For many centuries people living on volcanoes have known that the outset of seismic activity is often a forerunner of a volcanic eruption. He identified the harmonic tremor which he indicated was a precursor of volcanic activity: "the characteristic feature of the ground mo­ tions preceding eruption is its continuity .

1 Introduction.- State of the Art in Volcanic Seismology.- 2 Seismic Activity and Other Precursors of Eruptions.- Short-Term Precursors of Natural Disastrous Events: A Statistical Assessment.- Deformation, Earthquakes and Mechanism of Activity of Klyuchevskoy Volcano.- Seismotectonics of the Mount Cameroon Volcanic Region, West Africa.- Volcanic Earthquakes at Merapi (Central Java) During the Lava Dome Building Beginning in October 1986.- Recent Seismicity at Vulcano Island (Southern Italy) and Adjacent Regions: Time Patterns and Periodicities.- Arenal Volcano (Costa Rica) Premonitory Seismicity.- Analysis of Seismic Activity Related to the 1982 Eruption of El Chichon Volcano, Mexico.- Coda Q Dependence on Time, Frequency and Coda Duration Interval at Mt. Etna, Sicily.- Measurements of Ground Movement on Mt. Etna, Sicily: A Systematic Plan to Record Different Temporal and Spatial Components of Ground Movement Associated with Active Volcanism.- 3 Modeling of Volcanic Earthquakes, Tremors and Long-Term Events.- A Seismic Model for the Source of Long-Period Events and Harmonic Tremor.- Volcanic Tremor: Seismic Signals of (Almost) Unknown Origin.- Preliminary Results from a Field Experiment on Volcanic Events at Kilauea Using an Array of Digital Seismographs.- Numerical Studies of the Dynamics of Fluid-Filled Cracks Placed in Series: A Model for Inharmonic Peaked Tremor Spectra.- Seismic Image of the Volcanic Tremor Source at Izu-Oshima Volcano, Japan.- Volcanic Tremor and Low-Frequency Earthquakes in Iceland.- Non-Double Couple Earthquake Focal Mechanisms and the Accretionary Tectonic Cycle.- Non-Double-Couple Earthquake Mechanisms in Volcanic Environments.- Nonlinear Inversion of S-Wave Polarization for Constraining the Source Mechanism of Small Earthquakes.- Seismic Activity at Stromboli (Southern Italy) for the Period 1983–1986.- Wave Polarization and Location of the Source of the Explosion Quakes at Stromboli Volcano.- 4 Tomography and Detection of Magma Chambers.- Seismological Detection and Delineation of Magma Chambers: Present Status with Emphasis on the Western USA.- Three-Dimensional Imaging of the Crust and Upper Mantle in the Long Valley-Mono Craters Region, California, Using Teleseismic P-Wave Residuals.- Three-Dimensional Inversion of Teleseismic Travel Time Residuals for Crust and Upper Mantle Velocity Structure in the Larderello Geothermal Field, Italy.- Physical Meaning of Coda Envelopes.- 5 Seismic Activity in Resurgent Calderas and Geothermal Fields.- Fracture Processes Induced by Forced Fluid Percolation.- Temperatures at the Base of the Seismogenetic Crust Beneath Long Valley Caldera, California, and the Phlegrean Fields, Caldera, Italy.- Seismic Investigation of the Campi Flegrei: A Summary and Synthesis of Results.- Seismological and Geodetic Data at Campi Flegrei (Southern Italy): Constraints on Volcanological Models.- Possibilities of Detecting Volcanic Seismic Sources at Campi Flegrei, Caldera.- Apparent Variation of Coda Q in Phlegraean Fields During the Bradyseismic Crisis of 1982–1984.- Dynamic Parameters of Volcaniclastic Soils and Rocks of Campi Flegrei (Naples, Italy).- A Thermo-Mechanical Model of the Inflation and Seismicity of Volcanic Calderas: An Application to the Campi Flegrei System.