Slow deformation and transmission of stress in the earth

A symposium entitled Slow Deformation and Transmission of Stress in the Earth was convened at the XIXth General Assembly Meeting of the International Union of Geodesy and Geophysics. This monograph is based on presentations made at that symposium which was held on the campus of the University of British Columbia in Vancouver, Canada on August 15th and 17th, 1987. The objective of the symposium was to engage geophysicists and geodesists in a discussion of the mechanisms, models, and measurements of slow deformations, and stress transmission in the Earths crust and mantle. These deformations are characterized by their quasi-static nature in which the effects of acceleration are negligible compared to those due to gravitational, rheological, thermal, chemical, and phase-change stresses. Phenomena such as tectonic plate motions, postglacial rebound, mantle convection, strain accumulation, aseismic strain release, and polar motion-induced deformations are included in this description. For many phenomena the effects of anelasticity and temporal nonlinearity are significant. This view of slow deformations is largely geophysical. From a geodetic point of view, however, the maintenance of accurate coordinates of points on the Earths surface requires that the geometry of ongoing deformation be taken into account [International Association of Geodesy, 1987]. This necessitates an understanding of the geophysical models of the temporal deformations and their predictive powers. Thus the symposium presenters were challenged to address such key issues as: the current stace of understanding of the phenomena of slow deformation and transmission of stress, contrasts between alternative models, applicability of geophysical models to prediction of positional changes, and assessment of model and parameter accuracies. These were formidable challenges and as such were pursued by only some of the authors.