The materials in this archive are organized as follows:1) "katla" directory contains: - the processed seismograms (local earthquakes removed, decimated to a sampling rate of 10 Hz) in the "seismograms" directory - the correlation envelopes used in the real-data example (tremor at Katla volcano) in the "covariograms" directory - the MATLAB scripts to generate the correlation envelopes from the processed seismograms2) "synthetic" directory contains: - the MATLAB scripts to generate synthetic data used in the synthetic tests