Ff. Pollitz, GRAVITY-ANOMALY FROM FAULTING ON A LAYERED SPHERICAL EARTH WITH APPLICATION TO CENTRAL JAPAN, Physics of the earth and planetary interiors, 99(3-4), 1997, pp. 259-271
The gravity anomaly resulting from mass redistribution from an earthqu
ake source (point dislocation) is re-explored in a spherical Earth geo
metry. Using a previously developed method of determining the Green's
functions for the static displacement field on a layered Earth, I obta
in the corresponding Green's functions for the perturbed gravitational
potential and gravity anomaly in a spherical harmonic expansion. The
synthesized gravity anomaly includes the effects of changes in the int
rinsic density distribution due to divergence of the displacement fiel
d and vertical displacement along level surfaces in density (stratific
ation displacement). Numerical examples of the Bouguer gravity anomaly
produced on a layered crustal model show that the contribution of int
rinsic density changes dominates over the contribution of stratificati
on displacement. Application to central Japan yields a new image of a
buried thrust structure suspected of having ruptured in the 1891 Nobi
earthquake.