Abstract
A series of 2-D conductive/convective numerical models show a rather
limited range of possible magma chamber configurations that predict
the present thermal regime at Campi Flegrei. These models are calculated
by HEAT, which allows continuous adjustment of heterogeneous rock
properties, magma injection/replenishment, and convective regimes.
The basic test of each model is how well it reproduces the measured
thermal gradients in boreholes at Licola, San Vito, and Mofete reported
by AGIP in 1987. The initial and boundary conditions for each model
consists of a general crustal structure determined by geology and
geophysics and major magmatic events: (1) the 37 ka Campanian Ignimbrite;
(2) smaller volume 37-16 ka eruptions; (3) the 12 ka Neapolitan Yellow
Tuff; (4) recent magmatism (e.g., Minopoli at \~10 ka and Monte
Nuovo in 1538 AD). While magma chamber depth is well constrained,
magma chamber diameter, shape, volume, and peripheral convective
regimes are poorly known. Magma chamber volumes between 200 and 2000
km3 have been investigated with cylindrical, conical (funnel-shaped),
and spheroidal shapes. For all reasonable models, a convective zone,
developed above the magma chambers after caldera collapse, is necessary
to achieve the high gradients seen today. These models should help
us understand recent bradyseismic events and future unrest.
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