Reciprocity is applied to the situation where numerical simulations are nee
ded for a number of source locations but relatively a few receiver position
s. By invoking source-receiver reciprocity, the number of simulations can b
e generally reduced to three times the number of receiver positions. The pr
ocedure is illustrated for a heterogeneous medium with both single-force an
d double-couple sources. The numerical tests using a finite-difference impl
ementation show that the reciprocal simulations can be performed with the s
ame level of accuracy as the forward calculations.