Temporal change in the structural fabric during pre- and post-26 January 2001 Bhuj earthquake,using remote sensing data

The Bhuj region, Kutch, India, is included in the highly seismic zonation map of India. The Kutch is a rift basin and so far has experienced three major earthquakes that are due to reverse fault mechanism, which in turn have been ascribed to compressive stresses. Origin of these stresses is considered to be due to north–south convergence of the Indian Plate with the Tibetan plate, and this has placed the entire Indian Plate under the compressive stress regime. Analysis of the stress pattern in the Bhuj region, therefore, has been carried out by extracting lineaments with the help of remote sensing data for the pre- and post-earthquake periods of 26 January 2001 earthquake. For this purpose, the area has been segmented into four sectors. The lineament frequency and the percent frequency from each sector and also for the whole area have been worked out. Resolution of stress on the principle of triaxial ellipsoid has been worked out for each sector and also for the whole area. There results a temporal change in the stress pattern in each sector and also for the whole area. However, the direction of horizontal maximum compressive stress for the whole area appears to be in N 10°E in the pre-earthquake period that has changed to N 10°W in the post-earthquake period. Thus, temporal change in the horizontal maximum compressive stress direction as N 23°E, inferred by Gowd et al. (J Geophy Res 97:11879–11888, 1992) to N 10°E prior to and N 10°W in the post-earthquake period, as inferred from lineament analysis and near parallelism of the lineament maxima with that of the North Kathiawar Fault and the Chambal Jamnagar Lineament along with the longer axis of the isoseismals of the Bhuj 2001 earthquake indicates a modification in the structural fabric of the region as well as a possibility of development of a major plane of weakness.