Alamagan
Find U.S. Volcano
Alamagan is the emergent summit of a large stratovolcano in the central Mariana Islands with a roughly 350-m-deep summit crater east of the center of the island.
Quick Facts
Location: Commonwealth of the Northern Mariana Islands
Latitude: 17.6° N
Longitude: 145.83° E
Elevation: 744 (m) 2,441 (f)
Volcano type: Stratovolcano
Composition: Andesite - Basalt
Most recent eruption: 870 CE
Threat Potential: Moderate*
*based on the National Volcano Early Warning System
Summary
Alamagan is the emergent summit of a large stratovolcano in the central Mariana Islands with a roughly 350-m-deep summit crater east of the center of the island. The exposed cone is largely Holocene in age. A 1.6 x 1 km graben cuts the SW flank. An extensive basaltic-andesite lava flow has extended the northern coast of the island, and a lava platform also occurs on the south flank. Pyroclastic-flow deposits erupted about 1000 years ago have been dated, but reports of historical eruptions were considered invalid. 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 (