Modeling of Strong-Motion Data in Northeastern India: Q, Stress Drop, and Site Amplification

Abstract

Abstract In this article point source seismological model is used to model the available strong-motion accelerograms in northeastern India. Key seismic parameters such as Quality factor ( Q -value), kappa factor ( κ 0 ), site amplification, and stress drop are derived from the strong-motion data. A total of 111 three-component records coming from seven earthquakes with magnitudes ranging from M w 5.2 to 7.2 are used in obtaining the source and path parameters. The Q -value of the Indo–Burma tectonic domain, which is a subduction zone, is obtained as 431 f 0.7 . For the Bengal basin–Shillong plateau region the Quality factor is estimated as 224 f 0.93 . The kappa factors for vertical and horizontal components are obtained as 0.013 and 0.033 for soft rock type sites. For firm ground sites κ 0 is estimated as 0.025 for vertical and 0.041 for horizontal components, respectively. The site amplification functions for soft rock and firm ground conditions are found from the horizontal-to-vertical ratio. The obtained stress drops of the seven events lie between 128 and 282 bars. The source parameters obtained in this study provide a useful framework for working out ground-motion relations in northeastern India.