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INVERSE THEORY APPLIED TO MULTI‐SOURCE CROSS‐HOLE TOMOGRAPHY.
Author(s) -
PRATT R. GERHARD
Publication year - 1990
Publication title -
geophysical prospecting
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.735
H-Index - 79
eISSN - 1365-2478
pISSN - 0016-8025
DOI - 10.1111/j.1365-2478.1990.tb01847.x
Subject(s) - propagator , a priori and a posteriori , inverse problem , wave equation , frequency domain , inversion (geology) , bandwidth (computing) , regional geology , inverse , physics , mathematical analysis , optics , computational physics , computer science , geology , telecommunications , mathematics , geometry , hydrogeology , seismology , tectonics , philosophy , geotechnical engineering , epistemology , metamorphic petrology , quantum mechanics
A bstract It is advantageous to consider inversion of multi‐source (wide‐aperture) cross‐hole data using methods that (i) are based on the wave equation rather than its high‐frequency ray approximation, and (ii) use the full information content of the recorded wavefield rather than only first‐arrival times. Wave‐theoretical methods require the ability to forward‐model appropriate wave equations for all source positions in arbitrary reference media. This can be achieved using a frequency‐domain elastic wave propagator that facilitates the modelling of multi‐source data at the cost of temporal bandwidth. The trade‐off is deliberate; the propagator is applied to the cross‐hole imaging problem, in which wide spatial bandwidths are more important than temporal bandwidth. By using the frequency‐domain propagator, non‐linear inverse techniques are applied to data from a very large number of source positions. The method can be applied in 2D media of arbitrary a priori complexity. In a synthetic example, compressional and shear‐velocity perturbations are successfully resolved with one iteration using only a single frequency component of wide‐aperture elastic wave cross‐hole data.