Anatahan Volcano in the central Mariana Islands began releasing plumes of ash and steam in early February 2008, continuing a pattern of intermittent activity from the previous December. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite captured this image on February 6, 2008. In this image, a diffuse pale gray plume blows westward away from the volcanic island and over the Pacific Ocean. Toward the west, the plume fans out and becomes thinner. When pollutants from a volcano mix with oxygen and water in the presence of sunlight, vog, or volcanic smog, can result. The diffuse plume in the west could consist partly of vog.
Anatahan is a 9-kilometer- (5.6-mile-) long island. The island is a stratovolcano composed of alternating layers of solidified ash, hardened lava, and rocks ejected by previous eruptions. The first historical eruption of Anatahan occurred in May 2003, and that explosive eruption formed a new crater inside the island’s eastern caldera.