Mrinal Sen's Research Interests
I am primarily interested in developing techniques for seismogram synthesis and imaging, and estimation of rock properties from geophysical data. During my graduate studies I worked on asymptotic methods for seismogram synthesis. You can essentially choose one of the two methods for seismogram synthesis: Exact (or more exact) methods such as the reflectivity methods, which are limited to the type of earth model you can use or Asymptotic methods (such as Ray theory and its variants) where you can use fairly realistic earth models. Of course, you can use finite differences to compute seismograms for fairly complex geologic models but they are slow. Over the last decade, the speed of computers has increased by several orders of magnitude - 3D FD seismograms will probably be used routinely in near future. As computers get faster, we find problems to work on, that need even faster machines. There is no scarcity of such problems in Geophysics. I enjoy developing mathematical and numerical tricks that help make computation faster.
Seismic Migration or Imaging is an art - they are based on wave propagation models. One with a good background in theory can contribute well in this field. Much of the ideas are intuitive - they work amazingly well. The potential of the plane wave methods for imaging has not been explored well. For example it is trivial to extend plane wave theory to include the effects of anisotropy and multi-component data. Much of my current research is focussed on this aspect.
Geophysical inverse problems are an active area of research. Since joining UTIG, I worked on several geophysical parameter estimation problems. We were able to demonstrate that global optimization methods such as simulated annealing (SA) and genetic algorithm (GA) can be used effectively to several geophysical applications such as the seismic waveform inversion problem. I also showed how one could apply Gibbs' sampling and Metropolis rule to characterize uncertainties and the posterior probability density function (PPD) in model space. We are actively pursuing this area of research with application to seismic reflection data from gas hydrates, global seismology, seismic tomography, and anisotropic parameter estimation.
I occasionally develop parallel algorithms for seismic processing, and model earthquake seismograms for large scale earth structures. Jay Pulliam and I are studying seismograms from deep focus earthquakes to constrain anisotrpoic structures of D".
Geophysics is a lot of fun. It is an exciting field to be in - it is truly interdisciplinary. We borrow ideas and techniques developed in Physics, Math, Statistics, Computer Science, Electrical Engg and Biology - to name a few, and apply them to several geophysical problems. Of course the main objective is to solve geologic problems. I would consider it a waste of time to develop a technique that does not work on real data.
Selected Pyublications
Kumar, D., M. K. Sen,
and R. Fergusson, 2004, Travel time and computation and pre-stack depth
migration in tilted TI media, Geophysics, 69(11), 37-44
Sen. M. K., and A. Mukherjee, 2003, t-p analysis in transversely isotropic media, Geophysical J. International, 154, 647-658.
Sen. M. K., and I. G. Roy, 2003, Computation of differntial seismograms and iteration adaptive regularization in pre-stack seismic waveform inversion, Geophysics, 68 (6), 2026-2039
Sen, M.K., P.L. Stoffa, R. Seifoullaev, and J. T. Fokkema, 2003, Airborne GPR for the detection of underground facilities, Subsurface Sensing Technologies and Applications, 4(1), 41-60
Sen, M. K., 2001, Prestack inversion of plane wave seismograms: Isotropy to transverse Isotropy, special volume on “Recent advances in Exploration Geohysics”, RECODER, The Canadian Society of Exploration Geophysicists, 85-96.
Sen, M. K., F. Liu, P. L. Stoffa, and J. T. Fokkema, 1998, A unified treatment of free surface multiple attenuation methods, Journal of Seismic Exploration, 7, 129-143.
Sen, M. K., and P. L. Stoffa, 1996, Bayesian inference, Gibbs' sampler and uncertainty estimation in geophysical inversion, Geophysical Prospecting, 313-350.
Sen, M. K., and P. L. Stoffa, 1992,
Rapid sampling of model space using genetic algorithms: examples from seismic
waveform inversion, Geophysical J. International, 108, 281-292.
Sen, M. K., and L. N. Frazer, 1991, Multifold phase space path integral synthetic seismograms, Geophysical J. International, 104, 479-487.
BOOK
Sen, M. K., and P. L. Stoffa, 1995, Global Optimization Methods in Geophysical Inversion, Elsevier Science Publishing Company, The Netherlands.
