Indian Ocean and its straits. largest seas

INDIAN OCEAN

Indian Ocean the third largest water area in the world with an area of ​​76.17 million square meters. km, located between Africa in the west, Australia and the Sunda Islands in the east, Asia in the north and Antarctica in the south.

Straits of the Indian Ocean.

Straits– narrow bodies of water, dividing land areas and connecting neighboring seas or oceans.

1. Bab el-Mandeb Strait(Bab el-Mandeb - "gate of tears (sorrow)") - strait between the southwestern tipArabian Peninsula(the state of Yemen) and Africa (the states of Djibouti and Eritrea). Connects the Red Sea with Gulf of AdenArabian Sea.

The smallest width is 26.5 km, the smallest depth is fairway 182 m. Perim Island divided into 2 passages - Big (25 km wide, also known as Dakt el Mayun) and Small (3 km wide, also known as Bab-Iskander- Strait of Alexander). There is also a group of small islands off the African coast known as the Seven Brothers.

currents in the strait: in winter - the surface, carrying less salty water, is directed to the Red Sea, and the deep, with more salty water - from the Red Sea. In summer, the runoff of salt water from the Red Sea is carried out by the surface current (depth up to 25-50 m) and the bottom current (from 100-150 m to the bottom), the inflow of water into the Red Sea - by the intermediate current (depth from 25-50 m to 100-150 m). m).

The name of the strait is associated with the danger of navigation through it. There is an Arabic legend that claims that the origin of the name is associated with destructive earthquake that took place in the area in antiquity.

The strait has a large economic and strategic value, since the path from Europe to East and South Asia, as well as Australia.

2. Bali Strait ( indon. Selat Bali), Also Strait of Bali - strait in the waters Malay Archipelago between the Indonesian islands of Java and Bali . Connects water areas the seas of Bali, the Pacific Ocean (in the north) and indian ocean(in the south), passing between the eastern tip of Java and the western tip of Bali. The minimum width is about 2.4 km, the maximum depth is about 60 m.

Is a natural boundary between Java, belonging to the groupGreater Sunda Islands, and a group Lesser Sunda Islands(Bali, Lombok, Sumba, Sumbawa, Flores, Timor and etc.). It also passes the administrative border between the Indonesian provinces. East Java and Bali.

The main oceanological indicators of the strait are identical or close to those of the adjacent areas of the Bali Sea and the Indian Ocean. Water temperature around 27-28°C practically not subject to seasonal fluctuations. Salinity is about 33.0-34.0‰ . Small rivers flowing into the strait from both sides cause only minor, local desalination.

The ecological situation in the strait is relatively favorable, primarily due to the absence of large industrial facilities on the shores. On the Bali coast there is a national park "Western Bali", which includes more than 34 km² of the water area of ​​the strait.

Bali Strait - an area of ​​heavy traffic for small and medium-sized vessels

Navigation in the strait is quite active, but its capabilities are limited by relatively shallow depths - ocean-going vessels with deep draft do not enter here, using Bali to Indian Ocean deeper and widerLombok Strait.

3. Bass Strait - a strait separating Australia and the island of Tasmania and connecting the Indian Ocean with the Pacific.

The length is 490 m, the smallest width is 213 m, the depth of the navigable part is more than 51 m. In the western part - about. King, in the east - the islands of Furno. The current has a constant direction from West to East. The tides are semidiurnal, 1–2 m. Offshore oil fields are being developed. Port Melbourne ( Australia).

The strait is named by its discovererMatthew Flindersin honor of the ship physician George Bass in 1798.

4. Strait of the Eighth Degree - strait in Indian Oceanbetween the archipelagoLaccadive Islands(Minicoy Island) in the north and Maldivesin the south (under 8 ° north latitude). connectsLaccadive Seawith the main water areaindian ocean. The width is about 150 km.

On French maps, the strait was previously indicated as Courant de Malicut, on Dhivehi the strait is called Maliku-Kandu.

5. Gubal - strait between Sinai Peninsulaand large coral reefs red sea , northwest of Cape Ras Mohammed . It is characterized by relatively shallow depths (up to 40-50 m), medium currents, as well as a sparsely populated coastline covered with medium-altitude mountains.

6. Strait of the ninth degree- a strait in the Indian Ocean, in the southern part of the Laccadive Islands archipelago, between about. Minicoy and other small islands of the archipelago (at 9 ° north latitude). One of the straits connecting the Arabian and Laccadive Seas. Width about 100 km. Depths up to 2597 m.

7. Strait of the Tenth Degree ( English Ten Degree Channel) - strait inIndian Ocean. Passes along 10 ° north latitude, from which it got its name. separatesAndaman Islands(about. Small Andaman) from Nicobar Islands(Fr. Car Nicobar) and connects andaman sea With Bay of Bengal. The width is about 140 km. Depths up to 1500 m.

8. Sunda Strait ( indon. Selat Sunda, sun. Selat Sunda listen)) is a strait that separates the islands of Java and Sumatra and connects the Indian Ocean with the Java Sea of ​​the Pacific Ocean.

There are many in the strait volcanic islands origin, the most famous are the islands Krakatau, whose volcanic eruption in 1883 considered one of the most powerful in modern history.

Sunda Strait in northeast parts has a width of about 24 km and a depth of only about 20 m , which creates a problem for large courts. Especially large ships (for example, tankers) make a "hook » bypassing the islands.

The length of the strait is about 130 km, the tides are up to 1.5 m.

9. Duncan Strait- a strait in the Indian Ocean, about 48 km wide, dividing the island Rutland, Great Andaman , in the north and the island Small Andaman , on South. In the west, the strait opens intobay of bengal, in the east at andaman sea.

Several small islands lie along the entire strait.

From north to south they are:

Five Islands, popular place diving; the Manners Strait runs between the northern island of the Five and the island Rutland

Passage Island

sisters

North Brother

South Brother

10. Lombok Strait ( indon. Selat Lombok), Also strait of lombok - strait in the waters Malay Archipelago between the Indonesian islands of Bali and Nusa Penida (west side) and Lombok (from the east side).

Connects water areas the seas of Bali, the Pacific Ocean (in the north) and indian ocean(on South). In the southwestern part of the strait, its water area merges with the water area Badung Strait passing between the islands of Bali and Nusa Penida.

The minimum width is about 18 km - between the eastern tip of Nusa Penida and the southwestern tip of Lombok. The maximum depth is about 1400 m (in the northern part of the strait). The minimum depth along the fairway is at least 250 m.

The strait is the administrative border between the Indonesian provinces. Bali and Western Lesser Sunda Islands.

The largest settlements on the Bali coast Manggis and Kubu, in Lombok - Mataram (the main city of the island and the capital of the province of Western Lesser Sunda Islands) and Lembar . Often, Bali is referred to the ports of the Lombok Strait Padang Bay , which is actually located on the shores of the Badung Strait.

INDIAN OCEAN, the third largest ocean on Earth (after the Pacific and Atlantic), part of the World Ocean. Located between Africa in the northwest, Asia in the north, Australia in the east and Antarctica in the south.

Physical-geographical sketch

General information. The border of the Indian Ocean in the west (with the Atlantic Ocean south of Africa) is drawn along the meridian of Cape Agulhas (20 ° east longitude) to the coast of Antarctica (Queen Maud Land), in the east (with the Pacific Ocean south of Australia) - along the eastern border of the Bass Strait to the island of Tasmania , and then along the meridian 146 ° 55' east longitude to Antarctica, in the northeast (with the Pacific basin) - between the Andaman Sea and the Strait of Malacca, further along the southwestern shores of the island of Sumatra, the Sunda Strait, the southern coast of the island of Java, the southern the borders of the seas of Bali and Sava, northern border Arafura Sea, the southwestern coast of New Guinea and the western border of the Torres Strait. The southern high-latitude part of the Indian Ocean is sometimes referred to as the Southern Ocean, which combines the Antarctic sectors of the Atlantic, Indian, and Pacific oceans. However, such geographical nomenclature is not universally recognized, and, as a rule, the Indian Ocean is considered within its usual boundaries. The Indian Ocean is the only one of the oceans that is located mostly in the Southern Hemisphere and is limited in the north by a powerful landmass. Unlike other oceans, its mid-ocean ridges form three branches, diverging in different directions from the central part of the ocean.

The area of ​​the Indian Ocean with seas, bays and straits is 76.17 million km 2, the volume of water is 282.65 million km 3, average depth 3711 m (2nd place after the Pacific Ocean); without them - 64.49 million km 2, 255.81 million km 3, 3967 m. The greatest depth in the deep-water Sunda Trench is 7729 m at 11 ° 10 'south latitude and 114 ° 57 ' east longitude. The shelf zone of the ocean (conditionally depths up to 200 m) occupies 6.1% of its area, the continental slope (from 200 to 3000 m) 17.1%, the bed (over 3000 m) 76.8%. See map.

Seas. There are almost three times fewer seas, bays and straits in the Indian Ocean than in the Atlantic or Pacific Ocean, they are mainly concentrated in its northern part. Seas of the tropical zone: Mediterranean - Red; marginal - Arabian, Laccadive, Andaman, Timor, Arafura; Antarctic zone: marginal - Davis, D'Urville, Cosmonauts, Riiser-Larsen, Commonwealth (see separate articles about the seas). The largest bays: Bengal, Persian, Aden, Oman, Great Australian, Carpentaria, Prydz. Straits: Mozambique, Babel Mandeb, Bass, Hormuz, Malacca, Polk, Tenth Degree, Great Channel.

Islands. Unlike other oceans, the islands are few in number. The total area is about 2 million km2. Most major islands mainland origin - Socotra, Sri Lanka, Madagascar, Tasmania, Sumatra, Java, Timor. Volcanic islands: Reunion, Mauritius, Prince Edward, Crozet, Kerguelen and others; coral - Laccadive, Maldivian, Amirant, Chagos, Nicobar, most of the Andaman, Seychelles; coral Comoros, Mascarene, Cocos and other islands rise on volcanic cones.

coast. The Indian Ocean is characterized by a relatively small indentation of the coastline, with the exception of the northern and northeastern parts, where most of the seas and the main large bays; there are few convenient bays. The coasts of Africa in the western part of the ocean are alluvial, poorly dissected, often surrounded by coral reefs; in the northwestern part - indigenous. In the north, low, slightly dissected coasts with lagoons and sand bars, places with mangroves, bordered by coastal lowlands (Malabar coast, Coromandel coast) prevail, abrasion-accumulative (Konkan coast) and deltaic coasts are also common. In the east, the shores are indigenous, in Antarctica they are covered with glaciers descending to the sea, ending in ice cliffs several tens of meters high.

Bottom relief. In the topography of the bottom of the Indian Ocean, four main elements of geotecture are distinguished: the underwater margins of the continents (including the shelf and the continental slope), transitional zones, or zones of island arcs, the ocean floor, and mid-ocean ridges. The area of ​​the underwater margins of the continents in the Indian Ocean is 17660 thousand km2. The underwater margin of Africa is characterized by a narrow shelf (from 2 to 40 km), its edge is located at a depth of 200-300 m. Only near the southern tip of the mainland, the shelf expands significantly and in the region of the Agulhas plateau extends up to 250 km from the coast. Significant areas of the shelf are occupied by coral structures. The transition from the shelf to the continental slope is expressed by a clear inflection of the bottom surface and a rapid increase in its slope up to 10-15°. The underwater margin of Asia off the coast of the Arabian Peninsula also has a narrow shelf, gradually expanding on the Malabar coast of Hindustan and off the coast of the Bay of Bengal, while the depth at its outer border increases from 100 to 500 m. 4200 m, Sri Lanka). The shelf and the continental slope in some areas are cut by several narrow and deep canyons, the most pronounced canyons, which are underwater continuations of the channels of the Ganges rivers (together with the Brahmaputra River, it annually carries out into the ocean about 1200 million tons of suspended and entrained sediments, which formed a layer of sediments over 3500 m thick ) and Ind. The underwater margin of Australia is distinguished by an extensive shelf, especially in the northern and northwestern parts; in the Gulf of Carpentaria and the Arafura Sea up to 900 km wide; the greatest depth is 500 m. The continental slope to the west of Australia is complicated by underwater ledges and separate underwater plateaus (the greatest height is 3600 m, the Aru Islands). On the underwater margin of Antarctica, everywhere there are traces of the influence of the ice load of a huge glacier covering the mainland. The shelf here belongs to a special glacial type. Its outer boundary almost coincides with the 500 m isobath. The width of the shelf is from 35 to 250 km. The continental slope is complicated by longitudinal and transverse ridges, separate ridges, valleys and deep trenches. At the foot of the continental slope, almost everywhere there is an accumulative plume composed of terrigenous material brought by glaciers. The largest slopes of the bottom are noted in the upper part; with increasing depth, the slope gradually flattens out.

The transition zone at the bottom of the Indian Ocean is distinguished only in the area adjacent to the arc of the Sunda Islands, and represents the south- eastern part Indonesian transitional region. It includes: the basin of the Andaman Sea, the island arc of the Sunda Islands and deep-sea trenches. The most morphologically expressed in this zone is the deep-water Sunda Trench with slopes of 30° or more. Relatively small deep-sea trenches stand out southeast of the island of Timor and east of the Kai Islands, but due to their thick sedimentary layer maximum depths relatively small - 3310 m (Timor Trench) and 3680 m (Kai Trench). The transition zone is extremely seismically active.

The mid-ocean ridges of the Indian Ocean form three submarine mountain ranges, diverging from the area with coordinates 22 ° south latitude and 68 ° east longitude to the northwest, southwest and southeast. Each of the three branches is divided according to morphological features into two independent ridges: the northwestern one - into the Middle Aden Ridge and the Arabian-Indian Ridge, the southwestern one - into the West Indian Ridge and the African-Antarctic Ridge, the southeastern one - into the Central the Indian Ridge and the Australo-Antarctic Rise. Thus, the median ridges divide the bed of the Indian Ocean into three large sectors. The median ridges are vast uplifts fragmented by transform faults into separate blocks with a total length of over 16 thousand km, the foot of which is located at depths of about 5000-3500 m. Relative height ridges 4700-2000 m, width 500-800 km, depth of rift valleys up to 2300 m.

In each of the three sectors of the ocean floor of the Indian Ocean, characteristic relief forms are distinguished: basins, individual ridges, plateaus, mountains, trenches, canyons, etc. In the western sector, the largest basins are: Somali (with depths of 3000-5800 m), -5300 m), Mozambique (4000-6000 m), Madagascar Basin (4500-6400 m), Agulhas (4000-5000 m); underwater ridges: Mascarene Ridge, Madagascar, Mozambique; Plateau: Agulhas, Mozambique Plateau; separate mountains: Equator, Africana, Vernadsky, Hall, Bardin, Kurchatov; Amirant Trench, Mauritius Trench; canyons: Zambezi, Tanganyika and Tagela. In the northeastern sector, basins are distinguished: Arabian (4000-5000 m), Central (5000-6000 m), Cocos (5000-6000 m), North Australian (5000-5500 m), West Australian basin (5000-6500 m), Naturalista (5000-6000 m) and the South Australian Basin (5000-5500 m); underwater ranges: Maldives Ridge, East Indian Ridge, West Australian; Cuvier mountain range; Exmouth Plateau; upland Mill; separate mountains: Moscow State University, Shcherbakov and Afanasy Nikitin; East Indian Trench; canyons: rivers Indus, Ganges, Seatown and Murray. In the Antarctic sector - basins: Crozet (4500-5000 m), African-Antarctic basin (4000-5000 m) and Australo-Antarctic basin (4000-5000 m); plateau: Kerguelen, Crozet and Amsterdam; separate mountains: Lena and Ob. The shapes and sizes of the basins are different: from round ones with a diameter of about 400 km (Komorskaya) to oblong giants 5500 km long (Central), the degree of their isolation and the bottom topography are different: from flat or gently undulating to hilly and even mountainous.

Geological structure. The peculiarity of the Indian Ocean is that its formation occurred both as a result of the split and subsidence of continental masses, and as a result of the expansion of the bottom and the neoformation of the oceanic crust within the mid-ocean (spreading) ridges, the system of which was repeatedly rebuilt. The modern system of mid-ocean ridges consists of three branches, converging at the point of the triple junction of Rodriguez. In the northern branch, the Arabian-Indian Ridge continues to the northwest of the Owen transform fault zone with the rift systems of the Gulf of Aden and the Red Sea and connects with the inland rift systems. East Africa. In the southeastern branch, the Central Indian Ridge and the Australo-Antarctic Rise are separated by the Amsterdam Fault Zone, with which the plateau of the same name is connected with the volcanic islands of Amsterdam and St. Paul. The Arabian-Indian and Central Indian ridges are slow-spreading (the spreading rate is 2-2.5 cm/year), have a well-defined rift valley, and are crossed by numerous transform faults. The wide Australo-Antarctic Rise does not have a pronounced rift valley; spreading rate on it is higher than in other ridges (3.7-7.6 cm/year). South of Australia, the uplift is broken by the Australo-Antarctic fault zone, where the number of transform faults increases and the spreading axis shifts along the faults to the south. The ridges of the southwestern branch are narrow, with a deep rift valley, and are densely crossed by transform faults oriented at an angle to the strike of the ridge. They are characterized by a very low spreading rate (about 1.5 cm/year). The West Indian Ridge is separated from the African-Antarctic Ridge by the Prince Edward, Du Toit, Andrew Bain and Marion faults, which shift the axis of the ridge almost 1000 km to the south. The age of the oceanic crust within the spreading ridges is predominantly Oligocene-Quaternary. The West Indian Ridge, which intrudes into the structures of the Central Indian Ridge as a narrow wedge, is considered the youngest.

The spreading ridges divide the ocean floor into three sectors - the African in the west, the Asian-Australian in the northeast, and the Antarctic in the south. Within the sectors there are various types of intra-oceanic uplift, represented by "aseismic" ridges, plateaus and islands. Tectonic (blocky) uplifts have a block structure with different thicknesses of the crust; often include continental remnants. Volcanic uplifts are mainly associated with fault zones. Uplifts are the natural boundaries of deep-sea basins. The African sector is distinguished by the predominance of fragments of continental structures (including microcontinents), within which the thickness of the earth's crust reaches 17-40 km (the Agulhas and Mozambique plateaus, the Madagascar ridge with the island of Madagascar, individual blocks of the Mascarene plateau with the bank of the Seychelles and the bank of Saya de -Malya). Volcanic uplifts and structures include the Comoros underwater ridge, crowned with archipelagos of coral and volcanic islands, Amirante Range, Reunion Islands, Mauritius, Tromelin, Farquhar massif. In the western part of the African sector of the Indian Ocean (the western part of the Somali Basin, the northern part of the Mozambique Basin), adjacent to the eastern submarine margin of Africa, the age of the earth's crust is predominantly Late Jurassic-Early Cretaceous; in the central part of the sector (Mascarene and Madagascar basins) - Late Cretaceous; in the northeastern part of the sector (eastern part of the Somali Basin) - Paleocene-Eocene. Ancient spreading axes and transform faults crossing them have been identified in the Somali and Mascarene basins.

The northwestern (Asian) part of the Asian-Australian sector is characterized by meridional "aseismic" ridges of a block structure with an increased thickness of the oceanic crust, the formation of which is associated with a system of ancient transform faults. These include the Maldives Ridge, crowned with archipelagos of coral islands - Laccadive, Maldives and Chagos; the so-called 79° ridge, the Lanka ridge with Mount Athanasius Nikitin, the East Indian (the so-called 90° ridge), Investigator, etc. Thick (8-10 km) sediments of the Indus, Ganges and Brahmaputra rivers in the northern Indian Ocean partially overlap in this direction, the ridges, as well as the structures of the transition zone of the Indian Ocean - the southeastern outskirts of Asia. The Murri Range in the northern part of the Arabian Basin, which limits the Oman Basin from the south, is a continuation of the folded land structures; enters the Owen Fault Zone. To the south of the equator, a sublatitudinal zone of intraplate deformations up to 1000 km wide was revealed, which is characterized by high seismicity. It stretches in the Central and Coconut basins from the Maldives Range to the Sunda Trench. The Arabian Basin is underlain by the crust of the Paleocene-Eocene age, the Central Basin - by the crust of the Late Cretaceous - Eocene age; the bark is the youngest in the southern part of the basins. In the Coconut Basin, the age of the crust varies from Late Cretaceous in the south to Eocene in the north; an ancient spreading axis was established in its northwestern part, separating the Indian and Australian lithospheric plates until the middle Eocene. The Cocos Rise, a latitudinal uplift with numerous seamounts and islands (including the Cocos Islands) rising above it, and the Ru Rise, adjacent to the Sunda Trench, separate the southeastern (Australian) part of the Asian-Australian sector. The West Australian basin (Wharton) in the central part of the Asian-Australian sector of the Indian Ocean is underlain in the northwest by the Late Cretaceous crust, in the east by the Late Jurassic. Submerged continental blocks (marginal plateaus of Exmouth, Cuvier, Zenith, Naturalist) divide the eastern part of the basin into separate depressions - Cuvier (north of the Cuvier plateau), Perth (north of the Naturalist plateau). The crust of the North Australian Basin (Argo) is the most ancient in the south (Late Jurassic); becomes younger in a northerly direction (to the early Cretaceous). The age of the crust of the South Australian Basin is Late Cretaceous - Eocene. The Broken Plateau is an intra-oceanic uplift with an increased (from 12 to 20 km, according to various sources) crustal thickness.

In the Antarctic sector of the Indian Ocean, there are mainly volcanic intra-oceanic uplifts with an increased thickness of the earth's crust: the Kerguelen Plateau, Crozet (Del Cano) and Conrad. Within the limits of the largest plateau Kerguelen, supposedly laid down on an ancient transform fault, the thickness of the earth's crust (according to some data, the Early Cretaceous age) reaches 23 km. Towering above the plateau, the Kerguelen Islands are a multiphase volcanoplutonic structure (composed of alkaline basalts and syenites of the Neogene age). On Heard Island - Neogene-Quaternary alkaline volcanic rocks. In the western part of the sector are the Konrad Plateau with volcanic mountains The Ob and Lena, as well as the Crozet plateau with a group of volcanic islands Marion, Prince Edward, Crozet, composed of Quaternary basalts and intrusive massifs of syenites and monzonites. The age of the earth's crust within the African-Antarctic, Australo-Antarctic basins and the Crozet basin is Late Cretaceous - Eocene.

The Indian Ocean is characterized by the predominance of passive margins (the continental margins of Africa, the Arabian and Hindustan peninsulas, Australia, and Antarctica). The active margin is observed in the northeastern part of the ocean (the Sunda zone of the Indian Ocean-Southeast Asia transition), where subduction (underthrust) of the ocean lithosphere occurs under the Sunda island arc. The subduction zone limited in length - Makranskaya - was identified in the northwestern part of the Indian Ocean. Along the Agulhas Plateau, the Indian Ocean borders the African continent along a transform fault.

The formation of the Indian Ocean began in the middle of the Mesozoic during the breakup of the Gondwana part (see Gondwana) of the Patea supercontinent, which was preceded by continental rifting during the Late Triassic - Early Cretaceous. The formation of the first sections of the oceanic crust as a result of the separation of continental plates began in the Late Jurassic in the Somali (about 155 million years ago) and North Australian (151 million years ago) basins. In the Late Cretaceous, the bottom expansion and the neoformation of the oceanic crust experienced the northern part of the Mozambique Basin (140-127 million years ago). The separation of Australia from Hindustan and Antarctica, accompanied by the opening of basins with oceanic crust, began in the Early Cretaceous (about 134 million years ago and about 125 million years ago, respectively). Thus, in the early Cretaceous (about 120 million years ago), narrow oceanic basins arose, cutting into the supercontinent and dividing it into separate blocks. In the middle of the Cretaceous period (about 100 million years ago), the ocean floor began to grow intensively between Hindustan and Antarctica, which led to the drift of Hindustan in a northerly direction. In the time interval of 120-85 million years ago, the spreading axes that existed to the north and west of Australia, off the coast of Antarctica and in the Mozambique Channel, died off. In the Late Cretaceous (90-85 million years ago), a split began between Hindustan with the Mascarene-Seychelles block and Madagascar, which was accompanied by bottom spreading in the Mascarene, Madagascar and Crozet basins, as well as the formation of the Australo-Antarctic Rise. At the turn of the Cretaceous and Paleogene, Hindustan separated from the Mascarene-Seychelles block; the Arabian-Indian spreading ridge arose; spreading axes died off in the Mascarene and Madagascar basins. In the middle of the Eocene, the Indian lithospheric plate merged with the Australian one; the still developing system of mid-ocean ridges was formed. close to modern look The Indian Ocean acquired at the beginning - the middle of the Miocene. In the middle of the Miocene (about 15 million years ago), during the breakup of the Arabian and African plates, a new formation of oceanic crust began in the Gulf of Aden and the Red Sea.

Recent tectonic movements in the Indian Ocean have been noted in mid-ocean ridges (associated with shallow-focus earthquakes), as well as in individual transform faults. The region of intense seismicity is the Sunda island arc, where deep-focus earthquakes are due to the presence of a seismofocal zone plunging in a northeasterly direction. During earthquakes on the northeastern margin of the Indian Ocean, the formation of a tsunami is possible.

Bottom sediments. The rate of sedimentation in the Indian Ocean is generally lower than in the Atlantic and Pacific oceans. The thickness of modern bottom sediments varies from discontinuous distribution on mid-ocean ridges to several hundred meters in deep-water basins and 5000-8000 m at the foot of continental slopes. The most widespread are calcareous (mainly foraminiferal-coccolithic) muds covering over 50% of the ocean floor area (on continental slopes, ridges and the bottom of basins at depths up to 4700 m) in warm oceanic regions from 20° north latitude to 40° south latitude from high biological productivity of waters. Polygenic sediments - red deep-sea oceanic clays - occupy 25% of the bottom area at depths of more than 4700 m in the eastern and southeastern parts of the ocean from 10 ° north latitude to 40 ° south latitude and in bottom areas remote from islands and continents; in the tropics, red clays alternate with siliceous radiolarian silts that cover the bottom of deep-water basins of the equatorial belt. In deep-sea sediments, ferromanganese nodules are present as inclusions. Siliceous, mainly diatomaceous, oozes occupy about 20% of the bottom of the Indian Ocean; distributed at great depths south of 50 ° south latitude. The accumulation of terrigenous sediments (pebbles, gravel, sands, silts, clays) occurs mainly along the coasts of the continents and within their underwater margins in the areas of river and iceberg runoff, significant wind removal of material. Sediments covering the African shelf are mainly of shell and coral origin; phosphorite concretions are widely developed in the southern part. Along the northwestern periphery of the Indian Ocean, as well as in the Andaman Basin and in the Sunda Trench, bottom sediments are mainly represented by deposits of turbidity (turbid) flows - turbidites with the participation of products of volcanic activity, underwater landslides, landslides, etc. Sediments of coral reefs are widespread in the western parts of the Indian Ocean from 20 ° south latitude to 15 ° north latitude, and in the Red Sea - up to 30 ° north latitude. IN rift valley Outcrops of metal-bearing brines with temperatures up to 70°C and salinity up to 300‰ have been found in the Red Sea. In the metal-bearing sediments formed from these brines, the content of non-ferrous and rare metals is high. On continental slopes, seamounts, mid-ocean ridges, outcrops of bedrocks (basalts, serpentinites, peridotites) are noted. Bottom sediments around Antarctica are distinguished in special type iceberg deposits. They are characterized by the predominance of various clastic material, ranging from large boulders to silts and fine silts.

Climate. Unlike the Atlantic and Pacific Oceans, which have a meridional strike from the coast of Antarctica to the Arctic Circle and communicate with the Arctic Ocean, the Indian Ocean in the northern tropical region is bordered by a land mass, which largely determines the characteristics of its climate. The uneven heating of the land and ocean leads to a seasonal change in the vast minima and maxima of atmospheric pressure and to seasonal displacements of the tropical atmospheric front, which retreats southward to almost 10 ° south latitude in the winter of the Northern Hemisphere, and is located in summer at foothill areas south of Asia. As a result, over northern part The Indian Ocean is dominated by a monsoon climate, which is primarily characterized by a change in wind direction during the year. The winter monsoon with relatively weak (3-4 m/s) and stable northeasterly winds operates from November to March. During this period, north of 10 ° south latitude, calms are not uncommon. The summer monsoon with southwesterly winds is observed from May to September. In the northern tropical region and in the equatorial zone of the ocean, the average wind speed reaches 8-9 m/s, often reaching storm strength. In April and October, the baric field is usually restructured, and in these months the wind situation is unstable. Against the background of the prevailing monsoonal atmospheric circulation over the northern part of the Indian Ocean, individual manifestations of cyclonic activity are possible. During the winter monsoon, there are cases of cyclones developing over the Arabian Sea, during the summer monsoon - over the waters of the Arabian Sea and the Bay of Bengal. Strong cyclones in these areas are sometimes formed during the periods of monsoon change.

At about 30° south latitude in the central part of the Indian Ocean, there is a stable area of ​​high pressure, the so-called South Indian High. This stationary anticyclone - component southern subtropical high pressure area - persists all year round. The pressure at its center varies from 1024 hPa in July to 1020 hPa in January. Under the influence of this anticyclone, in the latitudinal band between 10 and 30 ° south latitude, stable southeast trade winds blow throughout the year.

South of 40° South latitude, atmospheric pressure in all seasons decreases uniformly from 1018-1016 hPa at the southern periphery of the South Indian High to 988 hPa at 60° South latitude. Under the influence of the meridional pressure gradient in the lower layer of the atmosphere, a stable westerly transport of air is maintained. The highest average wind speed (up to 15 m/s) is observed in the middle of winter in the Southern Hemisphere. For the higher southern latitudes of the Indian Ocean, storm conditions are typical throughout almost the entire year, under which winds with speeds of more than 15 m/s, causing waves with a height of more than 5 m, have a frequency of 30%. East winds and two or three cyclones per year are usually observed south of 60 ° south latitude along the coast of Antarctica, most often in July - August.

In July, the highest air temperatures in the near layer of the atmosphere are observed at the top of the Persian Gulf (up to 34°C), the lowest - off the coast of Antarctica (-20°C), over the Arabian Sea and the Bay of Bengal, on average 26-28°C. Over the water area of ​​the Indian Ocean, the air temperature changes almost everywhere in accordance with the geographical latitude.

In the southern part of the Indian Ocean, it gradually decreases from north to south by about 1°C for every 150 km. In January, the highest air temperatures (26-28°C) are observed in the equatorial zone, near the northern coasts of the Arabian Sea and the Bay of Bengal - about 20°C. In the southern part of the ocean, the temperature drops evenly from 26°C in the Southern Tropic to 0°C and somewhat lower at the latitude of the Antarctic Circle. The amplitude of annual fluctuations in air temperature over most of the Indian Ocean is on average less than 10°C, and only off the coast of Antarctica increases to 16°C.

The greatest amount of precipitation per year falls in the Bay of Bengal (over 5500 mm) and off the eastern coast of the island of Madagascar (over 3500 mm). In the northern coastal part of the Arabian Sea, the least amount of precipitation falls (100-200 mm per year).

The northeastern regions of the Indian Ocean are located in seismically active areas. The eastern coast of Africa and the island of Madagascar, the coasts of the Arabian Peninsula and the Hindustan Peninsula, almost all island archipelagos of volcanic origin, the western coasts of Australia, especially the arc of the Sunda Islands, in the past were repeatedly exposed to tsunami waves of various strengths, up to catastrophic ones. In 1883, after the explosion of the Krakatoa volcano in the Jakarta region, a tsunami with a wave height of over 30 m was recorded, in 2004 a tsunami caused by an earthquake in the region of Sumatra had catastrophic consequences.

hydrological regime. Seasonality in changes in hydrological characteristics (primarily temperature and currents) is most clearly manifested in the northern part of the ocean. The summer hydrological season here corresponds to the time of the southwest monsoon (May - September), the winter - the northeast monsoon (November - March). A feature of the seasonal variability of the hydrological regime is that the restructuring of the hydrological fields is somewhat late relative to the meteorological fields.

Water temperature. In the winter of the Northern Hemisphere, the highest water temperatures in the surface layer are observed in the equatorial zone - from 27°C off the coast of Africa to 29°C or more east of the Maldives. In the northern regions of the Arabian Sea and the Bay of Bengal, the water temperature is about 25°C. In the southern part of the Indian Ocean, a zonal distribution of temperature is characteristic everywhere, which gradually decreases from 27-28 ° С at 20 ° south latitude to negative values ​​\u200b\u200bat the edge of drifting ice, located approximately at 65-67 ° south latitude. In the summer season, the highest water temperatures in the surface layer are observed in the Persian Gulf (up to 34°С), in the northwest of the Arabian Sea (up to 30°С), in the eastern part of the equatorial zone (up to 29°С). IN coastal areas On the Somali and Arabian peninsulas, abnormally low values ​​​​are observed at this time of the year (sometimes less than 20 ° C), which is the result of the rise to the surface of cooled deep waters in the Somali Current system. In the southern part of the Indian Ocean, the distribution of water temperature throughout the year retains a zonal character, with the difference that its negative values ​​\u200b\u200bin the winter of the Southern Hemisphere are found much further north, already at about 58-60 ° south latitude. The amplitude of annual fluctuations in water temperature in the surface layer is small and averages 2-5°C, only in the region of the Somali coast and in the Gulf of Oman of the Arabian Sea exceeds 7°C. The water temperature rapidly decreases vertically: at a depth of 250 m, it drops below 15°C almost everywhere, and below 1000 m - below 5°C. At a depth of 2000 m, temperatures above 3°C are observed only in the northern part of the Arabian Sea, in the central regions - about 2.5°C, in the southern part it decreases from 2°C at 50° south latitude to 0°C off the coast of Antarctica. Temperatures in the deepest (over 5000 m) basins range from 1.25°С to 0°С.

The salinity of the surface waters of the Indian Ocean is determined by the balance between the amount of evaporation and the total amount of precipitation and river runoff for each area. The absolute maximum of salinity (over 40‰) is observed in the Red Sea and the Persian Gulf, in the Arabian Sea everywhere, except for a small area in the southeastern part, salinity is above 35.5‰, in the band of 20-40 ° south latitude - more than 35‰ . The area of ​​low salinity is located in the Bay of Bengal and in the area adjacent to the arc of the Sunda Islands, where there is a large fresh river runoff and precipitation the largest number precipitation. In the northern part of the Bay of Bengal in February, salinity is 30-31‰, in August - 20‰. An extensive tongue of waters with a salinity of up to 34.5 ‰ at 10 ° south latitude extends from the island of Java to 75 ° east longitude. In Antarctic waters, salinity is everywhere below the average oceanic value: from 33.5‰ in February to 34.0‰ in August, its changes are determined by slight salinity during the formation sea ​​ice and corresponding desalination during the period of ice melting. seasonal changes salinity is noticeable only in the upper, 250-meter layer. With increasing depth, not only seasonal fluctuations, but also the spatial variability of salinity fade, deeper than 1000 m it fluctuates between 35-34.5‰.

Density. The highest water density in the Indian Ocean is noted in the Suez and Persian Gulfs (up to 1030 kg / m 3) and in cold Antarctic waters (1027 kg / m 3), the average - in the warmest and most saline waters in the northwest (1024-1024, 5 kg / m 3), the smallest - in the most fresh waters in the northeastern part of the ocean and in the Bay of Bengal (1018-1022 kg / m 3). With depth, mainly due to a decrease in water temperature, its density increases, sharply increasing in the so-called jump layer, which is most pronounced in the equatorial zone of the ocean.

Ice regime. The severity of the climate in the southern part of the Indian Ocean is such that the process of formation of sea ice (at air temperatures below -7 ° C) can occur almost all year round. The maximum development of the ice cover reaches in September - October, when the width of the drifting ice belt reaches 550 km, the smallest - in January - February. The ice cover is characterized by high seasonal variability and its formation is very fast. The ice edge moves to the north at a speed of 5-7 km/day, just as quickly (up to 9 km/day) retreats to the south during the melting period. Fast ice is established annually, reaches an average width of 25-40 km and almost completely melts by February. Drifting ice near the coasts of the mainland moves under the influence of katabatic winds in the general direction to the west and northwest. Near the northern edge, the ice drifts eastward. A characteristic feature of the Antarctic ice cover is a large number of icebergs breaking off from the outlet and ice shelves of Antarctica. Table-shaped icebergs are especially large, which can reach a gigantic length of several tens of meters, towering 40-50 meters above the water. Their number rapidly decreases with distance from the coast of the mainland. The duration of the existence of large icebergs is on average 6 years.

currents. The circulation of surface waters in the northern part of the Indian Ocean is formed under the influence of monsoon winds and therefore varies significantly from summer season to winter. In February, from 8° north latitude Nicobar Islands to 2 ° north latitude off the coast of Africa there is a surface winter monsoon current with speeds of 50-80 cm / s; with a rod passing approximately along 18 ° south latitude, the South Equatorial Current propagates in the same direction, having an average speed on the surface of about 30 cm / s. Connecting off the coast of Africa, the waters of these two streams give rise to the Inter-trade countercurrent, which carries its waters to the east with velocities in the core of about 25 cm/s. Along the North African coast with a general direction to the south, the waters of the Somali current move, partially passing into the Intertrade countercurrent, and to the south - the Mozambique and Cape Agulhas currents going south at speeds of about 50 cm/s. Part of the South Equatorial Current off the east coast of the island of Madagascar turns south along it (the Madagascar Current). South of 40 ° south latitude, the entire water area of ​​the ocean is crossed from west to east by the flow of the longest and most powerful West Wind Current in the World Ocean (Antarctic Circumpolar Current). The velocities in its rods reach 50 cm/s, and the flow rate is about 150 million m 3 /s. At 100-110 ° east longitude, a stream branches off from it, heading north and giving rise to the West Australian Current. In August, the Somali current follows in a general direction to the northeast and, at a speed of up to 150 cm / s, draws water into the northern part of the Arabian Sea, from where the Monsoon current, skirting the western and southern coasts of the Hindustan peninsula and the island of Sri Lanka, carries water to the shores of the island Sumatra, turns south and merges with the waters of the South Trade Wind. Thus, an extensive clockwise circulation is created in the northern part of the Indian Ocean, consisting of the Monsoon, South Equatorial and Somali currents. In the southern part of the ocean, from February to August, the pattern of currents changes little. Off the coast of Antarctica in a narrow coastal strip, a current is observed all year round, caused by katabatic winds and directed from east to west.

water masses. In the vertical structure of the water masses of the Indian Ocean, according to hydrological characteristics and depth of occurrence, surface, intermediate, deep and bottom waters are distinguished. Surface waters are distributed in a relatively thin surface layer and occupy the upper 200-300 m on average. From north to south, water masses stand out in this layer: Persian and Arabian in the Arabian Sea, Bengal and South Bengal in the Bay of Bengal; further south of the equator - Equatorial, Tropical, Subtropical, Subantarctic and Antarctic. As the depth increases, the differences between neighboring water masses decrease and their number decreases accordingly. So, in intermediate waters, the lower limit of which reaches 2000 m in temperate and low latitudes and up to 1000 m in high latitudes, Persian and Red Sea in the Arabian Sea, Bengal in the Bay of Bengal, Subantarctic and Antarctic intermediate water masses are distinguished. Deep waters are represented by the North Indian, Atlantic (in the western part of the ocean), Central Indian (in the eastern part), and Circumpolar Antarctic water masses. Bottom water everywhere, except for the Bay of Bengal, is represented by one Antarctic bottom water mass, which fills all deep-water basins. The upper limit of bottom water is located on average at a horizon of 2500 m off the coast of Antarctica, where it forms, up to 4000 m in the central regions of the ocean and rises to almost 3000 m north of the equator.

Tides and excitement. Semidiurnal and irregular semidiurnal tides are most widespread on the shores of the Indian Ocean. Semi-diurnal tides are observed on the African coast south of the equator, in the Red Sea, off the northwestern shores of the Persian Gulf, in the Bay of Bengal, off the northwestern coast of Australia. Irregular semidiurnal tides - off the Somali Peninsula, in the Gulf of Aden, off the coast of the Arabian Sea, in the Persian Gulf, off the southwestern coast of the Sunda island arc. Diurnal and irregular diurnal tides are observed near the western and southern shores Australia. The highest tides are off the northwestern coast of Australia (up to 11.4 m), in the mouth zone of the Indus (8.4 m), in the mouth zone of the Ganges (5.9 m), off the coast of the Mozambique Channel (5.2 m) ; in the open ocean, tides vary from 0.4 m near the Maldives to 2.0 m in the southeastern Indian Ocean. The excitement reaches its greatest strength in temperate latitudes in the zone of action of westerly winds, where the frequency of waves with a height of over 6 m is 17% per year. Near Kerguelen Island, waves 15 m high and 250 m long were recorded, off the coast of Australia, 11 m and 400 m, respectively.

Flora and fauna. The main part of the Indian Ocean is located within the tropical and southern temperate zones. The absence of the northern high-latitude region in the Indian Ocean and the action of monsoons lead to two differently directed processes that determine the characteristics of the local flora and fauna. The first factor hinders deep-sea convection, which negatively affects the renewal of deep waters in the northern part of the ocean and the increase in oxygen deficiency in them, which is especially pronounced in the Red Sea intermediate water mass, which leads to depletion of the species composition and reduces the total zooplankton biomass in the intermediate layers. When oxygen-poor waters in the Arabian Sea reach the shelf, local kills occur (death of hundreds of thousands of tons of fish). At the same time, the second factor (monsoons) creates favorable conditions for high biological productivity in coastal areas. Under the influence of the summer monsoon, water is driven off along the Somali and Arabian coasts, which causes a powerful upwelling that brings to the surface waters rich in nutrient salts. The winter monsoon, although to a lesser extent, leads to seasonal upwelling with similar effects in west coast peninsulas of Hindustan.

The coastal zone of the ocean is characterized by the greatest species diversity. The shallow waters of the tropical zone are characterized by numerous 6- and 8-ray stony corals, hydrocorals, which, together with red algae, can create underwater reefs and atolls. The richest fauna of various invertebrates (sponges, worms, crabs, mollusks, sea urchins, brittle stars and starfish), small but brightly colored fish of coral reefs live among the powerful coral structures. Most of The coasts are occupied by mangroves. At the same time, the fauna and flora of the beaches and rocks that dry out at low tide are quantitatively depleted due to the depressing effect of the sun's rays. IN temperate zone life on such sections of the coast is much richer; dense thickets of red and brown algae (kelp, fucus, macrocystis) develop here, various invertebrates are abundant. According to L. A. Zenkevich (1965), over 99% of all species of bottom and bottom animals living in the ocean live in the littoral and sublittoral zones.

For open spaces The Indian Ocean, especially for the surface layer, is also characterized by rich flora. The food chain in the ocean begins with microscopic unicellular plant organisms - phytoplankton, which inhabits mainly the uppermost (about 100-meter) layer of ocean waters. Among them, several species of peridinium and diatom algae predominate, and in the Arabian Sea - cyanobacteria (blue-green algae), often causing the so-called water bloom during mass development. There are three areas of the highest phytoplankton production in the northern Indian Ocean: the Arabian Sea, the Bay of Bengal and the Andaman Sea. The greatest production is observed off the coast of the Arabian Peninsula, where the number of phytoplankton sometimes exceeds 1 million cells/l (cells per liter). Its high concentrations are also observed in the subantarctic and antarctic zones, where during spring flowering there are up to 300,000 cells / l. The lowest phytoplankton production (less than 100 cells/l) is observed in the central part of the ocean between parallels 18 and 38° south latitude.

Zooplankton inhabits almost the entire thickness of oceanic waters, but its number rapidly decreases with increasing depth and decreases by 2-3 orders of magnitude towards the bottom layers. The food for most of the zooplankton, especially those living in the upper layers, is phytoplankton, so the patterns of spatial distribution of phyto- and zooplankton are largely similar. The highest rates of zooplankton biomass (from 100 to 200 mg/m3) are observed in the Arabian and Andaman Seas, the Bengal, Aden and Persian Gulfs. The main biomass of ocean animals is copepods (more than 100 species), somewhat less pteropods, jellyfish, siphonophores and other invertebrates. Of the unicellular, radiolarians are typical. In the Antarctic region of the Indian Ocean, a huge number of euphausian crustaceans of several species, united under the name "krill", is characteristic. Euphausiids form the main food base for the largest animals on Earth - baleen whales. In addition, fish, seals, cephalopods, penguins and other bird species feed on krill.

Organisms that move freely in the marine environment (nekton) are represented in the Indian Ocean mainly by fish, cephalopods, and cetaceans. Of the cephalopods in the Indian Ocean, cuttlefish, numerous squids and octopuses are common. Of the fish, the most abundant are several species of flying fish, luminous anchovies (dollfish), sardinella, sardine, mackerel pike, notothenia, sea bass, several types of tuna, blue marlin, grenadier, sharks, rays. They live in warm waters sea ​​turtles and venomous sea snakes. The fauna of aquatic mammals is represented by various cetaceans. Of the baleen whales, the following are common: blue, sei whale, fin whale, humpback whale, Australian (Cape) Chinese. Toothed whales are represented by sperm whales, several species of dolphins (including killer whales). In the coastal waters of the southern part of the ocean, pinnipeds are widespread: Weddell seal, crabeater seal, seals - Australian, Tasmanian, Kerguelen and South African, Australian sea lion, sea leopard, etc. Among the birds, the most characteristic are the wandering albatross, petrels, large frigate, phaetons , cormorants, gannets, skuas, terns, gulls. South of 35° south latitude, on the coasts South Africa, Antarctica and islands - numerous colonies of several species of penguins.

In 1938, a unique biological phenomenon was discovered in the Indian Ocean - the living lobe-finned fish Latimeria chalumnae, which was considered extinct tens of millions of years ago. The "fossil" coelacanth lives at a depth of more than 200 m in two places - near the Comoros and in the waters of the Indonesian archipelago.

Research history

The northern coastal regions, especially the Red Sea and deeply incised bays, began to be used by man for navigation and fishing already in the era of ancient civilizations, several thousand years before our era. For 600 years BC, the Phoenician navigators, who were in the service of the Egyptian pharaoh Necho II, circled Africa by sea. In 325-324 BC, Alexander the Great's colleague Nearchus, commanding a fleet, sailed from India to Mesopotamia and compiled the first descriptions of the coast from the mouth of the Indus River to the top of the Persian Gulf. In the 8th-9th centuries, the Arabian Sea was intensively explored by Arab navigators, who created the first sailing directions and navigational guides for this area. In the first half of the 15th century, Chinese navigators led by Admiral Zheng He made a series of voyages along the Asian coast to the west, reaching the coast of Africa. In 1497-99, the Portuguese Gama (Vasco da Gama) laid a sea route for Europeans to India and the countries of Southeast Asia. A few years later, the Portuguese discovered the island of Madagascar, the Amirante, Comoros, Mascarene and Seychelles. Following the Portuguese, the Dutch, French, Spanish and British entered the Indian Ocean. The name "Indian Ocean" first appeared on European maps in 1555. In 1772-75, J. Cook penetrated the Indian Ocean to 71° south latitude and made the first deep-sea measurements. Oceanographic studies of the Indian Ocean began with systematic measurements of water temperature during the round-the-world voyages of the Russian ships Rurik (1815-18) and Enterprise (1823-26). In 1831-36, an English expedition took place on the Beagle ship, on which Charles Darwin carried out geological and biological work. Comprehensive oceanographic measurements in the Indian Ocean were carried out during the British expedition on board the Challenger in 1873-74. Oceanographic work in the northern part of the Indian Ocean was carried out in 1886 by S. O. Makarov on the ship Vityaz. In the first half of the 20th century, oceanographic observations began to be carried out regularly, and by the 1950s they were carried out at almost 1500 deep-sea oceanographic stations. In 1935, the monograph "Geography of the Indian and Pacific Oceans" by P. G. Schott was published - the first major publication that summarized the results of all previous studies in this region. In 1959, the Russian oceanographer A. M. Muromtsev published a fundamental work - "The main features of the hydrology of the Indian Ocean." In 1960-65, the Scientific Committee on Oceanography of UNESCO conducted the International Indian Ocean Expedition (IIOE), the largest of those previously operating in the Indian Ocean. Scientists from more than 20 countries of the world (USSR, Australia, Great Britain, India, Indonesia, Pakistan, Portugal, USA, France, Germany, Japan, etc.) took part in the MIOE program. During the MIOE, major geographical discoveries were made: the underwater West Indian and East Indian ridges, tectonic fault zones - Owen, Mozambique, Tasman, Diamantina, etc., seamounts - the Ob, Lena, etc., deep-sea trenches - Ob, Chagos, Vima, Vityaz, etc. In the history of the study of the Indian Ocean, the results of research carried out in 1959-77 by the Vityaz research vessel (10 voyages) and dozens of other Soviet expeditions on ships of the Hydrometeorological Service stand out and the State Committee for Fisheries. Since the early 1980s, ocean research has been carried out within the framework of 20 international projects. The research of the Indian Ocean became especially active during the International World Ocean Circulation Experiment (WOCE). Since its successful completion in the late 1990s, the amount of modern oceanographic information for the Indian Ocean has doubled.

Economic use

The coastal zone of the Indian Ocean is characterized by an exceptionally high population density. Over 35 states are located on the coasts and islands of the ocean, in which about 2.5 billion people (over 30% of the world's population) live. The bulk of the coastal population is concentrated in South Asia (more than 10 cities with a population of over 1 million people). In most countries of the region, the problems of gaining living space, creating jobs, providing food, clothing and housing, and medical care are acute.

The use of the Indian Ocean, as well as other seas and oceans, is carried out in several main areas: transport, fishing, mining, and recreation.

Transport. The role of the Indian Ocean in maritime transportation increased significantly with the creation of the Suez Canal (1869), which opened a short sea route of communication with the states washed by the waters of the Atlantic Ocean. The Indian Ocean is an area of ​​transit and export of all kinds of raw materials, in which almost all major seaports are of international importance. In the northeastern part of the ocean (in the Straits of Malacca and Sunda) there are routes for ships going to the Pacific Ocean and back. The main export item to the USA, Japan and the countries of Western Europe is crude oil from the Persian Gulf region. In addition, agricultural products are exported - natural rubber, cotton, coffee, tea, tobacco, fruits, nuts, rice, wool; wood; mineral raw materials - coal, iron ore, nickel, manganese, antimony, bauxite, etc.; machinery, equipment, tools and hardware, chemicals and pharmaceuticals, textiles, cut gems and jewellery. The Indian Ocean accounts for about 10% of the world's shipping traffic; at the end of the 20th century, about 0.5 billion tons of cargo per year was transported through its waters (according to IOC). According to these indicators, it ranks third after the Atlantic and Pacific Oceans, yielding to them in terms of the intensity of shipping and total volumes of cargo transportation, but surpassing all other sea transport communications in terms of oil transportation. The main transport routes across the Indian Ocean are directed to the Suez Canal, the Strait of Malacca, the southern tip of Africa and Australia, and along the northern coast. Shipping is most intensive in the northern regions, although it is limited by storm conditions during the summer monsoon, less intensive in the central and southern regions. The growth in oil production in the Persian Gulf countries, in Australia, Indonesia and other places contributed to the construction and modernization of oil ports and the emergence of giant tankers in the Indian Ocean.

Most developed highways for the transportation of oil, gas and oil products: the Persian Gulf - the Red Sea - the Suez Canal - the Atlantic Ocean; Persian Gulf - Strait of Malacca - Pacific Ocean; the Persian Gulf - the southern tip of Africa - the Atlantic Ocean (especially before the reconstruction of the Suez Canal, 1981); The Persian Gulf - the coast of Australia (the port of Fremantle). Mineral and agricultural raw materials, textiles, precious stones, jewelry, equipment, computer equipment are transported from India, Indonesia, and Thailand. Australia transports coal, gold, aluminium, alumina, iron ore, diamonds, uranium ores and concentrates, manganese, lead, zinc; wool, wheat, meat products, as well as internal combustion engines, cars, electrical products, river boats, glass products, rolled steel, etc. Industrial goods, cars, electronic equipment, etc. predominate in oncoming flows. ocean is occupied by the carriage of passengers.

Fishing. Compared to other oceans, the Indian Ocean has a relatively low biological productivity; fish and other seafood accounts for 5-7% of the total world catch. The catch of fish and non-fish objects is concentrated mainly in the northern part of the ocean, and in the west it is twice as large as the catch in the eastern part. The largest production volumes of bioproducts are observed in the Arabian Sea off the western coast of India and off the coast of Pakistan. Shrimps are harvested in the Persian and Bengal bays, and lobsters are harvested off the east coast of Africa and on tropical islands. In the open areas of the ocean in the tropical zone, tuna fishing is widely developed, which is carried out by countries with a well-developed fishing fleet. In the Antarctic region, nototheniids, ice fish and krill are mined.

Mineral resources. Deposits of oil and natural combustible gas or oil and gas shows have been discovered practically throughout the shelf area of ​​the Indian Ocean. Actively developed oil and gas fields are of the greatest industrial importance in the bays: Persian (Persian Gulf oil and gas basin), Suez (gas basin of the Gulf of Suez), Cambay (Kambay oil and gas basin), Bengal (Bengal oil and gas basin); off the northern coast of the island of Sumatra (North Sumatra oil and gas basin), in the Timor Sea, off the northwestern coast of Australia (gas-bearing Carnarvon basin), in the Bass Strait (gas-bearing Gippsland basin). Gas deposits have been explored in the Andaman Sea, oil and gas bearing areas - in the Red Sea, the Gulf of Aden, along the coast of Africa. Coastal-marine placers of heavy sands are mined off the coast of the island of Mozambique, along the southwestern and northeastern coasts of India, off the northeastern coast of the island of Sri Lanka, along the southwestern coast of Australia (mining of ilmenite, rutile, monazite and zircon); in the coastal regions of Indonesia, Malaysia, Thailand (cassiterite mining). Industrial accumulations of phosphorites have been discovered on the shelves of the Indian Ocean. Large fields of ferromanganese nodules, a promising source of Mn, Ni, Cu, and Co, have been established on the ocean floor. In the Red Sea, metal-bearing brines and sediments have been identified as potential sources for the extraction of iron, manganese, copper, zinc, nickel, etc.; there are deposits of rock salt. In the coastal zone of the Indian Ocean, sand is mined for construction and glass production, gravel, limestone.

Recreational resources. From the 2nd half of the 20th century great importance for the economy of coastal countries has the use of recreational resources of the ocean. Old resorts are being developed and new ones are being built on the coast of the continents and on numerous tropical islands in the ocean. The most visited resorts are in Thailand (the island of Phuket, etc.) - over 13 million people a year (together with the coast and islands of the Gulf of Thailand in the Pacific Ocean), in Egypt [Hurghada, Sharm el-Sheikh (Sharm el-Sheikh), etc. ] - over 7 million people, in Indonesia (the islands of Bali, Bintan, Kalimantan, Sumatra, Java, etc.) - over 5 million people, in India (Goa, etc.), in Jordan (Aqaba), in Israel (Eilat) , in the Maldives, Sri Lanka, Seychelles, Mauritius, Madagascar, South Africa, etc.

Sharm El Sheikh. Hotel "Concord".

Port cities. On the shores of the Indian Ocean there are specialized oil loading ports: Ras-Tannura (Saudi Arabia), Kharq (Iran), Ash-Shuaiba (Kuwait). Major ports Indian Ocean: Port Elizabeth, Durban (South Africa), Mombasa (Kenya), Dar es Salaam (Tanzania), Mogadishu (Somalia), Aden (Yemen), El Kuwait (Kuwait), Karachi (Pakistan), Mumbai, Chennai, Kolkata, Kandla (India), Chittagong (Bangladesh), Colombo (Sri Lanka), Yangon (Myanmar), Fremantle, Adelaide and Melbourne (Australia).

Lit .: Geological and geophysical atlas of the Indian Ocean. M., 1975; Kanaev VF Relief of the bottom of the Indian Ocean. M., 1979; Indian Ocean. L., 1982; Udintsev GB Regional geomorphology of the ocean floor. Indian Ocean. M., 1989; Lithosphere of the Indian Ocean: according to geophysical data / Ed. A. V. Chekunov, Yu. P. Nepronov. K., 1990; Neiman V. G., Burkov V. A., Shcherbinin A. D. Dynamics of the waters of the Indian Ocean. M., 1997; Pushcharovsky Yu. M. Tectonics of the Earth. Fav. works. M., 2005. Vol. 2: Tectonics of the oceans.

M. G. Deev; N. N. Turko (geological structure).

The Indian Ocean is the 3rd largest in the world in terms of its size, located off the coast of Africa, Australia, Eurasia and Antarctica.

Seas, straits and bays occupy 15% and amount to 11.68 million km2. The main ones are: the Arabian Sea (Oman, Aden, Persian Gulf), Red, Andaman, Laccadive, Timor and Arafura Seas; Great Australian and Bay of Bengal.

Large seas of the Indian Ocean - Arabian and Red. In size, they are ahead of their "neighbors" in the Indian Ocean, being the largest among them. The most interesting facts about these seas will be considered below.

Arabian Sea

Between the Arabian Peninsula and Hindustan is the Indian Ocean - Arabian. Its area is huge and is 4832 thousand km², the volume of liquid is 14,514 thousand km³, the most deep point- 5803 m.

The most striking "paradise" place of the Arabian Sea are the Maldives - covered with sand Coral reefs. Lack of sources fresh water is an interesting fact of these islands. Majority local residents use desalinated water or collect rainwater.

Red sea

The total area is 450 thousand km², the volume of water in the sea is 251 thousand km³, the deepest depression is 2211 m. This sea of ​​the Indian Ocean is called the most saline in the world. Yes, yes, it is Red, and not Dead (which has no drains, which means it is a lake).

This sea of ​​the Indian Ocean is not considered deep, its bottom is mostly flat and does not exceed a depth of 200 m, with the exception of existing depressions.

Large oil and gas reserves are of particular interest. True, the right to extract resources between Australia and Timor today is controversial.

Arafura Sea

This is a young sea that arose as a result of an increase in the water level of the oceans. Its area is 1017 thousand km², and the volume of water is 189 thousand km³, the deepest depression is 3680 m, salinity is 32-35 g / l, the average water temperature is 25-28 degrees.

Arafura - the sea of ​​the Indian Ocean, "settled" at its outskirts. In addition, it connects this sea with Due to the proximity and similar climate with the Timor Sea, they are called "twin seas".

Typhoons are a frequent occurrence in the Arafura Sea.

The seas of the Indian Ocean are characterized by a rich and diverse fauna, and are also excellent resort areas.

Located in the northern Indian Ocean. In the east it is bounded by the Indochina peninsula, in the west by the Andaman Islands, in the south by the island of Sumatra. The area of ​​the sea is 605 thousand sq. km, the average depth is 1043 m, the largest reaches 4507 m.

Like many tropical waters, the Andaman Sea boasts a rich underwater world. More than 400 species of fish live here, among which there are such unusual ones as sailboats and flying fish, angel fish and butterfly fish.

Currently, the Andaman Sea is one of the most popular tourist centers. Its coast is a whole constellation worldwide famous resorts- Phuket, Krabi, Phi Phi Islands, Kuala Lumpur.

Located in the northern part of the ocean between two large peninsulas Asia: Arabian and Hindustan. The area of ​​the sea is 3.8 million sq. km, the average depth is 2734 m, the maximum depth is 4652 m.

The sea is named after the peninsula of the same name, but in ancient times it was called in a completely different way: Green, Omani, Eritrean, Persian, Sindhu Sea.

By number of inhabitants underwater world The Arabian Sea is one of the richest on earth. More than 100 commercial fish species live here.

The sea is of great transport importance. Firstly, the main sea routes through the Suez Canal lie here. Secondly, the Arabian Sea transports oil from the Persian Gulf.

Separates Australia from the island of New Guinea. The area is 1 million sq. km, the average depth is 186 m, although the greatest depth is recorded at around 3680 m.

The sea got its name from the name of the local tribe, the natives of the Moluccas - "alfurs". Translated from the local dialect, "alfura" means "inhabitant of the forests."

One of the richest seas of the Indian Ocean, which is home to almost a third of all species of flora and fauna represented in this ocean.

One of the attractive features of the Arafura Sea is clean and transparent water. The lands surrounding the reservoir are sparsely populated. There is no mining activity and no major ports. Therefore, nothing threatens the ecology of the sea yet.

A long ribbon stretched along the coasts of Egypt, Sudan, Saudi Arabia, Israel, Djibouti, Jordan and Yemen. It is an inland sea separating Africa and Asia. The area is 450 thousand sq. km, the average depth is 437 m.

The Red Sea is considered the most salty in the world. 1 liter of water here contains 41 g of salt (for comparison: in the Black - 18 g, in the Baltic - 5 g). There are two reasons for this salinity:

1. Not a single river flows into the Red Sea. But it is the rivers that desalinate the sea water.

2. A lot of metal-bearing brines were found at the bottom of the sea.

The uniqueness of the Red Sea lies in the fact that it is the richest in species diversity among all the reservoirs of the northern hemisphere. There are 13 species of sharks, 14 species of moray eels, and among hundreds of species of fish, 30% are endemic.

The Red Sea is also the most transparent in the world. It is no coincidence that divers love it so much and often call it an "underwater resort".

- a marginal sea located between the southwestern coast of Hindustan, the Laccadive Islands and the Maldives. The area is 786 thousand sq. km, the average depth is 1929 m.

Despite the monsoon climate, the sea remains warm all year round, in summer the water temperature is 28-29ºC, in summer it rarely drops below +25ºC. The southern part of the sea abounds with corals. This sea is the main industrial maritime region for India, where fishing and shrimp and lobster fishing flourish.

Separates Australia and the island of Timor. The area is 432 thousand sq. km, the average depth is 435 m.

The Timor Sea is famous for its hydrocarbon reserves. Oil and gas production has already been established here and new deposits are being searched. The proximity to the equator determined the climate - the waters of the water area are warm throughout the year, storms are a rare occurrence. But shallow water has become the reason that typhoons often dominate here, especially during the rainy season.

Translated from Portuguese, "Timorese" means "orange sea".