Abstract

The emergence of rotational seismology in the last two decades was enabled by technological advances in large-scale ring laser gyroscope technology and later the first field deployable rotation sensors. Six degree-of-freedom observations of the seismic wavefield at a single station provides insights similar of a seismic array. The operation and observations of the G-ring and ROMY as two unique ring lasers are discussed. A first low noise model for rotational ground motions, based on a conversion of acceleration to rotation is presented. Available observations are compared to validate the model. Towards long periods, atmospheric pressure waves excite rotational motions at the surface. The admittance for direct rotational observations are estimated and used to constrain  low noise limits for ROMY at long periods.