Dr Ian Main
is currently a reader in seismology and rock physics at the University of Edinburgh. His main research interests are in earthquake physics, seismotectonics, seismic hazard and fluid-rock interactions. He gave the 1997 Bullerwell Lecture in geophysics, is a past member of the International Association of Seismology and Physics of the Earth's Interrior subcommission on 'modelling the earthquake source', and is a past board member of the International Seismological Centre governing council. He is currently associate editor for 'Journal of Geophysical Research' and 'Natural Hazards'.

Professor Robert J. Geller
is a seismologist at Tokyo University. His main research interests are numerical modelling of seismic wave propagation and inversion of observed seismic data to determine the 3-D structure of the Earth's interior. He has never attempted to predict earthquakes, and has been sceptical about prediction research since watching the rise and fall of the 1970s prediction boom at close-hand while a graduate student. His involvement in the debate on prediction began in 1991, with the publication of a Commentary in Nature (352, 275-276). Since then he has published extensively on this subject (see annotated bibliography). Please address reprint requests and other correspondence to bob@global.geoph.s.u-tokyo.ac.jp.

Professor Max Wyss
received a diploma in Geophysics from the Federal Institute of Technology, in Zurich, Switzerland and a Ph.D. in Seismology from the California Institute of Technology, in Pasadena, California. He is the chairman of the IASPEI (International Association of Seismology and the Physics of the Earth's Interior) sub-commission on earthquake prediction. Since 1991 he has occupied the Wadati Chair of Seismology at the Geophysical Institute of the University of Alaska, Fairbanks, where he studies problems of earthquake prediction, seismic hazard, asperities in fault zones, mapping of magma chambers beneath volcanoes and estimating stress orientations from fault plane solutions.

Dr Pascal Bernard
is a physicist specializing in seismology. He is director of the Laboratory of Seismogenesis in the Seismological Department of IPGP. For the last 15 years his research has been focussed chiefly on seismic sources, mainly from the seismological point of view, but also following a multidisciplinary approach for some large earthquakes thanks to the collaboration with geodesians and geologists. He has recently become the coordinator of the GAIA European project for the monitoring of crustal instabilities and earthquake precursors in the rift of Corinth, Greece.

Dr. Andrew Michael
has been a geophysicist with the U.S. Geological Survey's Earthquake Hazards Team in Menlo Park, California, since 1986. As an observational seismologist his research interests include structural constraints on earthquake rupture, the evolution of fault zones, interactions between earthquakes and stress, earthquake prediction including the Parkfield Earthquake Prediction Experiment, and the rapid dissemination of earthquake information. A graduate of MIT and Stanford University, he has taught at both Stanford and the University of California at Davis and is an associate editor of the Bulletin of the Seismological Society of America.

Professor Christopher Scholz
holds the chair of Earth Sciences at the Lamont-Doherty Earth Observatory of Columbia University. He is author of 'The Mechanics of Earthquakes and Faulting' (Cambridge, 1990), 'Fieldwork: a Geologist's Memoir of the Kalahari' (Princeton, 1997), and over 150 research articles. He was a developer, in the early '70's, of the dilatancy-diffusion theory of earthquake prediction - a theory which had a brief heyday but is no longer in fashion. He has not worked on earthquake prediction, as such, in the past 20 years.