The source time function (STF) of the October 18, 1992 Colombia Ms=7.3 earthquake has been determined using long-period, teleseismic surface and body waveform data and the Empirical Green's Function (EGF) method. Love and SH waveforms of a Ms=6.7 foreshock were treated as the EGFs and deconvolved from the mainshock waveforms to obtain the relative STF. This indicated that the Ms=7.3 mainshock was a double event followed 100 seconds later by a large aftershock (not previously reported). The source durations for the mainshock and the aftershock are about 45 and 25 seconds, respectively. Based on the source radiation directivity, the rupture directions for the mainshock and aftershock are about S50¿W. The total length of the fault for the mainshock and aftershock is about 140 km, which agrees with the fault dimension estimated using the aftershock distribution. The seismic moment releases for the three asperities on the rupture surface are 1.0¿1019, 6.9¿1019, and 2.3¿1019 Nm, with respect to time. ¿ American Geophysical Union 1993