Maug Islands
Find U.S. Volcano
Three small elongated islands up to 2.3 km long mark the northern, western, and eastern rims of a largely submerged 2.5-km-wide caldera.
Quick Facts
Location: Commonwealth of the Northern Mariana Islands
Latitude: 20.02° N
Longitude: 145.22° E
Elevation: 227 (m) 745 (f)
Volcano type: Stratovolcano
Composition: Basalt - Dacite
Most recent eruption: Unrest in the Holocene
Threat Potential: Low/Very Low*
*based on the National Volcano Early Warning System
Summary
Three small elongated islands up to 2.3 km long mark the northern, western, and eastern rims of a largely submerged 2.5-km-wide caldera. The highest point of the Maug Islands reaches only 227 m above sea level; the submerged southern notch on the caldera rim lies about 140 m below sea level. The caldera has an average submarine depth of about 200 m and contains a twin-peaked central lava dome that rises to within about 20 m of the sea surface. The Maug Islands form a twin volcanic massif with Supply Reef, about 11 km N. The truncated inner walls of the caldera on all three islands expose lava flows and pyroclastic deposits that are cut by radial dikes; bedded ash deposits overlie the outer flanks of the islands. No eruptions are known since the discovery of the islands by Espinosa in 1522. The presence of poorly developed coral reefs and coral on the central lava dome suggests a long period of general quiescence, although it does not exclude mild eruptions. A 2003 NOAA expedition detected possible evidence of submarine geothermal activity. From the Smithsonian Global Volcanism Program.
Publications
Volcanic hazards in the Pacific U.S. Territories
2018 update to the U.S. Geological Survey national volcanic threat assessment
When erupting, all volcanoes pose a degree of risk to people and infrastructure, however, the risks are not equivalent from one volcano to another because of differences in eruptive style and geographic location. Assessing the relative threats posed by U.S. volcanoes identifies which volcanoes warrant the greatest risk-mitigation efforts by the U.S. Geological Survey and its partners. This update
Volcanic investigations in the Commonwealth of the Northern Mariana Islands, April to May 1994
A team of U.S. Geological Survey geologists, a seismologist, and technicians gathered new geologic, seismic, and deformation data in the Commonwealth of the Northern Mariana Islands (CNMI). Nine volcanic islands on the active East Mariana Ridge north of Saipan were examined between April 20 and May 3, 1994. In addition, a new radio-telemetry seismic station was installed on the island of Agrihan (