Geologically and petrophysically constrained synthetic random velocity
fields are important tools for exploring (through the application
of numerical codes) the seismic response of small-scale lithospheric
heterogeneities. Statistical and geophysical analysis of mid- and
lower-crustal exposures has demonstrated that the probability density
function for some seismic velocity fields is likely to be discrete
rather than continuous. We apply the term ''modal'' fields to describe
fields of this sort. This letter details a methodology for generating
synthetic modal fields which satisfy the von Karman covariance function.
In addition, we explore some of the mathematics of ''modality'',
and define a modality parameter which quantifies the variation between
end members binary and continuous fields.