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| Titel |
A model for seismicity rates observed during the 1982-1984 unrest at Campi Flegrei Caldera (Italy). |
| VerfasserIn |
Maria Elina Belardinelli, Andrea Bizzarri, Giovanni P. Ricciardi, Giovanna Berrino |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250038657
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| Zusammenfassung |
| In order to model seismicity during the 1982-1984 unrest at Campi Flegrei caldera (Italy), we
compute static stress changes caused by an inflating source in a layered half-space. Stress
changes are evaluated on optimally oriented planes for shear failure, assuming a regional
deviatoric stress with horizontal extensional axis trending NE-SW. The inflating source is
modelled as inferred by previous studies based on the inversion of geodetic data and having
the same crustal model here assumed. We found that the area affected by the largest Coulomb
stress changes is elliptical and that inverse slip over the source can be discouraged
by the assumed regional stress. These results are in agreement with observations
concerning seismicity developed during the 1982-1984 unrest at Campi Flegrei. We
assume that the temporal evolution of uplift observed by a tide-gauge at Pozzuoli,
normalized to the maximum value, was due mainly to time dependent processes
occurring at the inflating source. We attribute the same normalized time-dependence to
each component of stress change (shear and normal stress changes) averaged in
the region interested by the observed seismicity. We then model seismicity rate
changes associated to these time-dependent stress changes, by following the approach
indicated by Dieterich (1994) on the basis of the rate- and state-dependent rheology of
faults. The seismicity rate as a function of time resulting from the present model is
in general agreement with observations for the period 1982-1984. According to
observations, several peaks of deformation rate history are closely followed by
peaks in seismicity rate. In order to model this effect, a prompt response of the fault
system is required, allowing to constrain the direct effect on friction (aÏ) on the same
faults. |
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