Indian Ocean is surrounded by Asia in North and East, Australia in East, Antarctica in south and Africa in west.  It’s average depth is about 4000m. The major part of the coastal lands of Indian Ocean are parts of Gondwana Rock system hence are compact and solid.

• It lacks in numbers of marginal seas, i.e. there are only few number of such seas(like Mozambique channel, Red Sea, Persian Gulf, Bay of Bengal etc.) than Pacific and Atlantic Ocean.
• Some big Islands of Indian Ocean are Madagascar, Srilanka, Maldives, Mauritius, Andaman and Nicobar islands. 

According to Johnson Indian Ocean can be divided into 3 parts:-

1. The western zone – West of Mid-Oceanic Ridge having avg. depth of 3650m, This zone has large number of Islands. 
2. The central Zone –  This zone is less deeper as it contain Mid-Oceanic Ridges.
3. The Eastern zone – This zone is deepest having average depth of 5500 metre. It also contain some Islands like Andaman Nicobar Islands but lesser in number.

The Indian Ocean Bottom can be studied in four pats – 

Continental Shelf

• This is wider along the African coast as wells as along the margins of Arabian Sea and Bay of Bengal .
• However continental shelf is more wider in western part (640 km) while it is lesser wider in Eastern part (160 km) along the coast of Java and Sumatra.
• Even Madagascar is an island in the western margin of the ocean is situated on the Continental shelf of African coastal margins.

Mid Oceanic Ridge

• In India Ocean almost in middle of the ocean from the southern tip of Peninsular India to Antarctica running almost North to south having multiple branches.
• Some of the important branches of the Mid-Oceanic Ridge are :- 

(a) Laccadive-Chagos Ridge 

• Running from Laccadive to Maldives having average width fo 320 km (zero degree North to 30 degree South) 

(b) Chagos-St. Paul Ridge

• Running from Maldives to St. Paul (from 30° south to 50° South running from North-East to South-West having average depth of 320 km.

(c) Amsterdam-St. Paul Plateau

• Running from 30° South to 50° South
• Average width is about 1600 km. From 50° South Central Ridge is bifurcated into two Ridges given below:-

(d) Kerguelen-Gausberg Ridge

• This is the western part of the branch running from 40° South to 63° South.

(e) Indian-Antarctic Ridge

• From St. Paul to 50° South to 63° South. It connects the Mid-Oceanic Ridge with Antarctica.3. Ocean Basins 
• Basically Indian Ocean can be divided into two major parts as follows:-

i) The Western Ocean Basin 

• It’s average depth of 3650 metre.
• It has many big Islands like. Madagascar Mauritius, Maldives etc.
• It has may sub basins:- (1) Oman Basin, (2) Arabian Basin, (3) Somalia Basin, (4) Mauritius Basin, (5) Mascarene Basin, (6) Agulhas-Natal Basin, (7) Atlantic-Indian-Antarctic Basin

ii) The Eastern Ocean Basin

• This  basin is much deeper than previous basin having average depth of 5500 metre.
• It has lesser number of Islands but some of the significant one are Srilanka, Andaman Nicobar Islands.
• In this basin continental shelf are lesser extensive only 160 km.
• It also has some sub basins:- (1) Eastern Indian – Antarctica Basin, (2) West Australian Basin and (3) Mid-Indian Ocean.

Ocean Deeps and Trenches

• There are very few number of Deeps and Trenches in Indian Ocean then Antarctica Ocean and Pacific Ocean. 
• About 80.1% of the Ocean consists of deep sea plains with depth ranging from 3600m to 5487m.
• Some important deeps and Trenches are Java-Sunda Trenche (7500 metre), Ob Trenche (6875m), Mauritius Trenche etc.

FAQs related Bottom Reliefs Of The Indian Ocean

Ques 1. What are the bottom reliefs of the Indian Ocean?

Answer: The bottom reliefs of the Indian Ocean encompass a diverse array of geological features on its seabed. These include underwater mountain ranges like the mid-oceanic ridges, oceanic trenches, seamounts, abyssal plains, and continental shelves.

Ques 2. How are the bottom reliefs of the Indian Ocean formed?

Answer: The formation of the bottom reliefs in the Indian Ocean is influenced by various geological processes. Mid-oceanic ridges result from the divergent movement of tectonic plates, leading to volcanic activity and the creation of new oceanic crust. Oceanic trenches are formed by the convergence of tectonic plates, while seamounts are volcanic underwater mountains. Abyssal plains are shaped by sedimentation over millions of years, and continental shelves are submerged extensions of the continental landmasses.

Ques 3. What is the significance of the bottom reliefs in the Indian Ocean?

Answer: The bottom reliefs of the Indian Ocean are of great importance for scientific research, marine biodiversity, and resource exploration.

• Mid-oceanic ridges provide insights into plate tectonics and the Earth’s geologic history.
• Oceanic trenches and seamounts are associated with unique ecosystems, hosting various marine species, some of which may be yet to be discovered.
• Abyssal plains play a role in carbon sequestration and climate regulation.
• Furthermore, the continental shelves in the Indian Ocean are rich in natural resources, supporting fishing industries and potential reserves of oil and gas.
• Understanding and conserving these bottom reliefs are essential for maintaining ecological balance and sustainable development in the region.

Read Also : Bottom Reliefs Of The Pacific Ocean