Recent Advances in Rotational Seismology

Abstract

Rotational seismology is an emerging field of study concerned with all aspects of rotational motions induced by earthquakes, explosions, and ambient vibrations. Two recent monographs (Teisseyre et al. 2006; Teisseyre et al. 2008) and a Bulletin of the Seismological Society of America special issue on Rotational Seismology and Engineering Applications (Lee, Celebi et al. 2009) are useful starting points. Rotational seismology is of interest to a wide range of disciplines, including various branches of seismology, earthquake engineering, and geodesy, as well as to physicists using Earth-based observatories for detecting gravitational waves generated by astronomical sources, as predicted by Einstein in 1916. Traditionally, only translational ground motions are observed in seismology. However, we should also measure the three components of rotational motion and the six or more components of strain (Lee, Celebi et al. 2009). We will improve our understanding of the earthquake process (and the complex ground motions it generates) by developing new processing and inversion schemes including the new observables in rotations and strains. In this article we provide a summary of recent activities, some background information, and selected highlights of advances in rotational seismology and engineering applications. Following Hudnut (2005) on integrating real-time GPS with inertial sensors (including both translation and rotational), W. H. K. Lee (with K. W. Hudnut and J. R. Evans as coordinators) organized a mini-workshop on rotational seismology on February 16, 2006 (Evans et al. 2007). After the workshop, Evans and Lee contacted other groups active in rotational motions in several countries. An international working group on rotational seismology (IWGoRS) was then organized to promote investigations of rotational motions and their implications and to share experience, data, software, and results in an open Web-based environment (Todorovska et al. 2008). Anyone can join IWGoRS at http://www.rotational-seismology.org, subscribe to the mailing list, and contribute …