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
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