On December 14, 1989, Redoubt Volcano, in south-central Alaska, erupted after 23 years of quiescence. Volcanic ash and floods generated by the eruption have caused significant damage to aircraft and temporarily curtailed oil production in Cook Inlet. The long-term effects of continued volcanic activity could be severe on the local economy. The two preliminary reports that follow, “The Eruption and Its Hazards” below and “Volcanic Ash and Aircraft” on the next page, describe the volcanic activity and some of the hazards of the first 6 weeks of the on-going eruption.