Alamagan Volcano | John Seach


Mariana Islands

17.60 N, 145.83 E
summit elevation 744 m

Alamagan is a large stratovolcano in the central Mariana Islands. The volcanic island is 9.5 km x 6 km in size. It contains a 2 km wide caldera.

An large basaltic-andesite lava flow has extended the northern coast of the island, and a lava platform also occurs on the southern flank.

2009 Super typhoon
Super typhoon Choi-Wan passed directly over Almagan island at 4pm on 15th September 2009. Maximum wind speeds reached 150 miles per hour. There were 15 people living on the island, but no injuries or damage was reported.

2007 Earthquake
There was a magnitude 7.2 earthquake on 31 October 2007, with epicentre 43 km WNW of the island.

1999 Evacuations
Five residents were evacuated from Alamagan Island by helicopters after an increase in fumarolic activity was noted at the volcano. The increase in fumarolic activity was related to rainfall after a dry period, and there were no other signs of unrest at the volcano.

Further reading
Moore, Richard B., et al. "Volcanologic investigations in the Commonwealth of the Northern Mariana Islands, May 1992." US Geological Survey Open-File Report (1993): 93-541.

Alamagan Volcano Eruptions

1887?, 1864?, 870 AD ± 100, 540 AD ± 75