The Moderate Resolution Imaging Spectroradiometer (MODIS) sensor on NASA's Terra and Aqua satellites observed plumes on Dec. 20 and Dec. 22. Meanwhile, the Ozone Monitoring Instrument (OMI) on NASA's Aura satellite detected elevated levels of sulfur dioxide, further indicating an eruption.
But the activity in the Red Sea included more than an eruption. By Dec. 23, what looked like a new island appeared in the region. The Advanced Land Imager (ALI) on NASA's Earth Observing-1 (EO-1) satellite captured these high-resolution, natural-color images on Dec. 23, 2011 (top), and Oct. 24, 2007 (bottom).
The image from December 2011 shows an apparent island where there previously had been an unbroken water surface. A thick plume rises from the island, dark near the bottom and light near the top, perhaps a mixture of volcanic ash and water vapor.