Seismic tomography

Seismic tomography

Seismic tomography is a methodology for estimating the earth's properties. In the seismology community, seismic tomography is just a part of seismic imaging, and usually has a more specific purpose to estimate properties such as propagating velocities of compressional waves (P-wave) and shear waves (S-wave). It can also be used to recover the attenuation factor Q. Another branch of seismic imaging is seismic migration in which the properties to be estimated include the reflection coefficient or reflectivity.

The simplest case of seismic tomography is to estimate P-wave velocity. Several methods have been developed for this purpose, e.g., refraction traveltime tomography, finite-frequency traveltime tomography, reflection traveltime tomography, waveform tomography.

Seismic tomography is usually formulated as an inverse problem. In refraction traveltime tomography, the observed data are the first-arrival traveltimes t and the model parameters are the velocity v. The forward problem can be formulated as:t = Lvwhere L is the forward operator which, in this case, is the raypath matrix.Refraction traveltime tomography is computationally efficient but can only provide a low-resolution image of the subsurface.

To obtain a higher-resolution image, waveform tomography has been developed. In this case, the seismograms are the observed data. The forward model is usually governed by the acoustic wave equation. This is an approximation to the elastic wave propagation. Elastic waveform tomography is much more difficult than acoustic waveform tomography. The acoustic wave equation is numerically solved by some numerical schemes such as finite-difference and finite-element methods.

References

* Stewart, R. R., "Exploration Seismic Tomography: Fundamentals", Society of Exploration Geophysicists, 1991

ee also

* seismology
* seismograph


Wikimedia Foundation. 2010.

Игры ⚽ Нужно сделать НИР?

Look at other dictionaries:

  • seismic tomography — seismic tomography, the use of seismic waves to form images of the earth s interior which are then synthesized into a single cross sectional view: »the three dimensional maps produced by seismic tomography …   Useful english dictionary

  • seismic tomography — seisminė tomografija statusas T sritis Standartizacija ir metrologija apibrėžtis Žemės mantijos nevienalytiškumo radimo būdas matuojant seisminių bangų sklidimo įvairiomis kryptimis greičių ir dažnių pokyčius. atitikmenys: angl. seismic… …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

  • Tomography — Basic principle of tomography: superposition free tomographic cross sections S1 and S2 compared with the projected image P Tomography refers to imaging by sections or sectioning, through the use of any kind of penetrating wave. A device used in… …   Wikipedia

  • tomography — [tə mäg′rə fē] n. 〚< Gr tomos, a piece cut off (see TOMY) + GRAPHY〛 a process for producing an image of a single plane of an object excluding all other planes, as by using CT SCAN or ULTRASOUND, in …   Universalium

  • tomography — [tə mäg′rə fē] n. [< Gr tomos, a piece cut off (see TOMY) + GRAPHY] a process for producing an image of a single plane of an object excluding all other planes, as by using CT SCAN or ULTRASOUND, in diagnostic medicine, seismic surveys, etc …   English World dictionary

  • Geophysical Tomography Group — The Geophysical Tomography Group was part of the Institut de Physique du Globe de Paris (Jussieu Campus). During the years 1985 2000 it made pioneering developments in the domain of nonlinear fitting of seismic waveforms. Many of the past members …   Wikipedia

  • Outline of geophysics — Seismic velocities and boundaries in the interior of the Earth sampled by seismic waves. The following outline is provided as an overview of and topical guide to geophysics: Geophysics – the physics of the Earth and its environment in space; also …   Wikipedia

  • Earth Sciences — ▪ 2009 Introduction Geology and Geochemistry       The theme of the 33rd International Geological Congress, which was held in Norway in August 2008, was “Earth System Science: Foundation for Sustainable Development.” It was attended by nearly… …   Universalium

  • Mantle plume — A superplume generated by cooling processes in the mantle.[1] A mantle plume is a hypothetical thermal diapir of abnormally hot rock that nucleates at the core mantle boundary and rises through the Earth s mantle. Such plumes were invoked in 1971 …   Wikipedia

  • Near-surface geophysics — is the use of geophysical methods to investigate small scale features in the shallow (tens of meters) subsurface. It is closely related to applied geophysics or exploration geophysics. Methods used include seismic refraction and reflection,… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”