Mechanical and electromagnetic phenomena accompanying pre-seismic deformation: From laboratory to geophysical scale

Mechanical and electromagnetic phenomena accompanying pre-seismic deformation: From laboratory to geophysical scale The idea of this Special Issue originated from a topical session held on “Mechanical and Electromagnetic Phenomena Accompanying Preseismic Deformation: from Laboratory to Geophysical Scale” convened at the General Assembly of the European Geosciences Union, in Vienna in April 2004. The plan of the Special Issue was to bring together researchers from different fields to address a variety of questions in earth sciences. The mature wisdom of any science is determined by its ability to predict phenomena under study. A vital problem in material science and in geophysics is the identification of precursors of macroscopic fractures or shocks. But earthquakes are nothing but physical phenomena and science should have some predictive power on the future behavior of any physical system. The degree to which we can predict a phenomenon is often measured by how well we understand it. Despite the large amount of experimental data and the considerable effort that has been undertaken by the material scientists, many questions about fracture processes remain standing. In spite of almost a century of research since the standard rebound theory of earthquakes was formulated, the complex nature and many aspects of earthquake phenomenology still escape our full understanding and are reflected in the disappointing progress on earthquake prediction. In recent years, the wind prevailing in the scientific community does not appear to be favorable for earthquake prediction research, in particular for the research on short-terms prediction. Sometimes the arguments were extended to the extreme claim as to the impossibility of any precursory activity. This was due to the fact that in the last decades the study of seismic precursors was expected to give rise in a relatively short period of time to earthquake prediction. But the physics of earthquakes has demonstrated to be a very complicated matter. Considering the difficulties associated with such factors as the highly complex nature, rarity of large earthquakes and subtleties of possible pre-seismic signatures, the present negative views are not groundless. It is difficult to prove associations between any two events (possible precursor and earthquake) separated in time. However, it is more difficult to prove their association groundless. In spite of this uncertainty of the scientific community, research with aim at giving the possibility to predict earthquakes in future continue with a critical view and with new ideas and deep investigations. Recent progress in this topic has been largely due not only to the increased amount and accuracy of ground field measurements, careful attention to errors in data, and improved understanding of earthquake source mechanics but also, and may be first of all, in a new approach including observations from space.Within this framework, an earthquake is considered as a coupling element between Earth and near-Earth space. Observations a posteriori of different ground and space seismic precursors as well as laboratory experiments on rock samples and the development of theoretical models, aim at seeing in perspective the phenomenon “earthquake” within the framework of a unified theory able to explain the causes of its genesis, and the dynamics, rheology, and micro-physics of its preparation, occurrence, post-seismic relaxation, and inter-seismic phases. The physical system to be considered including solid Earth and near-Earth space with related couplings and perturbations. Also a better scientific coordination on an international basis between diverse teams of researchers would be hoped to smooth and integrate different methodological approaches relatively to each other and for a better use of the different competences, instruments, and databases. Tectonophysics 431 (2007) 1–5 www.elsevier.com/locate/tecto 0040-1951/$ - see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.tecto.2006.10.001