Rotational Seismology: Review of Achievements and Outlooks

Rotational seismology is a relatively new area of science. Rotational seismology could be applied in a wide range of seismology disciplines, including strong-motion and broadband seismology, earthquake engineering, earthquake physics, seismic instrumentation, and seismic hazards. Rotational seismology is also of interest to physicists conducting research in Earth-based observatories for detecting gravitational waves. Modern acquisition technology, such as fiber-optic or ring laser gyros, allow the actual observation of rotational motions; these observations are becoming consistent with collocated recordings of translational ground motions. However, often even seismologists have questions: What does rotational seismology mean, what hardware does it rely on, what can it give now, and what can it achieve? How could measurements of rotational ground motions be applied to traditional seismology and related fields in the earth sciences? The study of rotational motions at teleseismic distances in the near field of engineering seismology requires different approaches, equipment, and methods. In this review, we briefly highlight these issues, focusing on the prospects for future research and seismic instruments used in rotational seismology.