Hold the left mouse button down as you drag the slider above the image (or use the arrow buttons) to fade between the GOES-8 visible image and the corresponding GOES-8 IR difference product and 6.7 micron IR ("water vapor") images at 13:15 UTC on 07 October 1999. At this time (about 1 hour after the eruption), portions of the volcanic ash plume can bee seen moving both westward and eastward away from the capitol city of Quito (station identifier SEQU).