Measuring Moonquakes

Officially, the Apollo astronauts (AstroNOTs) left several seismographs on the moon surface, that were used to measure moonquakes. It seems several scientific papers were written on data from these devices.

If we assume that no men have ever landed on the moon, where did the data come from to analyze "moonquakes"? I guess there are a few possibilities:

1) the data was completely fabricated by someone at NASA

2) the seismographs were actually reading earth quakes, but were analyzed in the context of moon distances, topology, guesses about moon geology

3) seismographs were placed on the moon by unmanned missions to the moon

4) some bizarre, extremely covert deal with non-human entities who gave us seismograph data from the moon.

Any thoughts out there?