Quantification of intensity of landscape changes using remote sensing and GIS with special reference to the Bhuj earthquake (26th January, 2001, M = 7.9)

Abstract

Change detection is used to detect changes after the Bhuj earthquake of January 26, 2001 and quantify the intensity of changes using remote sensing and GIS techniques. Changes are generally studied for their locations and spatial distribution, band sensitivity, aerial extent (quantity of changes), nature (permanent change, seasonal/cyclic change) and processes are inferred that may have led to the changes. The present research is an attempt to quantify the intensity of changes using remote sensing and GIS techniques. It may be possible to just visually detect changes in landscape, but to detect the variations in intensity of changes, techniques of image processing need to be employed. In the present study, one of the techniques of change detection, namely ‘temporal band differencing,’ is used to detect changes in landscape and their intensity after the Bhuj earthquake (26th January 2001, magnitude = 7.9 on Richter scale). In this method of change detection, temporal difference between two images is computed by subtracting time 2 image values from time 1 image values (brightness values) of corresponding pixels. Output image contains absolute differences in brightness values of corresponding pixels. This research work attempts to study the change detection technique in which bandwise change detection and areawise change detection is carried out. All the changes are then correlated with the geology and tectonics of the area around Bhuj and epicenter of the Bhuj earthquake.