Comprehensive Processing of the Apollo Lunar Seismic Event Data

The Apollo Passive Seismic Experiment consisted of four seismic stations deployed on the lunar surface between 1969 and 1972. Data were recorded continuously from deployment until 1977. Previous studies often used only small subsets of all the available data due to computational limitations. In our study, event data (lunar seismic signals detected in the continuous time series) in their entirety are converted into a standard format for seismological analysis. The IRIS Data Management Center provided data to us in their original format on nine 8mm Exabyte cartridges (eight event tapes and one supplementary tape). The total disk usage of the event data after conversion to two-byte integers is 13 Gb. Events have been previously classified into three types: deep moonquakes, shallow moonquakes, and impacts. The tapes from the IRIS DMC contain just under 11,000 events the bulk of the approximately 12,000 catalogued events. Several programs to view and filter the data are used to improve data quality. Data with various irregularities (timing errors, telemetry problems) are corrected or removed. These modifications allow for modern processing techniques to be applied consistently to the remaining data. Based on our preliminary analyses we estimate 97.6 % of the data will be useable for further study. This work will permit a range of investigations, using stacking techniques that do not require waveform coherence. The poor signal-to-noise ratio of the lunar seismograms renders conventional automatic detection methods (used for terrestrial seismic events) ineffective for these data. Using recently-developed stacking techniques and our processed version of the data, we will focus on better identification and cataloguing of moonquakes and on estimating lateral variability in scattering properties of the lunar regolith.