Deep underground rotation measurements: GINGERino ring laser gyroscope in Gran Sasso

GINGERino is a large frame laser gyroscope investigating the ground motion in the most inner part of the underground international laboratory of the Gran Sasso, in central Italy. It consists of a square ring laser with a \(3.6\) m side. Several days of continuous measurements have been collected, with the apparatus running unattended. The power spectral density in the seismic bandwidth is at the level of \(10^{-10} \rm{(rad/s)/\sqrt{Hz}}\). A maximum resolution of \(30\,\rm{prad/s}\) is obtained with an integration time of few hundred seconds. The ring laser routinely detects seismic rotations induced by both regional earthquakes and teleseisms. A broadband seismic station is installed on the same structure of the gyroscope. First analysis of the correlation between the rotational and the translational signal are presented.