Pagan Island, the largest and one of the most active of the Mariana Islands volcanoes, consists of two
stratovolcanoes connected by a narrow isthmus. Both North and South Pagan stratovolcanoes were constructed
within calderas, 7 and 4 km in diameter, respectively. The 570-m-high Mount Pagan at the NE end of the island
rises above the flat floor of the northern caldera, which may have formed less than 1000 years ago.
South Pagan is a 548-m-high stratovolcano with an elongated summit containing four distinct craters.
Almost all of the historical eruptions of Pagan, which date back to the 17th century, have originated from
North Pagan volcano. The largest eruption of Pagan during historical time took place in 1981 and prompted the
evacuation of the sparsely populated island.
December 12th, 2011
During 4-5 December, residents 3 km SW of Pagan reported ashfall that accumulated in their camp at a rate
of about 6.4 mm per day. They also described a plume from the summit that rose to an altitude of 640 m
(2,100 ft) a.s.l. and a sulfur smell that occasionally wafted through their camp. Based on satellite imagery, the
Washington VAAC reported a gas-and-ash plume that drifted mainly W on 5, 6, and 8 December.
Satellite imagery showed no further activity through 11 December.