For three years, North Pagan Volcano has emitted intermittent volcanic plumes. Composed mainly of steam, the plumes also contained other volcanic gases (such as sulfur dioxide) and occasionally small amounts of ash. By mid 2011, Pagan’s activity was nearly continuous, and NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS), carried on both the Terra and Aqua satellites, detected a plume almost every time there was a clear view. (Satellites provide the only reliable observations of Pagan, as the island has been uninhabited since a major eruption forced residents to leave in 1981.)
This natural-color image of Pagan Island from May 7, 2012, was collected by the MODIS instrument on the Terra satellite. A volcanic plume blows westward from the summit of North Pagan Volcano. The plume’s blue tint suggests the presence of sulfur dioxide. Several hours after this image was acquired, the Ozone Monitoring Instrument (OMI) on the Aura satellite detected elevated levels of sulfur dioxide just west of the volcano.