This ground subsidence over the Nobi Plain became well known following the Ise-wan Typhoon (Typhoon Vera) in autumn 1959. In its Annual Report in 2000, the Land Subsidence Survey Committee of the Three Prefectures in Tokai Region reported that, after the 1959 typhoon, a gradual expansion of the subsidence area peaking in 1973�C1974 was observed, followed by a slowing trend in subsidence activity since then, more likely because of such factors as the strengthening of regulations concerning groundwater pumping [6]. We have to note here that very few researches have been performed on this subject so far, notwithstanding the remarkable ground subsidence still observed to occur in some areas of this Plain, even nowadays, or the rising grounds found in many other parts.

These changes in ground level conditions are likely to imperil the foundations of life-sustaining infrastructures in this area, including damages to built up structures, especially in the case of tsunamis or sea level increase due to the global warming. All these facts are a great source of concern for residents in the region [7].Ground leveling, the traditional method for observing ground subsidence, makes it possible to directly measure ground subsidence with quite high precision. However, this method remains crippled with many issues, among which the shortage in manpower, the volume of labor and the cost required for performing the measurements, the cost for the maintenance and management of observational points, as well as the inability to get observation information for those areas not included in the leveling routes and ground points network [8,9].

The analysis on ground changes by InSAR can be expected as in recent Cilengitide years, interferometric synthetic aperture radar (InSAR) technology [10�C12] has been more and more in use to estimate with high precision the spatial distribution of changes in the Earth’s crust surface height and the amount of such changes at each specific location [13�C19]. This new approach can be considered as a complementary method to by traditional standard measurements for monitoring ground subsidence. More specifically, ground level subsidence reported in relationship with the overexploitation of ground waters has been analyzed using InSAR techniques in many parts of the World. This is the case of Lisbon in Portugal [20], the Pingtung Plain [11] and the Chousui River Alluvial Fan [21] in Taiwan, the Campania Region [22] and Bologna [23] in Italy, as well as Kolkata City in India [24]. It is expected the InSAR techniques, as well as its more recent variants such as the PSInSAR [25], will become powerful complementary, or even substitute, methods to traditional ground subsidence observation using leveling and other methodologies used so far.