Methods
As stated above, seismic tomography is typically solved as an inverse problem. In order to estimate P-wave velocity and further simplify seismic tomography, four main methods have been devised:
- Refraction traveltime tomography: Computationally simple but only reliable for making a shallow low resolution velocity structure. Within this method the observed data are the first arrival time, denoted as t: . The model parameters (s) are the slowness of the waves and L is the ray path matrix.
- Finite-frequency traveltime tomography: in an effort to obtain a higher resolution that the above method, the effects of wave diffraction are taken into account. Volumetric sensitivity kernels take the place of raypaths. Overall this allows the travel time and amplitude anomalies to be frequency-dependent, aiding the goal to increase resolution.
- Reflection traveltime tomography
- Waveform tomography : Uses seismic data to its fullest potential. Seismograms are the observed data and are controlled by the acoustic wave equation which serves as an approximation to the elastic wave propagation
Read more about this topic: Seismic Tomography
Famous quotes containing the word methods:
“The greatest part of our faults are more excusable than the methods that are commonly taken to conceal them.”
—François, Duc De La Rochefoucauld (1613–1680)
“Parents ought, through their own behavior and the values by which they live, to provide direction for their children. But they need to rid themselves of the idea that there are surefire methods which, when well applied, will produce certain predictable results. Whatever we do with and for our children ought to flow from our understanding of and our feelings for the particular situation and the relation we wish to exist between us and our child.”
—Bruno Bettelheim (20th century)
“A woman might claim to retain some of the child’s faculties, although very limited and defused, simply because she has not been encouraged to learn methods of thought and develop a disciplined mind. As long as education remains largely induction ignorance will retain these advantages over learning and it is time that women impudently put them to work.”
—Germaine Greer (b. 1939)