Sismologie: modèles de Terre

Sismologie: modèles de Terre
Diplôme d'ingénieur de l'École et observatoire des sciences de la Terre (EOST)Parcours Diplôme d'ingénieur de l'EOST

ComposanteÉcole et observatoire des sciences de la Terre (EOST)

Description

Cette unité d’enseignement décrit la théorie classique de la propagation des ondes élastiques dans les milieux isotropes sphériques et aborde le problème de leur atténuation. Il considère acquis les bases de la théorie de l’élasticité et celles de la propagation des ondes de volume en milieux isotropies planes. Il traite les ondes de volume (théorie des rais et hodochrones en géométrie sphérique), les ondes de surface (propriétés, dispersion), les modes propres, l’atténuation intrinsèque, la diffusion.

This teaching unit describes the classical theory of elastic wave propagation in spherical isotropic media and addresses the problem of their attenuation. It revises the basics of the theory of elasticity and of the propagation of volume waves in plane isotropic media, then treats in more detail body waves (ray theory and travel-time curves in spherical geometry), surface waves (properties, dispersion), normal modes, intrinsic attenuation, and scattering.
 

Compétences visées

Les ondes élastiques émises par les séismes se propagent à travers l’ensemble du Globe et sont influencées par sa structure. L’objectif de l’UE est double : d’une part de comprendre comment la structure de la Terre influence les ondes sismiques et d’autre part d’extraire des informations sur la structure simplifiée de la Terre à partir des enregistrements des ondes sismiques.

The elastic waves emitted by earthquakes propagate through the entire globe and are influenced by its structure. The objective of this course is twofold: to understand how the structure of the Earth influences seismic waves and to extract information about the simplified structure of the Earth from seismic wave records.

A la fin de cet enseignement, vous serez capable de :

  • Identifier les différentes ondes sismiques sur un sismogramme et sur un hodochrone expérimental et relier ce dernier avec la structure 1D de la Terre
  • Dessiner et exploiter les courbes de dispersion de vitesses de phase et de groupe des ondes de surface.
  • Caractériser les modes propres principaux de la Terre
  • Différentier les effets de l’atténuation intrinsèque et de la dispersion géométrique.
  • Identify the different seismic waves on a seismogram and on an experimental travel-time curve and relate the latter to the 1D structure of the Earth
  • Draw and exploit the phase velocity and group dispersion curves of surface waves.
  • Characterize the main normal modes of the Earth
  • Differentiate the effects of intrinsic attenuation and geometric dispersion.

School regulations

The curriculum includes three years of study: admissions, the organisation of studies, assessments, placements and vivas, graduation and international exchanges are all explained in the current school rules (pdf).

First and second year courses

First and second year courses

  • General modules: mechanics, geology, mathematics, IT, digital analysis, signal processing, inverse methods.
  • Geophysical methods: physics of the Earth, seismology, seismic modelling and imaging, geodesy, gravimetry, potential methods, geomagnetism, electromagnetism, rock physics and fracture, hydrology.
  • Practical work: geophysical measurements in the field (photo) and in the laboratory, geology field placements in the Alps.
  • Languages and economic and social sciences: English, modern language 2, economics, industrial property, management, sustainable development, ethics, quality, company health and safety
  • IT and research projects, shared with the first year of the master’s degree
  • Summer placements at a laboratory or company, with numerous opportunities abroad (international placement contact: Mike Heap)

Third year course

Students have a choice of 3 specialisations in the third year:

  • Geophysics applied to the exploration and production of raw materials: seismic and hydrodynamic characterisation of reservoirs, seismic processing and interpretation, potential methods.
  • Geophysics applied to geotechnics: geotechnics and the resistance of materials applied in civil engineering, geomechanics, hydrogeophysics, electromagnetic methods, earthquake.
  • Hydrogeology, hydrogeochemistry, hydrogeophysics (HydroG3).

Additional teaching:

  • Languages and economic and social sciences: English, energy economy, company strategy and structure.
  • Geophysics field camp in Alsace (photo).  Here are images of a normal fault in the Rhine Graben taken by students.
  • 6-month industry placement culminating in the writing of a dissertation and a viva before a jury in order to obtain the engineering degree. The placements are carried out all over the world.