediment, except for the Southwest Indian Ridge due to its ultra-slow spreading rate. The ocean's currents are mainly controlled by

4032-537: The eastern extension of which is blocked by the Southeast Indian Ridge and the 90°E Ridge. Madagascar and the Southwest Indian Ridge separate three cells south of Madagascar and off South Africa. North Atlantic Deep Water reaches into the Indian Ocean south of Africa at a depth of 2,000–3,000 m (6,600–9,800 ft) and flows north along the eastern continental slope of Africa. Deeper than NADW, Antarctic Bottom Water flows from Enderby Basin to Agulhas Basin across deep channels (<4,000 m (13,000 ft)) in

4104-430: The hotspot hypothesis for the ridge. It had been assumed that India and Australia were on a single tectonic plate for at least the last 32 million years. However, considering the high level of large earthquakes in the Ninety East Ridge area and the evidence of deformation in the central Indian Ocean, it is more appropriate to consider the deformed region in the central Indian Ocean as a broad plate boundary zone separating

4176-436: The islands of the Indian Ocean are textbook cases of evolutionary processes; the dung beetles , day geckos , and lemurs are all examples of adaptive radiation . Many bones (250 bones per square metre) of recently extinct vertebrates have been found in the Mare aux Songes swamp in Mauritius, including bones of the Dodo bird ( Raphus cucullatus ) and Cylindraspis giant tortoise. An analysis of these remains suggests

4248-450: The large-scale Tropical Warm Pool which, when interacting with the atmosphere, affects the climate both regionally and globally. Asia blocks heat export and prevents the ventilation of the Indian Ocean thermocline . That continent also drives the Indian Ocean monsoon , the strongest on Earth, which causes large-scale seasonal variations in ocean currents, including the reversal of the Somali Current and Indian Monsoon Current . Because of

4320-427: The longest shorelines and exclusive economic zones . The continental shelf makes up 15% of the Indian Ocean. More than two billion people live in countries bordering the Indian Ocean, compared to 1.7 billion for the Atlantic and 2.7 billion for the Pacific (some countries border more than one ocean). The Indian Ocean drainage basin covers 21,100,000 km (8,100,000 sq mi), virtually identical to that of

4392-481: The margins of the Indian Ocean. The origin of this diversity is debated; the break-up of Gondwana can explain vicariance older than 100 mya, but the diversity on the younger, smaller islands must have required a Cenozoic dispersal from the rims of the Indian Ocean to the islands. A "reverse colonisation", from islands to continents, apparently occurred more recently; the chameleons , for example, first diversified on Madagascar and then colonised Africa. Several species on

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4464-400: The monsoon. Two large gyres , one in the northern hemisphere flowing clockwise and one south of the equator moving anticlockwise (including the Agulhas Current and Agulhas Return Current ), constitute the dominant flow pattern. During the winter monsoon (November–February), however, circulation is reversed north of 30°S and winds are weakened during winter and the transitional periods between

4536-438: The monsoons. The Indian Ocean contains the largest submarine fans of the world, the Bengal Fan and Indus Fan , and the largest areas of slope terraces and rift valleys . The inflow of deep water into the Indian Ocean is 11  Sv , most of which comes from the Circumpolar Deep Water (CDW). The CDW enters the Indian Ocean through the Crozet and Madagascar basins and crosses the Southwest Indian Ridge at 30°S. In

4608-435: The most degraded hotspots where only c. 5 % of the original habitat remains. Ninety East Ridge The ridge divides the Indian Ocean into the West and East Indian Ocean. The northeastern side is named the Wharton Basin and ceases at the western end of the Diamantina Fracture Zone which passes to the east and almost to the Australian continent. The ridge is primarily composed of Ocean Island Tholeiites (OIT),

4680-475: The most productive ecosystems of the Indian Ocean — coastal areas produce 20 tones of fish per square kilometre. These areas, however, are also being urbanised with populations often exceeding several thousand people per square kilometre and fishing techniques become more effective and often destructive beyond sustainable levels while the increase in sea surface temperature spreads coral bleaching. Mangroves covers 80,984 km (31,268 sq mi) in

4752-401: The original view. The Ninety East Ridge has no systematic isotopic variation observed along the ridge and this is inconsistent with the hypothesis of an ageing mantle plume origin for all of the ridge. At least three distinct sources must have contributed to the basalts of the ridge. This results in the interpretation that at least two separate hotspots contributed and the Ninety East Ridge

4824-447: The second deepest point after the Sunda Trench. The shallowest point in the area is the 1,125 m (3,691 ft) point in the Broken Ridge, close to Ninety East Ridge . 35°S 104°E  /  35°S 104°E  / -35; 104 Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering 70,560,000 km (27,240,000 sq mi) or approximately 20% of

4896-479: The two candidates for the deepest points in the Indian Ocean. To resolve this debate, the Diamantina Fracture Zone was surveyed by the Five Deeps Expedition in March 2019 by the Deep Submersible Support Vessel DSSV Pressure Drop , equipped with a full-ocean depth Kongsberg SIMRAD EM124 multibeam echosounder system. Using this echosounder and direct measurement by a Benthic lander , a maximum water depth of 7,019 m (23,028 ft) m ±17 m (56 ft)

4968-410: The water area of Earth's surface . It is bounded by Asia to the north, Africa to the west and Australia to the east. To the south it is bounded by the Southern Ocean , or Antarctica , depending on the definition in use. The Indian Ocean has large marginal, or regional seas, such as the Andaman Sea , the Arabian Sea , the Bay of Bengal , and the Laccadive Sea . Once called the Eastern Ocean, it

5040-426: The world's oceans; its volume is 264,000,000 km (63,000,000 cu mi) or 19.8% of the world's oceans' volume; it has an average depth of 3,741 m (12,274 ft) and a maximum depth of 7,290 m (23,920 ft). All of the Indian Ocean is in the Eastern Hemisphere and the centre of the Eastern Hemisphere, the 90th meridian east , passes through the Ninety East Ridge . Within these waters are

5112-417: The world. Long-term ocean temperature records show a rapid, continuous warming in the Indian Ocean, at about 1.2 °C (34.2 °F) (compared to 0.7 °C (33.3 °F) for the warm pool region) during 1901–2012. Research indicates that human induced greenhouse warming , and changes in the frequency and magnitude of El Niño (or the Indian Ocean Dipole ), events are a trigger to this strong warming in

5184-458: Was measured for the Dordrecht Deep, at 33°37′52″S 101°21′22″E  /  33.631°S 101.356°E  / -33.631; 101.356 , 167 m (548 ft) deeper than and ~30 km (19 mi) southwest of the Stewart and Jamieson (2019) GEBCO_14-derived location. This confirmed that the Diamantina Fracture Zone does not contain the deepest point in the Indian Ocean, but may be

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