The last day LHO has been suffering from high microseism, so we've had lots of time to ponder ground motion. JeffK noticed a seeming inconsistency on the DetChar summary pages, that maybe someone can clear up for us. The ASD for H1 ground motion last night seems has a microseism peak in Z at about 5 microns, but the BLRMS for that period indicates that the motion is about a micron, a factor of 5 disagreement. Attached pictures are screenshots of the Detchar page for last night, first is the ASD, second is the BLRMS. This could be partly because the two measures are calculated for different measures of amplitude, peak vs peak-to-peak vs RMS. But I think that at best explains a factor of 2 difference, not 5.
The ASD has units of m/rt(Hz), so to get RMS value, you have to multiply by square root of the frequency of interest. So 5 micron/rt(Hz at 0.1 Hz gives an RMS of ~1.5 micron.
There is also the problem of velocity versus displacement measurement, but since f is nearly 0.16 Hz, it doesn't make much difference.