The characterization of the equivalent elastic source for a small (253 lb TNT) chemical explosion detonated in alluvium is given. The representation is constrained by a well-known propagation path. Data from the nonlinear region (<215 m/kt1/3) are used in interpreting the moment tensor representation. The results of this study are: (1) the applicability of frequency domain moment tensor representation is shown; (2) the source is composed of two parts—the initially spherical explosion followed by the cylindrically symmetric spall; and (3) the deviatoric source components are an order of magnitude smaller than the spherical explosion and cylindrical spall contributions. The spherical explosion is shorter in duration (50 to 80 msec) than the spall source (200 msec), which is delayed in time. The initial explosion can be modeled by the isotropic moment tensor while the spall source is represented as the moment tensor elements with the ratio: M11 = 1; M22 = 1; and M33 = 2. Comparison of these results with those from nuclear explosions suggests that similar phenomena occur in these cases also.