Bharath Shekar

bshekar [at] iitb [dot] ac [dot] in
21, Department of Earth Sciences
Phone : +91-22-2576 7296

I completed my PhD in Geophysics from the Center for Wave Phenomena, Colorado School of Mines in November, 2013. I graduated with an Integrated M.Sc in Exploration Geophysics from IIT Kharagpur in 2008. I primarily work on inverse problems connected to seismic wave propagation. My resume in .pdf format.

Prospective students

I am currently looking for students with an aptitude for scientific computing (preferably in Python) for research assistant (one year) and PhD positions.

A few of the prospective PhD themes:

1. Sub-basalt seismic imaging and waveform inversion
2. Ambient noise tomography and inversion
3. Near-surface seismic characterization
4. Physics guided neural networks

Interested students may get in touch by email for more details.

N.B. I do not offer any summer/winter internships and may not be able to reply to emails seeking summer/winter internships.

Google Scholar Page 

All papers are hosted on Researchgate

• Singh, S, G. Mohan,  B. Shekar and S. K. Singh, 2023, Local earthquake tomography of the Cachar fold and thrust belt in lower Assam, Northeast India: Geo-Marine Letters, 43, 21.

• Datta A., B. Shekar and P. L. Kumar, 2023, Acoustic full waveform inversion for 2-D ambient noise source imaging: Geophysical Journal International, 234 (3), 1628–1639.

• Nawal M., B. Shekar and P. Jaiswal, 2023, Integration of sparse and continuous datasets using machine learning for core mineralogy interpretation: The Leading Edge, 42, no.6, 421-432.

• Shekar, B., G. Mohan and S. K. Singh, 2022, Structural information derived from ambient noise tomography over a hydrocarbon producing region in Cachar fold belt, lower Assam, northeast India: Geophysical Prospecting, 71, no. 1, 140-162

• Kumar, N., B. Shekar and S. Singh, 2022, A Nodal Integral Scheme for Acoustic Wavefield Simulation: Pure and Applied Geophysics, 79, 3677-3691

• Vashisth, D., B. Shekar and S. Srivastava,  2022, Joint inversion of Rayleigh wave fundamental and higher order mode phase velocity dispersion curves using multi-objective grey wolf optimization: Geophysical prospecting, 70, no. 3, 479-501

• Kuldeep, B. Shekar, G. Mohan and S. K. Singh, 2022, Assessment of Seismic Vulnerability using the Ambient Noise Recordings in Cachar Fold Belt, Assam: Journal of the Geological Society of India, 98, 795-804

• Kuldeep and B. Shekar, 2021, Full waveform inversion with random shot selection using adaptive gradient descent: Journal of Earth System Science, 130, no. 4, 183

• Shekar, B., and H. Sethi, 2019, Full waveform Inversion for microseismic events using sparsity constraints: Geophysics, 84, no.2, KS1-KS12 

• Shekar, B., and I. Tsvankin, 2014, Kirchhoff modeling for attenuative anisotropic media using Gaussian beams: Geophysics, 79, no.5, WB51-WB61 

• Shekar, B., and I. Tsvankin, 2014, Point-source radiation in attenuative anisotropic media: Geophysics, 79, no.5, WB25-WB34  ( featured in “Geophysics bright spots”, The Leading Edge 33:1162-1162

• Behm, M., and B. Shekar, 2014, Blind deconvolution of multichannel recordings by linearized inversion in the spectral domain: Geophysics, 79, no.2, V33-V45 (featured in “Geophysics bright spots”, The Leading Edge 33:336-336 )

• Shekar, B., and I. Tsvankin, 2012, Anisotropic attenuation analysis of crosshole data generated during hydraulic fracturing: The Leading Edge, 31, no.5, 580-587 

• Shekar, B., and I. Tsvankin, 2011, Estimation of shear-wave interval attenuation from mode-converted data: Geophysics, 76, no.6, D11-D19 

Conference publications:

• Nawal, M., S. Kumar and B. Shekar, LithoBot: An AutoML approach to identify lithofacies, Second International Meeting for Applied Geoscience & Energy, 1885-1889

• Vashisth, D., and B. Shekar,  2019, Inversion of Rayleigh Wave Phase and Group Velocity Dispersion Curves for S-wave velocity by Grey Wolf Optimization: 81st EAGE Conference and Exhibition, EAGE, Expanded Abstracts

• Shekar, B., and D. Nanda, 2018, Seismic Spectral Decomposition with Smoothed Pseudo Wigner-Ville Distribution: 80th EAGE Conference and Exhibition, EAGE, Expanded Abstracts

• Sethi, H., and B. Shekar, 2017, Full waveform Inversion for microseismic events using sparsity constraints: 87th Annual International Meeting, SEG, Expanded Abstracts, 2574-2579

• Shekar, B., and A. Nath, 2015, Gradient computation for simultaneous microseismic event location and velocity inversion by eikonal tomography: 85th Annual International Meeting, SEG, Expanded Abstracts, 2604-2609

• Shekar, B., and I. Tsvankin, 2013, Kirchhoff modeling for attenuative anisotropic media: 83rd Annual International Meeting, SEG, Expanded Abstracts, 3406-3410

• Shekar, B., and I. Tsvankin, 2012, Attenuation analysis for heterogeneous transversely isotropic media: 82nd Annual International Meeting, SEG, Expanded Abstracts, 1-6

• Shekar, B., and I. Tsvankin, 2011, Anisotropic attenuation analysis of a cross-hole data set: 81st Annual International Meeting, SEG, Expanded Abstracts, 474-478

• Shekar, B., and I. Tsvankin, 2010, Estimation of shear-wave interval attenuation from mode-converted data: 80th Annual International Meeting, SEG, Expanded Abstracts, 187-191.

I regularly teach two courses in Seismic Data Processing (GP 418 & GP 517) to M.Sc: Applied Geophysics  students. I also teach an introductory course on seismic methods (GS 701) to M.Tech: Petroleum Geoscience students. I also offer a PhD course on seismic wave propagation (GS 801) every alternate year.  Previously, I have taught Global Geophysics (GP 401) and Geophysical Inverse Theory (GP 506). The topics (non exhaustive) for the courses that I regularly teach:

• Exploration Seismology – I (GP 418): Introduction to seismic acquisition and geometry: types of sources and receivers, digital data, data sorting, reading and writing SEGY data. CMP processing: normal moveout, velocity analysis and stacking. Static corrections: concept of datum and surface consistency, field, residual and refraction statics.  Discrete signals, LTI systems, Convolution & Correlation, Z-transforms. Applications of convolution: simple filters, well to seismic tie. Fourier transforms & identities, sampling theorem. Deconvolution, Wiener filters, applications: spiking deconvolution & prediction error filtering, vibroseis data processing. Coherent noise suppression: multiple suppression by prediction error filtering, radon transforms, SRME; ground roll attenuation with source and receiver arrays, and FK filtering. Random noise attenuation with FX deconvolution. 

• Exploration Seismology – II (GP 517):  Post stack time and depth migration: exploding reflector model, migration by wavefield extrapolation, Kirchhoff migration, migration by diffraction summation, Fresnel zone and seismic resolution. Convolutional model and well to seismic tie. Computation and analysis of seismic attributes. Elastic wave equation, reflection and transmission coefficients, Zeoppritz equations and AVO.  Pre-stack Kirchhoff migration, common image gathers and traveltime tomography. Reverse time migration, least squares and true-amplitude migration. Angle gathers and AVA inversion. 

• Computational Methods in Exploration Seismology (GS 801): Acoustic and elastic wave equations. Finite difference, finite element and pseudo spectral methods of modelling the wave equation. Green’s functions, Representation and Reciprocity theorem. Forward and adjoint wave equations. Lippmann-Schwinger equation and Born approximation. Ray theory: Eikonal and Transport equations. Initial value ray tracing and upwind solutions to the Eikonal equation.   Seismic attenuation: Kramers-Kronig relations, constant Q models, viscoacoustic wave equation. Waveform inversion: frequency and time domain implementations, adjoint state method, optimization algorithms, role of misfit functions. Introduction and applications of Seismic interferometry. Ambient noise tomography and waveform inversion for noise sources and earth structure.

• Seismic Data Processing and Seismic Stratigraphy** (GS 701): Theory and geometry of seismic wave propagation, Seismic wave velocities in rocks, Review of marine and land seismic data acquisition techniques; Fundamentals of time series analysis, auto and cross correlation, convolution, sampling theorem and aliasing, filtering, deconvolution; Data enhancement techniques  Noise reduction, traveltime correction, stacking, wavelet processing, frequency filtering, velocity analysis, amplitude correction, migration techniques, seismic interpretation and attribute analysis.

          ** Syllabus listed only for the first half of the course

Shweta Pandey, PhD candidate.                                                                                                                                                                                                                                                     

Thesis topic: Near surface characterization with active and passive seismic data
Current degree: M.Sc-Tech in Applied Geophysics (2015) from Indian School of Mines, Dhanbad

 Prakash Ranjan, PhD candidate.

Thesis topic: Real-time monitoring of microseismic events.
Current degree: M.Sc in Applied Geophysics (2011) from IIT Bombay

Alumni:

Aparajita Nath, Project Staff (2014-15). Went for a PhD at Delft University of Technology