The multichannel singular spectrum analysis (MSSA) reconstruction algorithm denoises and reconstructs seismic traces on a regular grid. We have developed a modified version of MSSA that can cope with denoising and reconstruction of traces with irregular coordinates. The proposed method, interpolated multichannel singular spectrum analysis (I-MSSA), connects off-the-grid observations to the desired gridded data via a linear interpolation operator. The algorithm consists of two steps. In the first step, we use the steepest-descent method to estimate the gridded data that honors off-the-grid observations. The second step guarantees convergence to a solution by applying the MSSA filter to the gridded data. The final solution is the reconstructed volume that honors off-the-grid observations. We use the algorithm to process synthetic and field data. We also provide an application in which 3D prestack data corresponding to an orthogonal survey are fully reconstructed using cross-spread gathers. We use I-MSSA to restore each subset individually. The output is a complete seismic volume described in a regular common-midpoint grid.