Alamagan
Mariana Volcanic Arc, United States. This page separates the permanent volcano catalogue, historical eruption records, and selective weekly activity reports.
- Coordinates
- 17.60° N, 145.83° E
- Elevation
- 744 m
- Last recorded eruption
- 870 CE
- Historical eruption records
- 4
- Primary type
- Stratovolcano
- Evidence
- Eruption Dated
- GVP database
- 5.4.0
- Catalogue revision
- Revision 2
Volcano profile
- Volcanic landform
- Composite
- Tectonic setting
- Subduction zone / Crustal thickness unknown
- Geologic epoch
- Holocene
- Major rock type
- Andesite / Basaltic Andesite
- Region
- Northwestern Pacific Volcanic Regions
- Subregion
- Mariana Volcanic Arc
Geological 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 S flank. Pyroclastic-flow deposits erupted about 1000 years ago have been dated, but reports of historical eruptions were considered invalid (Moore and Trusdell, 1993).
Separate activity dataset
Weekly volcanic activity reports
Smithsonian/USGS weekly reports are selective and preliminary. They are not a comprehensive list of all eruptions or volcanic activity.
No weekly report appears on this page. Absence from the weekly report does not establish an absence of volcanic activity.
Historical catalogue records
Eruption history
Dates can be approximate, incomplete, or BCE. These are historical catalogue observations, not a statement about present activity.
| Start | End | Activity | Confirmation | VEI | Evidence | Record |
|---|---|---|---|---|---|---|
| 1887-11-29 CE | Not supplied | Uncertain Eruption | Uncertain | Not supplied | Not supplied | GVP 18528Database 5.4.0 |
| 1864-01-16 CE (day uncertainty +/- 15) | Not supplied | Uncertain Eruption | Uncertain | Not supplied | Not supplied | GVP 18527Database 5.4.0 |
| 870 ±100 years CE | Not supplied | Confirmed Eruption | Confirmed | 4 | Isotopic: 14C (uncalibrated) | GVP 18526Database 5.4.0 |
| 540 ±75 years CE | Not supplied | Confirmed Eruption | Confirmed | Not supplied | Isotopic: 14C (uncalibrated) | GVP 18525Database 5.4.0 |
Source and attribution
Source: Data: Smithsonian Institution Global Volcanism Program, Volcanoes of the World.
View the original Smithsonian GVP recordGlobal Volcanism Program, 2026. Volcanoes of the World 5.4.0.
The GVP database is scientific documentation that changes as evidence is reviewed. Historical dates may be approximate or uncertain. This platform is not an official emergency-warning service.
Read the GVP terms of useData freshness
- Source updated
- Not supplied
- Retrieved
- 11 Oct 2026, 13:07 UTC
- GVP database version
- 5.4.0
- Catalogue revision
- 2
Source-update and retrieval times describe this catalogue record. Each weekly report carries its own publication date and preliminary status.