The 2011 Alaska Interagency Operating Plan for Volcanic Ash Episodes is now available here: http://www.avo.alaska.edu/downloads/classresults.php?citid=3996 Photograph on the cover of the document is an ash, gas, and water vapor cloud from Redoubt Volcano as seen from Cannery Road in Kenai, Alaska, on March 31, 2009. Photograph by Neil Sutton, used with permission.
Credit: Image courtesy of the Alaska Interagency Operating Plan for Volcanic Ash Episodes.