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Avviso di seminario - Dott. Luca De Siena
Mercoledì 06 Luglio 2016 ore 14:30
Aula ex biblioteca - Dipartimento di Fisica e Geologia
Dott. Luca De Siena
Time-space seismic-energy evolution of a supervolcanic unrest: unraveling where it came from and what will produce the next
Time-dependent seismological imaging is probably the most important tool to monitor
changes in volcanological structures. When using unrest data at supercalderas, however,
these techniques are generally considered difficult to upscale to eruptive events and
insufficient for reliable interpretations of volcano dynamics. Here, we combine recent
developments in seismic attenuation and rupture imaging with geochemical,
geomorphological, and rock-physics interpretational tools and resolve in time and space
the deepest paths of magmatic fluids and gases producing Campi Flegrei largest monitored
unrest (1982-1984). This is the first 4D seismological evidence of how the volcano built up
and released stress via day-long supercritical fluid injections, whose deeper SE-to-NW
striking source is located at the offshore boundary between subsiding and resurgent
portions of the caldera. The consequent repeated degassing under the caprock makes the
volcano more prone to deform until the peak of the seismic crisis, corresponding to an
intense earthquake followed by aseismic slip. The drastic change in permeability activates
deep fluid circulation to local geothermal areas via known structural paths and enhances
today-present accumulation in the low-gravity subsiding offshore portion of the caldera.
The end-of-crisis stress-release and subsidence mechanisms are similar to those dating
back to the fifth century and preceding historical volcanic eruptions. The results clarify the
mechanisms behind the frequent unrests at the volcano and hold promise of forecasting
future deep paths of eruptive materials.
Dott. Daniele Morgavi

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