Low-level unrest continued at Pagan during 27 December 2013-2 January 2014; seismicity remained above background levels. A robust steam-and-gas plume was occasionally visible in web camera images during the reporting period. A small explosion was detected at about 0145 on 28 December. It may have produced a diffuse ash emission, but the webcam was not in operation at the time to verify. The Aviation Color Code remained at Yellow and the Volcano Alert Level remained at Advisory.

Geological Summary. 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. North Pagan at the NE end of the island rises above the flat floor of the northern caldera, which may have formed less than 1,000 years ago. South Pagan is a stratovolcano with an elongated summit containing four distinct craters. Almost all of the recorded eruptions, which date back to the 17th century, have originated from North Pagan. The largest eruption during historical time took place in 1981 and prompted the evacuation of the sparsely populated island.

Source: Emergency Management Office of the Commonwealth of the Mariana Islands and United States Geological Survey Volcano Hazards Program