New developments for a unified theory of P-SV and SH vibrations in layered media: exact flattening transformations, fast methods for computing synthetic seismograms, properties of surface waves, effective inversion procedure

Información del proyecto

Identificador del acuerdo de subvención: INTAS-RFBR95-0865

Fecha de inicio

Fecha de finalización

Financiado con arreglo a

• International Association for the promotion of cooperation with scientists from the independent states of the former Soviet Union (INTAS), 1993-

Coste total

Sin datos

Aportación de la UE

Sin datos

Coordinado por

Université Joseph Fourier
France

Objetivo

This project will develop a unified theory of Love-type and Rayleigh-type vibrations in plane, spherically and cylindrically layered elastic media. Algorithms and computer programmes for the forward and inverse modeling of P (primary), SV (secondary vertical) and SH (secondary horizontal) wave propagation will also be devised.

All these vibrations can be described as solutions of Sturm-Liouville equations: in scalar form the Love waves and in matrix form for Rayleigh waves. The common features of these equations allows the project to find an exact solution to the long standing "Earth flattening" problem for P-SV vibrations. By using the Sturm-Liouville representation, many explicitly integrable cases can also be found for the Rayleigh-type equations in heterogeneous media. The classical reflectivity algorithm can thus be extended to include piecewise heterogeneous layers. This approach results in a considerable reduction of the computation time in media with velocity gradients. The same representation makes it possible to solve the inverse problem efficiently: it allows to estimate the elastic parameters and density as a function of depth from the characteristics of Love and Rayleigh surface waves at a fixed frequency. The inversion of Rayleigh waves is interconnected with the mathematical study of the spectrum of the related boundary value problem.

The main objectives of the project are, therefore, to carefully study the properties of the exact Earth flattening transformation and to write the corresponding computer programme, to develop a programme for the fast computation of synthetic seismograms and to test its accuracy, and to explore the possibilities of monochromatic surface waves inversion and its extension to full waveform inversion.

The methods described above will be applied to the following seismological problems:
the study of the mantle discontinuities and core-mantle boundary;
the determination of the earthquake source mechanisms;
the modelling of the spheroidal oscillations of the Earth;
the inversion of seismological data with a monochromatic source and as an iterative full waveform procedure.

The research results will be presented as scientific papers in international journals as well as computer programmes for the forward and inverse modeling of seismic wave propagation in layered media which will serve to test the feasibility and numerical stability of the methods and algorithms mentioned above.

Programa(s)

• IC-INTAS - International Association for the promotion of cooperation with scientists from the independent states of the former Soviet Union (INTAS), 1993-

Tema(s)

• 5 - Earth Sciences, Environment, Energy

Convocatoria de propuestas

Datos no disponibles

Régimen de financiación

Datos no disponibles

Coordinador

Université Joseph Fourier

• Aportación de la UE: Sin datos
• Dirección: 38041 Grenoble ; Francia
• Coste total: Sin datos

Participantes (1)

International Institute of Earthquake Prediction Theory and Mathematical Geophysics

Rusia

• Aportación de la UE: Sin datos
• Dirección: 113556 Moscow
• Coste total: Sin datos