Report on Pagan (United States) — 15 April-21 April 2009
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 15 April-21 April 2009
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2009. Report on Pagan (United States). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 15 April-21 April 2009. Smithsonian Institution and US Geological Survey.
18.13°N, 145.8°E; summit elev. 570 m
All times are local (unless otherwise noted)
Based on reports from the Washington VAAC, the USGS stated that on 15 April intermittent plumes of steam from Pagan rose to an altitude of 1.8 km (6,000 ft) a.s.l. and drifted 37 km W. Observers on a ship reported that a white plume "with some black" rose 1.8 km (5,700 ft) from the volcano. On 16 April a diffuse plume drifted 85 km W. USGS raised the Aviation Color Code to Yellow and the Volcano Alert Level to Advisory. The next day fishermen again reported a plume.
Geologic Background. 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.