Details of ES3105 (Autumn 2019)

Level: 3 Type: Theory Credits: 4.0

Course CodeCourse NameInstructor(s)
ES3105 Seismology Kajaljyoti Borah

Study of earthquake source, excitation of seismic waves and its
propagation through the Earth

Concept of stress and strain in 3-D: stress and strain tensors, Eigen value problem: computing the principal axes of stress and strain, the linear stress?strain relationship and elastic tensor, seismic body wave velocities in terms of Lame parameters. The seismic wave equation and solutions: The momentum equation, the seismic wave equation, solutions to the wave equation, polarizations of P- and S-waves. Seismic Ray theory: The eikonal equation, travel times, Snells law, ray paths for laterally homogeneous models, ray tracing through velocity gradients, travel time curves and delay times, reduced velocity, the ?(p) function, low-velocity zones, spherical-Earth ray tracing, the Earth-flattening transformation, ray nomenclature, crustal phases, whole Earth phases, global body-wave observations. Ray theory: Amplitude and phase: Energy in seismic waves, geometrical spreading in 1-D velocity models, reflection and transmission coefficients, SH-wave reflection and transmission coefficients, vertical incidence coefficients, energy-normalized coefficients, dependence on ray angle, turning points and Hilbert transforms, matrix methods for modeling plane waves, attenuation, Earths attenuation, observing Q, Seismic attenuation and global politics. Reflection seismology: Velocity analysis, Receiver functions, Kirchhoff theory and migration, statics corrections, Huygens principle, diffraction hyperbolas , migration methods, zero-offset sections, common midpoint stacking , sources and deconvolution, migration. Surface waves and normal modes: Love waves, Solution for a single layer, Rayleigh waves, dispersion, global surface waves, observing surface waves, normal modes. Earthquakes and source theory: Non-double-couple sources, Greens functions and the moment tensor, Earthquake faults, Radiation patterns and beach balls, Example: Plotting a focal mechanism, far-field pulse shapes, directivity, source spectra, Empirical Greens functions, stress drop, self-similar earthquake scaling, radiated seismic energy, earthquake energy partitioning, earthquake magnitude, the b-value, the intensity scale, finite slip modeling, the heat flow paradox. Earthquake prediction: The earthquake cycle, earthquake triggering, searching for precursors, are earthquakes unpredictable?

NOTE: This course is a PRE REQUISITE for the Seismology Laboratory course of spring

For this course, the pre requisites are all DES courses of first and second years.

1. Introduction to Seismology, 2nd Ed., by Peter M. Shearer, 2009, Cambridge University Press.
2. An Introduction to Seismology, Earthquakes, and Earth Structure by Seth Stein, Michael Wysession, January 1991, Wiley-Blackwell.

Course Credit Options

Sl. No.ProgrammeSemester NoCourse Choice
1 IP 1 Elective
2 IP 3 Not Allowed
3 IP 5 Not Allowed
4 MR 1 Not Allowed
5 MR 3 Not Allowed
6 MS 5 Core
7 RS 1 Elective
8 RS 2 Elective