By the year 2000, the population worldwide at risk from volcanic hazards is likely to increase to about half a billion. Reviews of selected case histories of recent volcanic disasters demenostrate that effective communication - between scientists, civil authorities, news media and population - are essential to reduce volcanic risks.

I Volcano Monitoring: Techniques and Case Histories.- A Review of Volcano Geophysics and Volcano-Monitoring Methods.- New Methods and Future Trends in Seismological Volcano Monitoring.- Seismic Monitoring and Eruption Forecasting of Volcanoes: A Review of the State-of-the-Art and Case Histories.- Ground-Deformation Methods and Results.- Microgravity Monitoring.- Chemical Characters of the Gaseous Phase in Different Stages of Volcanism: Precursors and Volcanic Activity.- Chemical Composition of Volcanic Gases.- Satellite Monitoring of Volcanoes.- Detection of Explosive Eruptions and Regional Tracking of Volcanic Ash Clouds with Geostationary Meteorological Satellite (GMS).- The Integrated Mobile Volcano-Monitoring System Used by the Volcano Disaster Assistance Program (VDAP).- II Modeling of Monitoring Data and Eruptive Phenomena.- Ground Deformation Modeling in Volcanic Areas.- Physical Modeling of Collapsing Volcanic Columns and Pyroclastic Flows.- Modeling of Tephra Fallout from Explosive Eruptions.- Physical Modeling of Eruptive Phenomena: Lahars.- Patterns and Predictability in the Emplacement of Subaerial Lava Flow and Flow Fields.- III Volcano Hazards and Risk Assessment.- Hazards of Large Volcanic Debris Avalanches and Associated Eruptive Phenomena.- Hazardous Crater Lakes.- Long-Term Probabilistic Analysis of Future Explosive Eruptions.- Quantitative Reconstruction of Recent Volcanic Activity: A Contribution to Forecasting of Future Eruptions.- Volcanic Hazards Risk Assessment.- IV Volcanic Emergency Management.- Mitigation Measures and Preparedness Plans for Volcanic Emergencies.- The Management of Volcano Emergencies: Nevado del Ruiz.- The Problem of Volcanic Unrest: The Campi Flegrei Case History.- Volcanic Emergency Management in Japan: Case Histories of Izu-Oshima and Unzen.- The Narrow Margin of Successful Volcanic-Risk Mitigation.