Alamagan
Stratovolcano in United States
Key Facts
Elevation
744 m (2,441 ft)
Type
Stratovolcano
Location
17.600°, 145.830°
Region
Mariana Volcanic Arc
Rock Type
Andesite / Basaltic Andesite
Tectonic Setting
Subduction zone
Location
Loading map...
Overview
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).
Volcanic Hazards & Risk Assessment
Primary Hazards
- Pyroclastic flows
- Lava flows
- Volcanic bombs and ballistics
- Lahars and mudflows
Risk Level
Geological Composition & Structure
Rock Types
Tectonic Setting
Age & Formation
Eruption Statistics & Analysis
| Metric | Value | Global Ranking | Significance |
|---|---|---|---|
| Total Recorded Eruptions | Unknown | Low | Moderately active volcano |
| Maximum VEI | VEI Unknown | Minor | Local impact potential |
| Recent Activity | 1156 years ago | Historical | Historically active |
Monitoring & Alert Status
Monitoring Networks
Current Status
Nearby Volcanoes in Northwestern Pacific Volcanic Regions
Quick Info
- •Smithsonian ID: 284180
- •Evidence: Eruption Dated
- •Epoch: Holocene
About the Photo
Alamagan, seen here from the W with two peaks on either side of a roughly 350-m-deep summit crater, is the emergent summit of a large submarine volcano. The exposed cone is largely Holocene in age and the SW flank contains a 1 x 1.6 km graben. Pyroclastic flow deposits have been dated at about 1,000 years old.
Photo by Norm Banks, 1981 (U.S. Geological Survey).
Authority Sources
Related Volcanoes
Basic Information
This page shows basic data from the Smithsonian Global Volcanism Program. For more detailed information, visit the official Smithsonian page.