A computer-implemented method for determining a subsurface feature, includes: determining a first velocity model based on an initial velocity model; generating a second velocity model based on measured seismic data at one or more first frequencies, the first velocity model, and a full waveform inversion (FWI); and in response to the second velocity model not satisfying a preset condition, performing a seismic forward simulation on the second velocity model to generate simulated seismic data at one or more second frequencies lower than the one or more first frequencies; updating the first velocity model based on the simulated seismic data at the one or more second frequencies; and updating the second velocity model based on the measured seismic data at the one or more first frequencies, the updated first velocity model, and the FWI, to determine the subsurface feature.