Indian Ocean

                       INDIAN OCEAN 

* Body of water between Africa, Southern Ocean, Australia and Asia 

* Lies in eastern hemisphere 

* World 3rd largest Ocean 

* 29.8% of water on Earth surface 

* Area -7,05,60,000km²

* Named after India, which makes up much of its northern border 

* Known as Indian Ocean since 1515: earlier was called Eastern Ocean 

* Warmest Ocean in the world - lies near equator 

* Landlocked in Northern Hemisphere - does not extend to Artic waters - Closed Ocean 

* Ocean with maximum negative water balance and lowest Oxygen content - grater evaporation rate than its run off or precipitation influx 

* Madagascar - largest island in Indian Ocean and 4th largest in world 

* 40% of worlds offshore oil production comes from Indian Ocean 

Deepest Point:

* Sunda Trench ( popular name- Java Trench)

* Located - off the Southern Coast of Java * Depth -7,450 m

Delimiting of Indian Ocean:

* From Atlantic Ocean: 20° East Meridian, running south from Cape Agulhas

* From Pacific Ocean: meridian of 146° 49'E, running south from the southern most point of Tasmania 

* Northern most extent: including marginal season) : 30° north in the Persian Gulf 

Marginal Seas:

* Indian Ocean has some large marginal Seas 

* A marginal seas is a section of an Ocean partially enclosed by an island, a peninsula, or an archipelago ( group of islands)

* Marginal Seas are shallower than the Ocean and have close proximity to land.

* Marginal Seas in Indian Ocean are extremely important for trade - provide major sea routes that cannot middle East, Africa, East Asia, Europe and the Americas.

Marginal Indian Important Seas :

* Andaman asea( Gulf of Martban)

* Bay of Bengal 

* Andaman sea

* Arabian sea 

*Laccadive sea

* Gulf of Oman 

* Persian Gulf 

*Gulf of Aden 

* Red sea

* Mozambique channel

Submarine Fans:

* Submarine Fans are under water geological structures associated with large - scale sediment deposition.

* Indian Ocean contained the largest Submarine fans of the world Bengal fan and Indus fan

* The Bengal fan also known as the Ganges fan, is the largest Submarine fan on earth 

* Indus fan is the second largest fan system in the world between India, and Bangladesh and Andaman Islands.

* 40% of the sediment of Indian Ocean in Indus and Ganges fans.

* Immense load of suspended sediments from rivers emptying into Indian Ocean is the highest of the three Oceans.

* Nearly half of it comes from Indian subcontinent alone.

* Wharton Basin has the oldest sediments

Ridges: 

*Indian Ocean has active  spreading ridges 

* It includes:

- carlsberg Ridge 

- chagos - Laccadive Ridge 

- (central Indian Ridge)  south west India R

/(South east Indian Ridge)

-  Madagascar Ridge 

- 90° Ridge 

- Broken Ridge

Mid- Indian Ocean Ridge 

* Ocean floor of Indian Ocean is dominated by the Mid- Indian Ocean Ridge/ Central Indian Ocean Ridge.

* Separates African plate from Indo- Australian plate 

* The ridge from an inverted Y on the Ocean floor and subdivided by

- southeast Indian Ocean Ridge 

- southwest Indian Ocean Ridge 

Ninety East Ridge:

* Most striking is the aseismic ( Virtually earthquakes free) Ridge.

* Largest straight ridge - divides Indian Ocean into west and East Indian Ocean 

* First discovered in 1962

* Extent between latitudes 33*S and 17*N

* Runs northward along the 90* E merridian( hence its name) from the Broken Ridge 

* Total length - 5,000km average width- 200km

 Rodrigues Triple Junction:

* Geologic  triple junction in Southern Indian Ocean where three tectonic plates meet: African plate, into- Australian plate and Antarctic plate.

- Central Indian Ridge: including the Carls berg Ridge, separating African plate from Indian plate.

* South west Indian Ridge, separating  African plate from Antarctic plate.

* Southeast Indian Ridge separating Australian plate from Antarctic plate.

Important Straits:

* Sea lanes  in the Indian Ocean are considered among the most strategically important lanes for the world Trade.

" More than 80% of the worlds seaborne oil trade is through Indian Ocean and it's vital choke points.

* Of which 40% passing the strait of Hormuz 

*35% passes through strait of Malacca 

*8% through Bab el- mandab strait.

Indian Ocean Garbage Patch:

* An Indian Ocean GARBAGE PATCH Ride the southern Indian Ocean Gyre( any large system of circulating Ocean current is called a Gyre)

* This Vortex of plastic garbage constantly circulates the Ocean from Australia to Africa, down the Mozambique channel, and back to Australia in a period of six years.

* Plastic in it break down to small particles to constituent polymers.

Flora and Fauna:

* Coral Reefs, sea grass beds, and mangrove forests are the most productive ecosystems of the Indian Ocean.

* 50% of worlds mangroves in the Indian Ocean 

* Warm Ocean less phytoplankton (except along the northern fringes and in a few scattered spots) limited sea life.

* Endangered species include dugong, whales, seablions, turtles.

* The western Indian Ocean hosts one of the largest concentration of phytoplankton blooms in summer, due to the strong monsoon winds.

* A study on the phytoplankton changes in the Indian Ocean indicates a decline of up to 20% in the marine plankton in the Indian Ocean, during the past six decades.

Natural Disaster:

* Two of the most devastating natural disasters.

- 2004: Tsunami - killed 2,28,000 people.

- cyclone Nargis - Myanmar in 2008  ( Killed 138,300 people)