tapping test on SQZ bench

We installed our Trillium seismometer on the floor (next to the TAEC, picture 1) and the Meggit accelerometers on the SQZ bench along the south edge (picture 2). Data were acquired with the Centaurus.
We performed some tapping test in order to identify the resonances of the bench. On the attached plots x stands for the NS direction, y for the EW and z for the vertical.

- when tapping along NS we excited the 10,4 Hz peak (plot 3 shows the spectra during the tapping along the 3 directions)
- when tapping along EW we excited the 14,2 Hz peak (plot 4)
- when tapping along the vertical direction we excited a broad peak at 41.8 Hz and another broad bump around 84Hz, but not very clear (plot 5)

We also performed a switch off test of the fans over the SQZ bench. As you can see from plot 6, it doesn't seem to make any difference along the z direction

The last plot shows the FFTs of the accelerometers on the SQZ bench while excited and the ones of the seismometer on the floor. All 3 directions are shown together. It would be useful to compute the transfer functions between them.

In conclusion: 10,4 and 14,2 Hz are resonances of the SQZ bench, and the fan over it doesn't seem to create any excitation.