A method for estimating surface wave coda in seismic data recorded with a data acquisition system over an underground formation, the method comprising: defining a first time-reversal mirror including a target source and one or more other sources of the data acquisition system, and a second time-reversal mirror including a target receiver and one or more other receivers of the data acquisition system; characterized in that the method further comprises: using the first time-reversal mirror to simulate first time-reversal experiments on an input dataset representative for the seismic data, to obtain estimates of surface waves traveling from the other receivers to the target receiver; muting each of the estimates and each surface wave trace from the target source to one of the other receivers in the second time-reversal mirror, up to a respective coda start time, to obtain a computed coda dataset; and using the second time-reversal mirror to simulate second time-reversal experiments on the computed coda dataset, to obtain a coda estimate for a surface wave travelling from the target source to the target receiver, wherein the coda estimate is then used to obtain information about a near-surface layer and/or remove coda from the seismic data before processing to extract structural information about the underground formation. defining a first time-reversal mirror including a target source and one or more other sources of the data acquisition system, and a second time-reversal mirror including a target receiver and one or more other receivers of the data acquisition system; characterized in that the method further comprises: using the first time-reversal mirror to simulate first time-reversal experiments on an input dataset representative for the seismic data, to obtain estimates of surface waves traveling from the other receivers to the target receiver; muting each of the estimates and each surface wave trace from the target source to one of the other receivers in the second time-reversal mirror, up to a respective coda start time, to obtain a computed coda dataset; and using the second time-reversal mirror to simulate second time-reversal experiments on the computed coda dataset, to obtain a coda estimate for a surface wave travelling from the target source to the target receiver, using the first time-reversal mirror to simulate first time-reversal experiments on an input dataset representative for the seismic data, to obtain estimates of surface waves traveling from the other receivers to the target receiver; muting each of the estimates and each surface wave trace from the target source to one of the other receivers in the second time-reversal mirror, up to a respective coda start time, to obtain a computed coda dataset; and using the second time-reversal mirror to simulate second time-reversal experiments on the computed coda dataset, to obtain a coda estimate for a surface wave travelling from the target source to the target receiver, wherein the coda estimate is then used to obtain information about a near-surface layer and/or remove coda from the seismic data before processing to extract structural information about the underground formation.