Geography of Nauru

Nauru is a tiny phosphate rock island located in the South Pacific Ocean south of the Marshall Islands in Oceania. It is only 53 km south of the Equator at coordinates 0°32′S 166°55′E. Nauru is one of the three great phosphate rock islands in the Pacific Ocean — the others are Banaba (Ocean Island) in Kiribati and Makatea in French Polynesia.

Its land area is 21 km² and it has a 30 km coastline. Maritime claims are a 200 nautical mile (370 km) exclusive fishing zone, and a 12 nautical mile (22 km) territorial sea.

The climate is tropical with a monsoonial rainy season from November to February.

A sandy beach rises to the fertile ring around raised coral reefs. The raised phosphate plateau ('Topside') takes up the central portion of the island. The highest point is 200 ft (61 m) above sea level along the plateau rim.

Nauru's only natural resources are phosphates, formed from guano deposits by seabirds over many thousands of years.

Due to being surrounded by corals and sandy beaches, the island houses no natural harbours, nor any rivers or substantial lakes.

Geology of Nauru

An aerial image of Nauru in 2002 from the U.S. Department of Energy's Atmospheric Radiation Measurement Program. Regenerated vegetation covers 63% of land that was mined.

Nauru is positioned in the Nauru Basin of the Pacific Ocean, on a part of the Pacific Plate that formed at a mid oceanic ridge at 132 Ma. From mid Eocene (35mya) to Oligocene times a submarine volcano built up over a hotspot, and formed a seamount composed of basalt. The seamount is over 4300 meters high. This hotspot was simultaneous with a major Pacific Plate reorganisation. The volcano was eroded to sealevel and a coral atoll grew on top to a thickness of about 500 meters. Coral near the surface has been dated from 5 Mya to 0.3 Mya. The original limestone has been dolomitised by magnesium from sea water. The coral was raised above sea level about 30 meters, and is now a dolomite limestone outcrop which was eroded in classic karst style into pinnacles up to 20 meters high. To at least a depth of 55 meters below sea level, the limestone has been dissolved forming cavities, sinkholes and caves. Holes on the topside of the island were filled up by a phosphate layer up to several meters thick.

Anibare Bay was formed by the underwater collapse of the east side of the volcano. Buada Lagoon was formed by solution of the limestone when the sea level was lower, followed by collapse.

Nauru is moving at 104 mm per year to the north west along with the Pacific Plate.

Freshwater can be found in Buada lagoon, and also in some brackish ponds at the escarpment base in Ijuw and Anabar in the northeast. There is an underground lake in Moqua Cave in the southeast of the island.

Environmental issues

• Periodic droughts, limited natural fresh water resources (roof storage tanks collect rainwater, but mostly dependent on a single, aging desalination plant)
• Extreme soil conditions are caused by high alkalinity, high phosphate levels and low potassium. Iron, manganese, copper, molybdenum and zinc are rendered unavailable to plants. Combined with thin or damaged soils this causes low fertility.
• Intensive phosphate mining during the past 90 years has left the central 90% of Nauru a wasteland and threatens limited remaining land resources.

Nauru is party to the international environmental agreements on biodiversity, climate change, desertification, law of the sea and marine dumping.

See also

• List of cities in Nauru