Volcanic Seismology

For many centuries people living on volcanoes have known that the outset of seismic activity is often a forerunner of a volcanic eruption. This understand­ ing allowed people living close to the sites of the Mt. Nuovo 1538 eruption at Campi Flegrei, Italy, and of the Mt. Usu 1663 eruption, in Hokkaido, Japan (to quote only two examples) to flee before the eruptions started. During the second half of the 19th century seismographs were installed on some volcanoes, and the link between seismic and eruptive activity started to be assessed on a firmer scientific basis. The first systematic observations of the correlations existing between seismic activity and volcanic eruptions were probably those carried out at Mt. Vesuvius by Luigi Palmieri in 1856. Palmieri was the Director of Osservatorio Vesuviano and built an electromagnetic seismograph with the aim of "making visible the smallest ground motions by recording them on paper and indicating direction, intensity and duration". He was able to show the relationship between earthquakes and the different phases of volcanic activity. 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 . . . (before the eruption of 1861) the electromagnetic seismograph began to show a continuous tremor". The Palmieri seismograph was also utilized in Japan until 1883, when it was replaced by the new Gray-Milne seismographs, and, later, by the Omori in­ struments.

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.