Earth,Atmospheric, Ocean & Planetary Sciences Paper 2 Geophysics
(i) Geophysical Fields: Concept of fields; scalar, vector and tensor; conservation laws; mass, momentum, energy and charge; constitutive relations: and dynamical equations: elastic, viscous, electro-magnetic, and thermal; Laws of thermodynamics and entropy; Partial differential equations of physics: wave, diffusion, potential and Schrodinger; analytical (Green’s functions and integral transforms) and numerical (Spectral, finite difference and finite element) methods for solving initial value and boundary value problems of geophysics.
Linear instability theory and onset of convection; Benard Cells; Elements of nonlinear instability in fluids; Theory of Attractors; phase space, critical points, limit cycles and bifurcation of nonlinear systems.
(ii) Signal Processing: Continuous and discrete signals; Fourier analysis; linear time-invariant systems with deterministic and random inputs; bandlimited signals and sampling theorem; Z- transform, discrete and Fast Fourier transforms; filters: discrete and continuous, recursive and non-recursive, optimal, inverse filters, deconvolution. Estimation of signal parameters, system identification. Hypothesis testing.
(iii) Solid Earth: Gravity and figure of the Earth: spheroid and geoid; mass inhomogenetics and associated gravity anomalies; geoidal undulations and deflection of the vertical; isostasy: local and regional compensation mechanisms. Seismology: causes and space distribution of earthquakes; theory of seismic waves; (body and surface waves), free oscillations, application for estimating earth structure and earthquake source parameters; earthquake hazard assessment. Geomagnetism; main field, its secular variation and reversals; remnant magnetization, paleomagnetism and lithospheric movements; geodynamo theory and hydromagnetic waves; magnetosphere and geomagnetic storms. Electrical structure of the earth; geomagnetic and magnetotelluric depth sounding. Plate tectonics theory: kinematics, dynamics and evolution of plates; types of boundaries, processes and corresponding geophysical and geological signatures. Heat flow: thermal and mechanical structure of continental and oceanic lithosphere; role of fluids in crustal processes; mantle convection. Mineral physics; constraints on earth structure from seismological and petrological investigations.
(iv) Geophysical Exploration: Basic principles: various methods, their distincitve features, scope, limitations and prospects of conjuctive use. Geophysical exploration from the air, on the ground, in bore holes, across drill holes, in underground mines and in the oceans.
Instruments used: theory, behaviour and precision of spring-mass systems, magnetometers (suspended magnet type, nuclear precession, nuclear resonance, flux gate and superconducting), Gravimeters (land, shipborne, spaceborne and borehole), wide band seismograph and geophone systems. Electrical systems, (resistivity,
Principles of measuring complex signals; measurements in time and frequency domain. Pseudorandom sources for electrical and seismic exploration.
Signal Analysis: Gravity (free air, Bouguer, terrain, drift and Eotvos corrections) and magnetic (diurnal) and latitude (corrections) data reduction; regional and residual separation; derivatives, continuation and reduction to pole of potential field data. Electrical/EM data processing, Seismic (velocity analysis, signal enhancement, deconvolution, migration and time to depth conversion), Shear wave, VSP, 2-D/3D multifold and marine data processing. Numerical experiments for computer aided design of high-resolution field measurements; sensitivity analysis of various control parameters for maximum information/uncertainty ratio.
