EarthMapped Mid-ocean ridges
World map of mid-ocean ridges and continental riftsAFRICANANTARCTICSOMALIINDIANAUSTRALIANEURASIANNORTH AMERICANSOUTH AMERICANNAZCAPACIFICARABIANSUNDACARIBBEANCOCOSOKHOTSKJUAN DE FUCAPHILIPPINE SEAAMURSCOTIAYANGTZE

Mid-Ocean Ridge Map

The mid-ocean ridge is an underwater mountain range that forms where tectonic plates spread apart. PB2002 maps 67,367 km of spreading ridge; NOAA puts the whole system at nearly 65,000 km.

  • Mid-ocean ridge. An underwater mountain range that forms along divergent plate boundaries, where new ocean floor is made. Source
  • Rift. A valley where the crust is being pulled apart, such as the East African Rift, which may in time become a new ocean. Source

Data source: PB2002 plate model, Bird (2003), converted by Hugo Ahlenius, Nordpil, ODC-By 1.0. Download: GeoJSON .

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What the map shows

A mid-ocean ridge Mid-ocean ridge. An underwater mountain range that forms along divergent plate boundaries, where new ocean floor is made. Source forms along a divergent boundary on the sea floor. NOAA describes the system as nearly 65,000 km long. The solid red lines are every step PB2002 classes as an oceanic spreading ridge. The dashed lines are continental rifts Rift. A valley where the crust is being pulled apart, such as the East African Rift, which may in time become a new ocean. Source , where the same pulling apart happens on land.

Key facts

  1. The mid-ocean ridge system is nearly 65,000 km long, and the top of the ridge lies on average about 2,500 m below the sea surface. NOAA Ocean Exploration, What is the mid-ocean ridge?
  2. PB2002 maps 67,367 km of oceanic spreading ridge, 4% more than NOAA's figure. Each source draws and measures the ridge its own way. Bird (2003)
  3. 61 pairs of plates are separated by a spreading ridge. The longest is African and South American, at 8,169 km.
  4. The fastest spreading pair is Nazca and Pacific, at a mean 14.1 cm/yr. Among pairs with over 500 km of ridge, North American and South American is slowest, at 0.2 cm/yr.
  5. The Mid-Atlantic Ridge spreads 2 to 5 cm a year and has a deep rift valley along its crest. The East Pacific Rise spreads 6 to 16 cm a year and has no rift valley. NOAA Ocean Exploration, What is the mid-ocean ridge?
  6. Iceland straddles the Mid-Atlantic Ridge, so the spreading can be studied on land there. USGS, Understanding plate motions

Spreading ridges by plate pair

Every pair of plates with a spreading ridge between them in PB2002, longest first. Sort by any column.

Oceanic spreading ridges in PB2002, by plate pair
PlatesLength (km)Mean spreading (cm/yr)Top spreading (cm/yr)
African and South American 8,169 3.2 3.4
Australian and Antarctic 7,457 6.8 7.2
North American and Eurasian 7,324 1.7 2.3
Pacific and Antarctic 5,322 7.6 9.5
Nazca and Pacific 3,296 14.1 15.1
Somali and Antarctic 3,271 1.1 1.4
North American and African 2,956 2.3 2.5
Somali and Indian 2,487 3.0 3.6
Cocos and Nazca 2,062 5.3 6.6
Australian and Somali 1,763 4.1 4.9
Cocos and Pacific 1,743 10.0 12.6
African and Antarctic 1,475 1.4 1.4
Philippine Sea and Mariana 1,294 3.5 5.6
Antarctic and Nazca 1,291 5.7 5.8
Somali and Arabian 1,101 2.4 2.8
Pacific and Juan de Fuca 1,073 5.6 5.6
Indian and Australian 1,059 0.3 0.5
Kermadec and Australian 1,006 3.3 5.1
North American and South American 992 0.2 0.3
Caroline and Philippine Sea 754 0.4 0.8
Eurasian and African 633 0.4 0.5
Sandwich and Scotia 620 7.2 8.1
Easter and Pacific 613 8.4 13.7
Australian and Conway Reef 599 3.3 5.5
Conway Reef and New Hebrides 599 8.3 11.8
Antarctic and South American 569 1.7 1.8
Australian and Woodlark 549 3.1 4.0
Juan Fernandez and Pacific 499 13.3 20.2
New Hebrides and Pacific 497 1.4 2.3
Easter and Nazca 481 6.9 11.5
Tonga and Australian 467 6.1 9.3
Scotia and Antarctic 437 1.1 1.2
Balmoral Reef and New Hebrides 423 3.0 3.9
Sunda and Burma 403 3.7 4.5
Pacific and Balmoral Reef 374 2.2 2.2
North American and Pacific 348 4.7 4.9
Rivera and Pacific 316 6.5 8.0
Indian and Arabian 282 0.7 0.7
Niuafo'ou and Australian 259 8.4 9.2
Juan Fernandez and Nazca 244 4.5 8.2
Tonga and Niuafo'ou 190 10.4 12.6
Pacific and Niuafo'ou 175 13.8 13.9
Futuna and Pacific 175 4.4 4.9
Galapagos and Pacific 167 11.6 12.3
Galapagos and Nazca 167 3.2 3.9
Aegean Sea and Anatolia 134 1.9 1.9
Manus and South Bismarck 133 10.2 15.6
Scotia and South American 120 0.5 0.5
Juan Fernandez and Antarctic 119 5.9 7.4
Caribbean and North American 119 1.7 1.7
Galapagos and Cocos 106 0.9 1.1
North Bismarck and Manus 100 4.7 8.4
New Hebrides and Australian 85 12.8 12.9
Amur and Okinawa 77 0.4 0.5
Pacific and Caroline 71 1.1 1.1
Niuafo'ou and Futuna 60 10.9 11.1
Balmoral Reef and Australian 58 6.9 6.9
Nazca and Panama 58 4.0 4.0
Yangtze and Okinawa 56 4.5 4.5
Woodlark and Birds Head 54 6.1 6.1
Pacific and Australian 7 2.9 2.9

Data source: PB2002 plate model, Bird (2003), converted by Hugo Ahlenius, Nordpil, ODC-By 1.0. Download: GeoJSON .

Longest unbroken ridge segments

Longest continuous spreading ridge segments
PlatesLength (km)Mean spreading (cm/yr)Near
North American and Eurasian 1,251 1.0 84°N, 109°E
North American and Eurasian 1,014 1.5 74°N, 9°E
North American and South American 992 0.2 16°N, 51°W
Caroline and Philippine Sea 754 0.4 4°N, 133°E
Indian and Australian 725 0.3 7°S, 72°E
Australian and Antarctic 623 6.9 43°S, 92°E
African and South American 592 3.3 43°S, 16°W
Australian and Antarctic 589 7.0 50°S, 136°E
Cocos and Nazca 587 6.0 1°N, 88°W
Cocos and Pacific 522 11.5 6°N, 103°W

Data source: PB2002 plate model, Bird (2003), converted by Hugo Ahlenius, Nordpil, ODC-By 1.0.

Transform faults cut the ridge into short pieces, so the longest unbroken segments are much shorter than the ridge between a pair of plates. See them on the transform boundary map, compare the subduction zones map, or read why tectonic plates move.

Print this map Plate boundaries worksheet. Label the boundary types, with an answer key

Glossary

Mid-ocean ridge
An underwater mountain range that forms along divergent plate boundaries, where new ocean floor is made. Source
Rift
A valley where the crust is being pulled apart, such as the East African Rift, which may in time become a new ocean. Source
Divergent boundary
Plates pull away from each other and new crust forms between them. Source
Transform boundary
Plates slide horizontally past each other. Crust is neither made nor destroyed. Source
Relative plate velocity
How fast one plate moves compared with its neighbor across a boundary, in millimeters per year. Source

All terms in the glossary

Mid-ocean ridge FAQ

What is a mid-ocean ridge?
An underwater mountain range that forms where two plates move apart. Magma rises into the gap, cools and becomes new ocean floor, so the ridge is a divergent plate boundary.
How long is the mid-ocean ridge?
NOAA gives nearly 65,000 km for the whole system. The PB2002 model, drawn on this map, has 67,367 km of oceanic spreading ridge.
Which mid-ocean ridge spreads fastest?
The East Pacific Rise, at 6 to 16 cm a year according to NOAA. In PB2002 the fastest pair is Nazca and Pacific, at a mean 14.1 cm/yr.
Is the Mid-Atlantic Ridge the same as the mid-ocean ridge?
It is one part of it. The Mid-Atlantic Ridge runs down the Atlantic Ocean and is one section of the global ridge system shown on this map.
What are the dashed lines on the map?
Continental rifts, where a plate is splitting on land, such as the East African Rift. They are divergent boundaries too, but they are not mid-ocean ridges.

Sources: NOAA Ocean Exploration, What is the mid-ocean ridge?; USGS, Understanding plate motions; Bird (2003) for lengths and speeds.