Ground tilt seismic spectrum measured with a new high sensitivity rotational accelerometer

We describe a new rotational accelerometer exhibiting excellent rotational acceleration sensitivity of ${\text{2–3×10}}^{\text{−9}}$ ${\mathrm{rad\hspace{0.17em}s}}^{\mathrm{-2}}\mathrm{/\surd Hz}$ for frequencies below 2 Hz and increasing as the square of frequency for frequencies higher than 2 Hz. The sensitivity to horizontal linear accelerations and static tilts is 60 dB less than its rotational sensitivity. The accelerometer has been used to characterize the seismic ground tilt spectrum. Measurements of the performance of the device and of the seismic rotational spectrum are presented.