Paleoseismic analysis of clastic injection dikes within the prehistoric liquefaction fields of Kashmir Karewas

Abstract

Clastic injection dikes were identified within the prehistoric liquefaction fields of Kashmir Karewas, India. Clastic injection dikes are the geological evidence of the past earthquakes formed by seismic liquefaction of susceptible Karewa sediments. The study of clastic injection dikes proves vital paleoseismic tools for understanding prehistoric seismicity. Moderate to strong earthquakes often trigger soil liquefaction that can cause more destruction than the earthquake itself. This study will be helpful in answering: where was the possible seismic source? What were the magnitude, intensity, and PGA of the prehistoric earthquakes? What were the energy values of past earthquakes that were expended to generate observed clastic injection dikes? Empirical relationships were used to estimate paleoseismicity and site-specific seismic liquefaction hazard. The seismic parameters of past earthquakes were obtained using width, height, and regional pattern of observed clastic injection dikes. Paleomagnitudes obtained in this study were computed as a function of paleoepicentral distance,\({W}_{cd}\) and \({h}_{cd}\) values of the clastic injection dikes. \({M}_{S}\) values were ranging from 5.0 to 7.7, and their equivalent \({M}_{W}\) values were ranging from 5.4 to 7.7. The \({I}_{L}\) values computed as a function of \({W}_{cd}\) and \({h}_{cd}\) values of clastic injection dikes were ranging from 6.06 to 13.97. PGA values computed as a function of \({I}_{L}\) values were ranging from 0.07 to 3.75 g. Tremendous amount of \({E}_{o}\) values in joules were expended to generate the observed clastic injection dikes corresponding to \({M}_{s}\) and their equivalent \({M}_{w}\) values. The incorporation of obtained \({E}_{o}\) values in mass-energy equivalence relationship suggests that there is a small amount of Earth’s mass loss during an earthquake. The findings of this study suggest that Kashmir Valley is seismically active region and is giving credible answers to paleoseismic problems. The results of this study provide data set to engineers, urban planners, and policy makers to design earthquake-resistant infrastructure to withstand against great earthquakes in the future.