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| Titel |
First in-situ rock parameters measurements at Campi Flegrei caldera from CFDDP experiment: implications for hazard and eruption forecast. |
| VerfasserIn |
Stefano Carlino, Anna Tramelli, Monica Piochi, Renato Somma, Claudia Troise, Giuseppe De Natale |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250082365
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| Zusammenfassung |
| Campi Flegrei Deep Drilling Project (CFDDP) started on July 2012, in the framework of
International Continental Scientific Drilling Program (ICDP), aimed to understand the
physics of volcanic processes at this area. The first drilling phase of CFDDP involved a pilot
well 500 m deep, located within the easternmost border of the caldera, hosting
the densely populated western part of the city of Naples (Southern Italy). Such a
first drilling phase has been carried out in about 2 months, ending in December
2012.
At the bottom of the pilot well, a leak of test (LOT), specifically adapted to the solution of
the main open scientific problems, was performed. The pressure vs time data have been used
to evaluate, for the first time at Campi Flegrei, the in situ permeability of the rock formations
and the stress level of the area. These parameters are crucial for the validation of physical
models of Campi Flegrei caldera dynamics. Interpreting the large uplift of the area cumulated
in the last thousands years is in fact a critical issue to understand the amount of magma
accumulated in the shallow layers, which can be mobilized in a future eruption.
A simple, purely magmatic model would imply, depending on the model details,
the accumulation of 1 to 10 km3 of new magma in shallow reservoirs. It would
correspond to a huge eruption which would require evacuation of several millions
people. An alternative hypothesis, much discussed in the recent literature, is that
a large part of uplift depends from the injection of deep fluids into the shallow
geothermal system. Such hypothesis is much less dramatic in terms of risk, but
the real feasibility of such kind of model heavily relies on the values of average
permeability at depth, which is an unknown parameter. The measured in-situ values,
from 10-14to about 10-15m2, are consistent with those required, by theoretical
models, to reproduce the observed uplift in terms of perturbations of the geothermal
system, thus experimentally validating, for the first time, a model alternative to a
purely magmatic one. Another important measurement performed during the LOT
experiment is the value of rock strength, and the minimum tectonic stress loading.
Such parameters improve a lot our ability to model physical process at this area,
giving a fundamental contribution also to volcanic risk assessment and mitigation. |
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