Spostamenti rilevati alle stazioni GPS della rete IGM95 poste nell'area dell'Appennino umbro-marchigiano dopo gli eventi sismici del settembre-ottobre 1997

In this paper we present the GPS data collected at 18 stations of the IGM95 GPS network, in the Colfiorito and Sellano areas. The data show ground deformations due to the largest earthquakes of the umbria-marche seismic sequence of September-October, 1997. The first two events, occurred on September 26, M w = 5.7 and M w = 6.0, produced planoaltimetric displacements up to 25 cm in the Colfiorito area. The October 14, 1997 earthquake, occurred near Sellano village and produced visible ground deformations that were not revealed at the GPS monuments due to the unfavorable GPS IGM95 network configuration in this area. We present and discuss the whole geodetic data set collected in the area, useful to update the 3-D coordinates of the IGM95 GPS monuments, for scientific and civil applications.