HR: 1340h
AN: V33A-0672    [Abstracts]
TI: Non-Double Couple Earthquakes in Volcanic and Geothermal Areas
AU: * Guidarelli, M
EM: mguidar@dst.units.it
AF: Department of Earth Sciences - University of Trieste, Via E. Weiss 4, Trieste, 34127 Italy
AU: Panza, G F
EM: panza@dst.units.it
AF: Department of Earth Sciences - University of Trieste, Via E. Weiss 4, Trieste, 34127 Italy
AU: Panza, G F
EM: panza@dst.units.it
AF: The Abdus Salam International Centre for Theoretical Physics, Strada Costiera, 11, Trieste, 34014 Italy
AB: Volcano seismology is the study of earthquakes of volcanic origin. With the availability of broadband seismometers, volcano seismology has become a powerful tool to obtain information about the dynamics of volcanic source mechanisms and then to investigate the internal conditions of a volcano and the stress field acting on it. A fundamental goal of volcano seismology is to understand the nature and dynamics of seismic sources associated with the injection and transport of magma and related hydrothermal fluids. The knowledge of the processes acting in a volcano is critical to the assessment of the eruptive behaviour, with great importance in monitoring volcanic activity and estimating volcanic hazard. Most of the seismological methodologies for the analysis of seismic sources are based on the assumption that the earthquakes are caused by shear fracture, for which the equivalent force system is a pair of perpendicular force couples without a resulting moment, or "double couple" (DC). The development of seismological methodologies leads the seismologists to observe departures from the DC model for many earthquakes. These earthquakes with non-DC mechanisms are found especially in volcanic and geothermal areas. The methodologies for the inversion of the complete seismic waveform are one of the most suitable tools for the retrieval of the source mechanisms and the determination of non-DC components. In particular, the methodology proposed by Sileny et al. (1992) has been successfully applied in different tectonic settings, especially in volcanic environments. We discuss here moment tensor solutions from waveform inversions in Italian volcanic and geothermal areas (Campi Flegrei, Vesuvio, Mt Etna, Larderello), obtained using the methodology proposed by Sileny et al. (1992), and we highlight the presence of non-DC earthquake components, i.e. isotropic and CLVD components. We review some results and compare the solutions obtained in the four different areas trying to evaluate the possible mechanisms that generate the seismic activity in the areas.
DE: 8419 Volcano monitoring (7280)
DE: 8488 Volcanic hazards and risks
DE: 8494 Instruments and techniques
SC: Volcanology, Geochemistry, Petrology [V]
MN: Fall Meeting 2005