Publication Date:
2017-04-04
Description:
The last eruptive event at Mount Vesuvius occurred in 1944 A.D., ending a cycle
of continuous eruptive activity started with the sub-Plinian event of 1631 A.D. The aim of
this research is (1) to model the thermal evolution of the volcanic system from
1631 A.D. up to the present and (2) to investigate the possible process leading the volcano
to the current state of quiescence. A finite element software is employed to solve the
time-dependent energy equation and obtain the thermal field in the volcanic edifice and
the surrounding medium. Volcanological, petrological, and geophysical constraints are
used to define the crustal structure beneath the volcanic edifice, the magma supply system
active since 1631 A.D., and the physico-chemical conditions of magma. Thermodynamic
properties of magma and wall rocks have been evaluated from well-established
thermo-chemical compilations and data from the literature. It is shown that heat transfer
due to magma degassing is required in addition to the heat conduction in order to obtain
transient depth-temperature fields consistent with geochemical observations, high
crustal magnetization, and rigid behavior of the shallow crust as indicated by geophysical
data. Surface data of carbon dioxide soil flux coming out from the Mount Vesuvius crater
are taken to constrain such an additional heat flux. The agreement between modeled
and measured temperatures at the crater since 1944 A.D. proves the consistency of the
model. It is concluded that the present state of quiescence of Mount Vesuvius is
mostly a consequence of the absence of magma supply from the deep reservoir into the
shallower system. This allows the cooling of residual magma left within the volcanic
conduit and the transition from continuous eruptive activity to the condition of conduit
obstruction. In this scenario, the hydrothermal system may have developed subsequent to
the cooling of the magma within the conduit. Our findings are a direct consequence of the
high concentration of CO2 in the most mafic Vesuvian magmas: The low solubility of
CO2, with respect to H2O, enables a high mass flux of carbon dioxide through the volcanic
edifice. The results of this study are relevant for hazard assessment at Vesuvius and
indicate directions for further investigation, such as the role of the hydrothermal system on
the thermal energy budget of the volcanic system and its relationships with fluids
released by crustal structures likely to host the magmatic reservoir. In general, the role of
the high concentration of carbon dioxide in magmas should be more questioned and
investigated when studying the behavior of volcanic systems, particularly in south Italy
volcanoes.
Description:
Published
Description:
B03202
Description:
3.6. Fisica del vulcanismo
Description:
JCR Journal
Description:
reserved
Keywords:
the thermal state
;
Mount Vesuvius from 1631
;
CO2 degassing
;
1944 A.D. eruption
;
04. Solid Earth::04.07. Tectonophysics::04.07.03. Heat generation and transport
;
04. Solid Earth::04.08. Volcanology::04.08.01. Gases
;
04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
;
04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
Permalink
