AGU Fall Meeting 2006

Rotational Motions in Seismology

Seismology is based primarily on the observation and modelling of three-component translational ground motions. Nevertheless, theoretical seismologists (e.g., Aki and Richards, 1980, 2002) have argued for decades that the rotational part of ground motions should also be recorded. It is well known that standard seismometers are sensitive to rotations (just like tiltmeters are sensitive to translations). The lack of observations of rotational motions was mainly due to the limited resolution of rotation sensors. However, in the past few years ring lasers, fibre-optic gyros, and other measurement devices have led to the first significant and consistent observations of rotational motions suggesting that complete six-component measurements may be possible in the near future. Accurate measurements of rotational motions may have implications for (1) recovering the complete displacement history from seismometer recordings; (2) further constraining rupture properties; (3) extracting subsurface properties; and (4) providing additional information to earthquake engineers. The goal of this session is to discuss measurement devices, observations, modelling, theoretical aspects and potential applications of rotational ground motions. The session will be accompanied by the installation of an International Working Group on Rotational Seismology that aims at promoting investigations of all aspects of rotational motions in seismology and their implications for related fields such as earthquake engineering, geodesy, strong-motion seismology, tectonics, etc., and to share experience, data, software, and results in an open web-based environment. Further information can be found at www.rotational-seismology.org.

Chairs: H. Igel, M. Todorovska, W.H.K. Lee

Summary of Abstracts for Seismology Session S05:

Rotational motions in seismology