Systems, methods, and software for detecting boundary locations of multiple subsurface layers are described. In some aspects, the boundaries of multiple subsurface layers in a subterranean region are identified based on measurements associated with multiple different transmitter-receiver spacings. The measurements are generated based on operating multiple transmitters and multiple receivers of a resistivity logging tool at a tool depth in a wellbore in the subterranean region. A first pair of the subsurface boundary locations are determined based on a first measurement associated with a first transmitter-receiver spacing. A second, different pair of the subsurface boundary locations are determined based on a second measurement associated with a second, longer transmitter-receiver spacing. The first pair of subsurface boundary locations reside between the second pair of subsurface boundary locations in the subterranean region.