Deep Earth rotational seismology

Rotational seismology opens a new avenue to study the deep interior of the Earth. Using data from the Wettzell Observatorium, Germany, where a ring laser gyroscope and a 3-component translational broadband seismometer are co-located, we report the presence of clear S, ScS and SdS signals on both rotational and translational seismograms. Using S wave arrivals, we propose a new methodology to extract information on velocity changes in the Earth mantle and we show that, by combining both translational and rotational data, we are able to solve the well known velocity-depth ambiguity inherent to classical inverse problems. The methodology is validated using ray theory and 2.5-D finite-difference synthetics. We provide a proof-of-concept showing that future studies of the Earth's deep interior can be improved by combining translational and rotational records.