- Volcanic History 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 south flank. Pyroclastic-flow
deposits erupted about 1000 years ago have been dated, but
reports of historical eruptions were considered invalid (Moore
and Trusdell, 1993). From the Smithsonian Global Volcanism
Program. - Location: Mariana Islands, Mariana Islands Elevation:
744 m Recent Eruption: 1000 years ago - Hazard Assessments:
Sako, M. K.; Trusdell, F. A.; Koyanagi, R. Y.; Kojima, George;
Moore, R. B., 1995, Volcanic investigations in the Commonwealth
of the Northern Mariana Islands, April to May 1994, USGS Open-
File Report 94-705. - Link to monitoring data: NMI Web Site
Volcanic Alert Level: UNASSIGNED Avia