SAR interferometry and field data of Randazzo landslide (Eastern Sicily, Italy)

With the aim of improving our understanding of the development and potentia l instability of the Randazzo landslide which occurred in the months of Mar ch and April, 1996, inclinometric, piezometric and topographical data were collected and compared with the results of differential interferometric ela boration (DIFSAR), up till the end of 1998 using the data of ERS1 and ERS2 satellites, that detected displacements of 1cm a day. The elaborations enable us to individuate the morphology of the earth mass in movement, and to consider displacements detected in a short time-interva l at the end of paroxysmal stage (3-4 April). They show that after the even t displacements stopped, or were of such low velocity so as to be not detec table by this technology, apart from in limited areas. These results seem t o be in accord with those obtained from inclinometric measurements, which s how displacements all within the range of instrumental error. Recently, a DIFSAR elaboration over a period of seventy days (25 August- 4 November 1998) has revealed a clear image of the entire landslide body. Com ing at the end of a particularly dry period and being associated with a dis crete lowering of the water table the variations could be the combined resu lt of a small contraction of the flowed masses (not detected by inclinometr ic measurements) on account of drought and/or a strong variation in the die lectric constant. In either cases the detected variations are caused by the strong difference in physical properties of the flowed masses from the sur rounding areas. (C) 2000 Elsevier Science Ltd. All rights reserved.