Boris Gurevich is an SEG Honorary Lecturer for Pacific South in 2019 This year, geophysics Professor Boris Gurevich of Curtin University and CSIRO has been appointed Society of Exploration Geophysicists (SEG) Honorary Lecturer for Pacific South. The SEG Honorary Lecture programme, funded by Royal Dutch Shell through SEG Foundation, sponsors up to six lecturer tours each year, available on location in major regions around the globe or online. Each year Honorary Lecturers are nominated by the vote of the SEG Distinguished Lecture Committee. Quoting from the SEG procedures,“The Honorary Lecture program focuses on transfer of knowledge within a region and/or topic, recognizing prominent geophysicists and strengthening the services that SEG provides to an expanding global membership”. In her nomination letter to Prof Gurevich, SEG President Nancy J. House says that he had been chosen for this special honour because he is an outstanding communicator of ideas and an individual noted for quality in his contributions to geophysics. Boris’s lecture tour is taking place in March-June 2019. He toured Australia from 13 to 28 March, giving lectures to ASEG state branches in Perth Canberra, Brisbane, Sydney, Melbourne, Adelaide and Hobart. His lecture tour is also taking Boris to Singapore, Taiwan, China, Japan, Indonesia and Malaysia. The Australian leg of the tour was co-sponsored by ASEG, as well as by kind donations from CGG and DUG, and organised by Dr Marina Pervukhina, the ASEG’s Professional Development and Branch Liaison coordinator. Boris Gurevich has an MSc in geophysics from Moscow State University (1976) and PhD from Institute of Geosystems, Moscow, Russia (1988), where he began his research career (1981–1994). Between 1995 and 2000 he was a research scientist at the Geophysical Institute of Israel, where he focused mainly on seismic diffraction imaging problems. Since 2001 he has been a Professor of geophysics at Curtin University and advisor to CSIRO (Perth, Western Australia). At Curtin he has served as Head of Department of Exploration Geophysics (2010–2015) and, since 2004, as Director of the Curtin Reservoir Geophysics Consortium. He has served on editorial boards of a number of scientific journals, is a Fellow of the Institute of Physics and has over 100 journal publications in the areas of rock physics, poro- elasticity, seismic theory, modelling, imaging and monitoring of CO2 geo- sequestration. The SEG/ASEG Honorary Lecture tour highlights Boris’s Australian career. Boris has worked with Curtin and CSIRO for the last 19 years, during which he has built a world leading rock physics team. He continues to inspire new generations of geophysicists down under. Boris is available for professional discussions and mentoring opportunities. He can be reached at B.Gurevich@curtin.edu.au Seismic attenuation, dispersion and anisotropy in porous rocks – an overview The topic of Boris Gurevich’s Honorary Lecture is“Seismic attenuation, dispersion and anisotropy in porous rocks: Mechanisms and models”. Understanding and modelling of attenuation and dispersion of elastic waves in fluid-saturated rocks is important for a range of geophysical technologies that utilise seismic, acoustic or ultrasonic waveforms and amplitudes. In particular, in seismic oil and gas exploration, lateral variations of the attenuation in the overburden can distort seismic reflection amplitudes from exploration targets, leading to errors in reservoir characterisation. Conversely, seismic attenuation is ultimately controlled by subsurface properties and is thus increasingly used as an attribute for subsurface characterisation. Understanding the nature of seismic attenuation and its dependence on rock properties can make this characterisation more quantitative and robust. A key mechanism of seismic wave attenuation and dispersion in fluid- saturated rocks is viscous dissipation due to the flow of the pore fluid (relative to the solid frame) induced by the passing wave. Such fluid flow (or pressure relaxation), known by an acronym WIFF (Wave-Induced Fluid Flow) can take place on various length scales. Wavelength-scale fluid pressure relaxation between peaks and troughs of a passing wave is known as global or macroscopic flow and is described by Biot’s theory of poro-elasticity. WIFF caused by spatial variations of matrix or fluid properties on a scale much smaller than the wavelength but much larger than individual pore size is known as mesoscopic flow. Pore-scale WIFF is known as local or squirt flow. WIFF caused by pressure relaxation between peaks and troughs of a passing wave in a porous rock, occurs due to density differences between solid matrix and the pore fluid. When the fluid is inviscid, application of the same pressure to the porous material will result in different particle velocities in the solid and fluid, and separate longitudinal waves propagating in the solid matrix and fluid (known as fast and slow waves, respectively) with no dissipation. When the fluid is viscous, the solid and fluid motions are coupled, but there are still fast and slow waves. In the fast wave, the fluid and solid motions are almost in-phase, and in the slow wave, out-of-phase. Thus the attenuation is vast in the slow wave and relatively small in the fast wave – but non-zero due to some small lag of the fluid relative to the solid. To visualise this phenomenon, consider a solid pipe filled with a viscous fluid and being shaken back and force in the axial direction. Were the fluid inviscid, it would have remained stationary. But if the fluid is very viscous, it will be dragged along by viscous forces, but will Boris Gurevich Education matters 36 PREVIEW JUNE 2019