Louisville Ridge

The Louisville Ridge, often now referred to as the Louisville Seamount Chain, is an underwater chain of over 70 seamounts located in the Southwest portion of the Pacific Ocean. One of the longest seamount chains on Earth, it stretches some 4,300 km (2,700 mi) from the Pacific-Antarctic Ridge northwest to the Tonga-Kermadec Trench, where it subducts under the Indo-Australian Plate as part of the Pacific Plate. The chain's formation is best explained by movement of the Pacific Plate over the Louisville hotspot, although others have suggested that it formed by leakage of magma from the shallow mantle up through the Eltanin fracture zone, which it follows closely for some of its course.

Louisville Ridge
The Louisville Ridge stretches diagonally across this bathymetric map of the southwest Pacific Ocean.
Summit area	length:4,300 km (2,700 mi)
Location
Location	Southwest Pacific Ocean
Coordinates	38°16′S 167°55′W / 38.27°S 167.92°W / -38.27; -167.92
Geology
Type	Seamount chain
Volcanic arc/chain	Louisville hotspot
History
Discovery date	1972 (1964)

Depth-sounding data first revealed existence consistent with a seamount chain in 1972, although some of the seamounts had been described as a ridge in 1964 linked to the Eltanin fracture zone system, hence the name.

Geology

Louisville
  Seamounts

Wishbone
scarp

West
Wishbone 
scarp  

East
Wish-
bone
scarp

West
Wishbone 
scarp    

Tonga Trench

Osbourn Trough

 Kermadec
Trench

Hikurangi
Plateau

Chatham Rise

Immediate geological relationships of the chain of the Louisville seamounts. The violet line is the very deep trenches of the Kermadec-Tonga subduction zone with its arc volcanoes to the top left. Blue represents ocean depths of a kilometer or so and brown shades are shallower. The black line delineates the East Chatham Rise part of Zealandia continental crust.