SAR interferometry in post-seismic ground deformation detection related to the 2001 Bhuj earthquake, India

The 2001 Bhuj earthquake, which occurred due to rupturing of a hidden reverse fault, caused large-scale ground deformation. The ground deformations in the Bhuj earthquake-affected region have been analysed using two interferometric synthetic aperture radar (InSAR) data sets. The data sets belong to the years 2003-2004 and 2004-2005, covering an area east of Bhuj falling on near-flat terrain north of Kutch Mainland Fault (KMF). Two interferograms have been generated successfully displaying the interference fringes in the study area, enabling us to draw interesting observational inferences. The 2003-2004 interferogram image exhibits upliftment of about 8 cm (surface motion towards the satellite) around Kunjisar village and also upliftment of 25 and 5 cm in the other two areas north of Kunjisar, whereas the interferogram image belonging to the year 2004-2005 reveals subsidence of about 17 cm (surface motion away from the satellite) in Kunjisar area along with subsidence of about 28 and 5 cm in the two areas north and northwest of Kunjisar, respectively. Hence, between the years 2003 and 2005, two different episodes of upliftment and subsidence have been observed in the study area. The ground upliftment during 2003-2004 probably indicates that the last phase of ground deformation in the earthquake-affected region has been followed by the onset of subsidence during 2004-2005 as the rock volume involved in stress-strain processes began to experience a relaxation phase.