Location: 16.4N, 145.7E

Elevation: 788m (2,585 ft.)

Area 32 sq. km

Island type: high volcanic cone, dissected with ravines and ridges

Anatahan is a small island (6 by 2 miles, 9 by 3-km) made of overlapping calderas. It is located 75 nautical miles north of Saipan and has an area of 12.5 square miles. The volcano has two peaks with a grass covered flat field. The island's steep slopes are furrowed by deep gorges covered by high grass. The coastline is precipitous. Landing beaches are on the north and the west shore and a small sandy beach on the southwest shore.

Anatahan has no known historical eruptions. Recent activity includes a period of felt earthquakes that began on March 30, 1990. Felt earthquakes continued for two more days. An over flight revealed that the crater Lake in the east part of the main caldera had become turbulent and changed color. The intensity of fumaroles had increased and the smell of rotten eggs was reported. The volcanic unrest caused the evacuation of the island's 23 residents. A field investigation found a deposit from a phreatagmatic eruption that is younger than human occupation of the island. Overflows of hot acidic water from the lake had killed a large area of vegetation. Tilt on the flank of the volcano had not changed. Electronic distance measurements measured extension across the volcano up to about 3.5 inches (91 mm). Volcanologists returned to the island in late June. During their 2-day visit, no earthquakes larger than magnitude 2.5 were recorded. Measurements of deformation revealed no significant changes since April. However, the crater lake had disappeared and was replaced by several pits and the area was vigorously steaming. Swarms of earthquakes occurred again at Anatahan in late May to early June of 1993. The island was declared off limits. No eruption occurred.

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Natural threats: cyclones

Human impact: disturbed by Japanese colonists and WWII military activities; small resident population.

Ecosystems: rainforest, grassland on upper slopes

Special features: crater with grassy floor and intermittent lake; forest of some conservation interest.

Species of conservation interest
Megapodius laperouse laperouse (Marianas Megapode) group endemic subspecies, Rare (RDB), possibly present

Natural conservation status 1. 
Ecosystem richness 1. 
Species richness 1. 
Economic pressure 0. 
Human threat 1. 
Natural vulnerability 12. 
Practicality of conservation action 1. 
Reliability of data 1. 
Human Impact 1. 
Conservation Importance 13 .

Uracas  Maug   Ascuncion  Agrigan   Pagan  Alamagan   Guguan  Sarigan   Anatahan  Medinilla

Saipan  Tinian   Aguihan  Rota   Guam

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