The Peruvian city of Arequipa has built up at the base and up the lower slopes of El Misti. In a paper appearing in the December 2001 issue of The Geological Society of America Bulletin, a group of scientists led by Jean-Claude Thouret is predicting a major eruption, the first since the 1400s. His prediction is based in part on layers of ash dated every 500-1500 years. the most recent reports of activity are from the 80s. There are no evacuation plans, according to the local civil defense. Some of the data behind their work is here.