Implementations of various technologies for a method for generating a seismic image of a subsurface are described herein. Seismic data may be received from two sensors in a seismic survey. The seismic data below and equal to a predetermined frequency may be classified as low-frequency seismic data. The low-frequency seismic data may be re-sampled based on the predetermined frequency. A set of low-frequency Green's functions may be calculated using interferometry on the re-sampled low-frequency seismic data. High-frequency seismic data of the seismic data may be processed to create a set of high-frequency Green's functions at one or more source locations of the seismic survey. The set of high-frequency Green's functions may be merged with the set of low-frequency Green's functions to create a set of broad-band Green's functions. The seismic image may be generated using the set of broad-band Green's functions at the source locations.