## Details of ES3105 (Autumn 2019)

Level: 3 |
Type: Theory |
Credits: 4.0 |

Course Code | Course Name | Instructor(s) |
---|---|---|

ES3105 |
Seismology |
Kajaljyoti Borah |

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

Syllabus |
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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? |

Prerequisite |
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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. |

References |
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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. | Programme | Semester No | Course 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 |