This paper is devoted to a geostatistical attempt at modeling migration err
ors when localizing a reflector in the ground. Starring with a probabilisti
c velocity model and choosing the simple geometrical optics background for
the wave propagation in such media, we give the expression of the errors. T
his,nay be quantified provided the covariance of the velocity field is know
n. Variance of arrival times at constant offset is related to the covarianc
e of the velocity field at hand A practical application is given in the sa,
ne paragraph. After that we give a typical schema for migration and uncerta
inty modeling: starling with seismic data, we make the weak seismic inversi
on. We then obtain the covariance of the velocity field that,we use for sim
ulating migration errors. The main issues of this methodology are discussed
in the last paragraph.