institution of two new GPS vertices in Forio d’lschia, 
measured for the first time during 1998. 
Achilli, V., Artese, G., Borgstrom, S., Capone, M., Del 
Gaudio, C., Gandolfi, S., Ricciardi, G.P., Ricco, C., 
Salemi, G., Sepe, V., Vettore, A., 1998. Metodologie 
integrate di rilievo GPS nell’area vulcanica napoletana. 
Proceedings of the 2° National Conference of the ASITA, 
Voi.1:105-111. 
Barberi, F., Corrado, G., Innocenti, F., Luongo, G., 1984. 
Phlegrean Fields 1982-1984: brief chronicle of a volcano 
emergency in a densely populated area. Bull. Volcanol., 
47(2): 175-185. 
Fig. 13 Vertical displacements (5/90-5/97) along the 
Borbonica line (NW side) in the island of Ischia 
From the comparison between the GPS measurements 
carried out in 1997 and 1998, eventual ground 
deformations acting in the island during this period, are 
inside the error interval which is typical of the GPS 
technique. 
In general, from the comparison among the three different 
GPS techniques used during 1997 measurements, it is 
possible to point out that the results obtained are 
comparable, depending on the reduced dimensions of the 
island: this implies that the use of the RTK technique can 
be suggested, considering its favourable operating and 
processing features, as a real time monitoring system 
during eventual emergency cases. 
5. REFERENCES 
Achilli, V., Al Bayari, O., Artese, G., Borgstrom, S., Coppa, 
U., Del Gaudio, C., Gandolfi, S., Nave, R., Ricco, C., 
Sepe, V., Targa, G., Vettore, A, Macchiavelli, N., 
Siniscalchi, V., Tini, M.A., 1997. Control GPS network in 
the volcanic area of Ischia island (Italy) and RTK 
surveying application. Reports on Geodesy, (Janusz 
Sledzinski editor): 55-65. 
Achilli, V., Artese, G., Borgstrom, S., Capone, M., Coppa, 
U. , Del Gaudio, C., Macchiavelli, N.. Nave, R., Ricco, C., 
Sepe, V., Siniscalchi, V., Vettore, A, 1997. Ischia Project: 
The GPS Network. Acta Vulcanologica. In press. 
Achilli, V., A Bayari, O., Artese, G., Borgstrom, S., 
Capone, M., Coppa, U., Del Gaudio, C., Gandolfi, S., 
Macchiavelli, N.. Ricco, C., Sepe, V., Vettore, A, 1998. 
GPS measurements in the neapolitan volcanic area. 
Proceedings of the 23° General Assembly of the 
European Geophysical Society. In press. 
Achilli, V., A Bayari, O., Artese, G., Borgstrom, S., 
Capone, M., Coppa, U., Del Gaudio, C., Galvani, A, 
Gandolfi, S., Macchiavelli, N., Nave, R., Ricco, C., Sepe, 
V. , Siniscalchi, V., Targa, G., Tini, M.A, Vettore, A, 1997. 
Rete GPS nell'area vulcanica dell'isola di Ischia: confronto 
tra misure statica, rapido-statica ed RTK Proceedings of 
the 16° Congress of the Gruppo Nazionale di Geofisica 
della Terra Solida. In press.