Bhuj (2001) aur Muzaffarabad (2005) bhukampon ke purv tatha baad ke bhukampon ka tulnatmak addhyayan

Abstract

Bhuj (2001) and Muzaffarabad (2005) earthquakes of same moment magnitude of Mw : 7.6 occured in different techtonic regions i.e., intraplate and interplate regions of Indo-Eurasian plates respectevely. Keeping this in view, their comparative study has been attempted in this paper. A detailed catalogue of earthquakes has been prepared to study seismicity of Kutchh region by including historical and paleoseismic data. Discussion on seismicity of Muzaffarabad (2005) earthquake is based on IMD catalogoue of earthquakes. Difference has been found between Bhuj (2001) and Muzaffarabad (2005) earthquakes based on their foreshocks, magnitudes of aftershocks and their decay, b-value and their spectra. Though no relation between magnitudes of aftershocks and stress drop could be found but mostly the corner frequency and magnitude are inversely related. Difference in both these large earthquakes (M>=7.6) occurring in different tectonic plate set up is clearly evident from their stress drop. Seismic gap is noticed prior to main event of Muzaffarabad earthquake; which is similar to other Himalayan earthquakes of that region like Uttarkashi (1991) and Chamoli (1999). From the point of view earthquake prediction, the results based on satellite thermal anamolies, ionosphere, electromagnetic and sodar observations reported for these earthquakes are considered to be of limited value due to the large influence of atmospheric parameters. Though approximate displacement measured through GPS is useful for calculating the plate motion but their results to derive large vertical displacement is questionable in any case of Bhuj earthquake due to use of standard radio atmosphere. The errors in such results can be reduced by adopting radio atmosphere for the Indian region. Through a review of methodologies to predict the strong ground motion in the near field, it is evident that further research is called for.