The following HTML text is provided to enhance online
readability. Many aspects of typography translate only awkwardly to HTML.
Please use the page image
as the authoritative form to ensure accuracy.
FIGURE 1.1 The summit region of Nevado del Ruiz volcano subsequent to the November 13, 1985 eruption. Note vapor cloud issuing from the summit crater and the tephra blanket overlying the glacial ice cap. (Photograph by D. Herd, USGS.)