We investigated the rupture process of the 1999 D¿zce Earthquake by applying the multi time-window linear waveform inversion method to low-frequency ground motions (≤0.5 Hz) in the near source area. Then, we performed the forward modelling of higher frequency ground motions (0.3--10.0 Hz) by the Empirical Green's Function (EGF) method to image the strong motion generation area (SMGA). We also examined the source model to check whether the supershear phenomenon occurred inside the asperities or not. Slip distribution model from the inversion suggests 2 asperities. The maximum slip is obtained as 5 m near the hypocenter. The high first time window front propagation velocity (FTWFPV) and consequently, high apparent rupture velocity found from the investigation of rupture progression indicated that eastern propagation partially showed supershear behaviour. The EGF simulation, which identifies an average rupture velocity (Vr) in SMGA, supports this finding.