8. SIGNIFICANT CONTRIBUTION IN RESEARCH & TEACHING
(During past five years)
I am involved in the development of an efficient finite-difference method for the simulation of (a) seismic wave propagation, (b) study of local site effects both basin and topography and (c) site-specific strong ground motion prediction. Simulation of ground motion characteristics based on wave propagation is the today’s need for cost effective Earthquake Engineering, seismic hazard prediction, risk evaluation and seismic microzonation.
Currently, I have developed 2D and 3D 4th order accuracy finite-difference algorithms based on staggered grid approximation of viscoelastic wave equations for implementation of frequency dependent damping in the time-domain simulations (AG, 2013; 15WCEE, 2012). These algorithms have the facilities of source implementation based on earthquake dynamics and use of improved vacuum and stress imaging techniques as free surface boundary conditions, which facilitates the study of site-city interaction and surface topography on ground motion characteristics.
I have also developed a new free surface boundary condition known as VGR-stress imaging technique, better than the well known stress imaging technique in terms of avoiding the soil thickness discrepancy and numerical dispersion of Rayleigh waves (PAGEOPH, 2008).
A procedure has been developed for carrying out the seismic microzonation of a city based on assessment of local site effects using seismic wave propagation and the same is applied for the seismic microzonation of Kolkata city, a challenging job due to soft, layered and very thick soil deposit (AG, 2013; NZ, 2012).
The generation process of Rayleigh wave in a homogeneous medium, particularly the dependency of frequency of Rayleigh wave on focal depth is also studied.
I have developed a new research area in India namely study of LOCAL SITE EFFECTS on ground motion characteristics based on seismic wave propagation and have published various papers on different aspects of local site effects in various SCI-journals of repute.
Recently, I have inferred and documented the effects of basin on surface wave amplification and their complex mode transformation at the basin-edge (PAGEOPH, 2012; 2010).
Effects of 2D and 3D basin-edge geometry, angle of incidence of body waves at the edge, soil velocity, thickness and soil layering on the edge induced surface waves have been studied in detail (JET, 2012; AG, 2009; JESS, 2008, 03; JEE, 2006; PAGEOPH, 2005).
I have studied in detail the effects of both the surface and sub-surface basement topography on ground motion characteristics (AG, 2013; Geofizika, 2013; 15WCEE; JEE, 2003; PAGEOPH, 2003).
The role of underground ridges (UGR) in surface wave generation considering existence of various UGRs in the Ganga-Yamuna basin (GJI, 2006).
During the past five years, I have published 14 papers in refereed SCI international/national journals.
I have supervisedOne Ph. D. Thesis and Five M.Tech. thesis.
I have developed three PG course ‘Principles of seismology (EQ:598)’; ‘Seismological modelling and simulation (EQ:531)’ & ‘Advanced seismic microzonation (EQ:534)’.
I have taught four PG courses (EQ:503-Engineering Seismology; EQ:531-Seismological modelling and simulation; EQ:534-Advanced seismic microzonation & EQ:522-Seismic Microzonation) and two UG course (IEQ:02- Engineering Seismology and Seismotectonics & IEQ:03-Understanding Earthquake Hazards and Disaster) during the past five years.