Inversion = Migration + Tomography
, by Peter Mora
Seismic inversion, broadly enough defined, is equivalent to doing
migration and reflection tomography simultaneously.
Diffraction tomography and inversion works best when sources
and receivers surround the region of interest, as in medical
imaging applications. Theoretical studies typically show that
the high vertical wavenumber velocity perturbations are resolved
in seismic reflection experiments where the
sources and receivers are restricted to the Earth's surface
but low wavenumbers
must be obtained using a separate step such as a velocity analysis or
reflection tomography.
I propose that an iterative inversion
using a varying background velocity obtains all wavenumbers that are resolvable separately by migration and tomography. (The background velocity must contain
abrupt discontinuities.)
Reflectors in the background model simulate sources
and receivers within the Earth so the source
and receiver coverage in seismic reflection inverse problems
is effectively the same as in medical imaging.
Some synthetic examples verify the theoretical predictions and
show that reflector locations and interval velocities can
be obtained simultaneously.
STANFORD