COURSE OBJECTIVES:
Introduction to the physics of generation and propagation of body and surface elastic waves, and study of their basic properties in simple Earth models.
COURSE CONTENT
1. Basic theory of elasticity (repetitorium),
2-3. Navier and wave equations and their
solutions: Helmholtz theorem, elastic potentials,
4. Fourier principle of superposition. Snell's law, ray parameter. P, SV, SH waves.
5-6. Reflection on the free surface: conversion of phases, coefficients of reflection and conversion.
7. Inhomogeneous waves.
8-9. Rayleigh waves in half space, eigenfunctions.
10-12. Love waves in a layer over half-space, period equation, dispersion, modes.
12-13. Phase and group velocity.
LEARNING OUTCOMES
After completing the course students can:
- Define elastic wave types and their properties.
- Apply the Helmholtz theorem in solving the Navier equation.
- Distinguish between three types of motion (P, SV, SH), and define them.
- Distinguish between homogeneous and inhomogeneous waves, and define them.
- Define boundary conditions end derive reflection and conversion coefficients for P- and SV-waves at the free surface.
- Define boundary conditions end derive reflection and refraction coefficients for SH-waves at the boundary between two media.
- Define boundary conditions and derive period equations for surface waves in the simplest Earth models; discuss the period equation for Love waves and argue for the existence of modes and dispersion.
- Analyse and compute eigenfunctions for Rayleigh waves in the homogeneous half-space.
- Describe the oscillation of particles on the free surface during the passage of Rayleigh waves.
- Define the phase and group velocity, and compute one from the other.
LEARNING MODE:
Studying textbook and other literature (including lecture notes), attending lectures, ending lectures, derivation of the equations and study of examples.
TEACHING METHODS:
Lectures, discussion, derivations of the equations, solving problems.
TERMS FOR RECEIVING THE SIGNATURE:
Positively graded (one) homework. Attendance at least 70% of classes (lectures and exercises).
EXAMINATION METHODS:
Knowledge is assessed through one homework assignment, two midterms, a written and an oral exam.
During the semester, students complete a homework assignment that is not graded, but must be successfully completed (a condition for signing). The teacher decides on the success of the assignment after reviewing it, and it must not contain a large number of incorrect statements and/or incorrect calculations.
The midterms and written exams consist of numerical and problem tasks from the course material. Attending the midterms is not mandatory, but successfully completed midterm (at least a passing grade) can replace the written exam, in such a way that the grade of the written exam represents the arithmetic mean of the midterm grades.
Grading criteria for the midterm and written exam (B = percentage of completion):
B < 40 % - insufficient (1)
40 <= B < 55 % - sufficient (2)
55 <= B < 70 % - good (3)
70 <= B < 85 % - very good (4)
B <= 85 % - excellent (5)
The oral exam consists of questions in which you need to define/describe/explain technical terms and derive equations from the course material.
The final grade will be calculated as the arithmetic mean of the written and oral exam grades.
LITERATURE (MANDATORY):
Lay, T., T. C. Wallace: Modern Global Seismology, Academic Press, San Diego, 1995.
Shearer, P.M.: Introduction to Seismology, Third Edition, Cambridge University Press, United Kingdom, 2019.
Stein, S. and M. Wysession: An introduction to Seismology, Earthquakes and Earth structure, Blackwell Publ., 2003.
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