2018 George P. Woollard Award

Presented to Greg Hirth

Citation by Donald Forsyth

It is a pleasure to introduce Greg Hirth as the George P. Woollard award winner for 2018. Greg is a superb experimentalist in the field of rock deformation and, more than anyone else, has helped to translate knowledge of rheology into models of tectonic processes, providing the needed rigor for development of more realistic models. Greg has had enormous influence on the field, with 26 papers having been cited more than 100 times apiece. His classic 1996 paper with Kohlstedt on the role of water in the mantle has been cited more than 1100 times. He has also explored the effect of melt in the mantle on the rheology of the aggregate, the effects of grain size evolution on strain localization and mantle seismic velocities, and the mechanisms for melt migration.  In collaboration with others, he has applied his deep knowledge of rheological processes to models of the evolution of the oceanic lithosphere, the origin of trench parallel anisotropy in the mantle wedge in subduction zones, the dynamics of subducting slabs, electrical resistivity in the oceanic lithosphere and asthenosphere and beneath Archaen cratons, the origin of intermediate depth earthquakes, the structure of the Iceland plume, and the role of grain-size related strain localization in the development of fault zones and mylonites. He is very frequently invited to workshops on various tectonic processes to be the “rheology expert”. Greg’s unique talent is his ability to communicate across many disciplines, offering important insights that lead to fundamental progress in each. Actually, he has many unique talents, as I discovered on a field trip with him when he gave a superb imitation of a screech owl’s call. In short, Greg is a perfect candidate for the Woollard award and it is my pleasure to be his friend and colleague.