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International cooperation and technology transfer
Mussio, Luigi

Achilli V. 1 ' 2 , Borgstrom S. 2 , Capone M. 2 , Del Gaudio C. 2 , De Martino P. 2 , Klees R. 3 , Ricciardi G.P. 2 , Ricco C. 2 , Sepe V. 2 ,
Usai S. 3 , Vettore A 1
1 Dipartimento Costruzioni e Trasporti - University of Padua (Italy)
2 Osservatorio Vesuviano - Naples (Italy)
3 Delft University of Technology - The Netherlands
Commission VI, Working Group 3
KEY WORDS: Spirit leveling, Tiltmetry, GPS, INSAR
The surveillance of the neapolitan volcanic area is carried out by the Osservatorio Vesuviano also by means of the study
of ground deformations. In the work, the results obtained from the application and comparison of different surveying
techniques in the Phlegrean Volcanic District (Phlegrean Fields and Ischia island) will be presented and discussed. In
particular, the Phlegrean Fields area is marked also by strong vertical ground displacements. Two different spirit leveling
networks are regularly measured in the Phlegrean Volcanic District by several years; from the beginning of the nineties, 4
tiltmetric stations at the Phlegrean Fields were installed, together with a 30 vertices GPS network in 1997. Starting from
December 1996, on the island of Ischia a 20 vertices GPS network was materialized and measured two different times.
In the frame of an international collaboration, some interferograms for the Phlegrean Fields area were obtained: they
were compared with the results of classical surveying techniques, giving a good agreement.
The Phlegrean Volcanic District (Naples - Italy) includes
the volcanic areas of the Phlegrean Fields and the
islands of Ischia and Procida.
The Phlegrean Fields caldera is located in the NE part
of the district and the magmatic system is still active, as
testified by Mt. Nuovo eruption in 1538, by the recent
bradyseismic crises of 1969/72 and 1982/84 and by the
diffuse fumarolic and hydrothermal activity. From the
geological point of view, the caldera is mainly formed by
volcanic rocks and subordinate^ by clastic sea
sediments; from the structural point of view, the
configuration of the phlegrean area is the result of
deformation events related to the regional tectonics and
to the volcano-tectonics. The regional tectonics is the
cause of direct faults with NE-SW and NW-SE direction
and subordinate^ with NS direction.
The magmatic chamber is located at low depth (about
4-5 Km).
Considering that inside the phlegrean caldera and in the
surrounding areas live about two million people, it is
possible to deduce that the volcanic risk of the area is
extremely high.
The island of Ischia is located in the NW sector of the
gulf of Naples and is mainly formed by volcanic rocks,
by landslide deposits of different type and subordinate^
by sea sediments.
Also the structural setting of the island of Ischia has
been determined by deformations induced both by the
regional tectonics and by the volcano-tectonics.
The regional tectonics is the cause of two main fault
systems with NW-SE and NE-SW direction.
At the moment, the presence of a magmatic system still
active and potentially able to give future eruptions is
testified, besides by the last eruptive event occurred in
1302 (the Arso eruption), also by an intense fumarolic
activity, by seismic activity and by vertical ground
2.1 High precision spirit leveling
The altimétrie network of the Phlegrean Fields (fig. 1 ),
considering also the lines in common with the Vesuvian
and the regional networks, is formed by 300
benchmarks distributed on about 120 km of leveling
line, with a mean distance of about 400 m on eleven
Fig. 1 Geodetic surveillance networks of the Phlegrean