Professor George Walker

Creative and influential volcanologist

George Walker was one of the most creative, productive and influential British volcanologists of the 20th century.

George Patrick Leonard Walker, volcanologist: born London 2 March 1926; Assistant Lecturer, then Lecturer, Imperial College, London 1951-64, Reader in Geology 1964-79; FRS 1975; Captain J. Cook Research Fellow, Royal Society of New Zealand 1978-80; G.A. Macdonald Professor of Volcanology, University of Hawaii 1981-96, Professor Emeritus 1999-2005; married 1958 Hazel Smith (one son, one daughter); died Gloucester 17 January 2005.

George Walker was one of the most creative, productive and influential British volcanologists of the 20th century.

In general, his fame rested on his ability to meld observational skills with novel conceptual models to yield fundamentally new insights into how volcanoes worked. He covered a wide range of volcano types and eruption styles, from lava flows on Hawaii and Mount Etna through to huge pumice eruptions in the Azores, Italy and New Zealand. His overall research contribution arose from his dedication to measuring, rather than simply describing, eruptions and their deposits and using his exceptionally keen intuition to generate major advances in understanding.

His work was characterised by its originality and broad scope, and forms the underpinning of most modern understanding of how volcanoes work. He, more than any other individual worldwide, played a role in turning volcanology from its previous descriptive style into a modern quantitative science.

He was born in 1926 and brought up in London and Northern Ireland. As a teenager he decided that he knew nothing about botany or geology, so he bought a book on each subject and became rapidly captivated by the latter. He subsequently studied geology for his bachelor's and master's degrees at Queen's University, Belfast and then moved to Leeds University to complete a PhD in 1956.

He was appointed to a lectureship at Imperial College, London, in 1954 where he developed outstanding skills as a mineralogist, specialising in studies of the zeolite minerals that had developed in ancient sequences of basalt lavas. Walker's research contributions covered many areas of volcanology through the years.

His first major contributions arose from his recognition that different combinations of the many zeolite species (about 60 of which he was able to recognise casually in the field) were consistently present in specific layers of rock and thus showed how far below the original ground surface any particular piece of lava had been buried. He initially used these simple observations in studies of volcanic rocks in Antrim and the Inner Hebrides to reconstruct the shape of ancient volcanoes of which, for example, the islands of Mull and Skye are the eroded remnants.

More notably, he then in eastern Iceland mapped huge areas of otherwise monotonous basalt lava sequences and used the patterns of zeolite zonation to make fundamental inferences about the structure of the upper parts of the Earth's crust there. These observations, gathered over months of painstaking fieldwork, were critical in providing geological evidence for the process of sea-floor spreading during the development of the revolutionary ideas in Earth sciences that have since become known as plate tectonics.

However, in 1963-64 the eruption of Surtsey occurred off the south coast of Iceland, and a visit to see a live volcano captured Walker's interest to the extent that he changed research directions from old, cold rocks into the products of young volcanism. From the mid-1960s through to the 1980s, his research efforts were focused on young volcanic eruptions and their products.

Walker's work on young volcanoes was firstly carried out at Imperial College, where he rose to the rank of Reader, but in 1978 he left to take up a Captain James Cook Research Fellowship of the Royal Society of New Zealand, based at the University of Auckland. In New Zealand he (along with considerable assistance from his wife, Hazel) threw himself into full-time research on eruptions from New Zealand's young caldera volcanoes of Taupo and Okataina, contributing many new and fundamental insights into eruptions at large rhyolitic volcanoes. He then in 1981 moved to the University of Hawaii and took up the newly established Gordon Macdonald Chair in Volcanology in which position he continued until his retirement in 1996.

In Hawaii he continued his innovative research, concentrating (as was only appropriate) mostly on the structure of basaltic volcanoes and dynamics of basalt lava flows. On his retirement he returned to the UK to live in Gloucester, but continued working in the field and as an Honorary Professor at Bristol University on various aspects of volcanology.

George Walker's achievements in research were widely recognised by elections as a Fellow of the Royal Society of London in 1975 and as an Honorary Fellow of the Royal Society of New Zealand in 1987. He also received an Honorary Doctorate from the University of Iceland, the Thorarinsson Medal (the highest award in volcanology) from the International Association of Volcanology and Chemistry of the Earth's Interior and the Wollaston Medal, the highest award of the Geological Society of London. In 1977, for his contributions to Icelandic geology, Walker was awarded the Icelandic Order of the Falcon, conferred by the President of Iceland.

As well as his exceptional contributions to research, Walker was a brilliant teacher, supportive of anyone who wished to learn, at all levels from schoolchildren to postgraduate students. He taught in a deceptive style, getting across complex ideas and new concepts with simple diagrams and clear exposition. In the field he was utterly in his element while there was still light in the sky, and he had an unequalled ability in showing students how to understand complex volcanic processes using simple systematic observations allied with logical deductive thinking.

Walker's success as a scientist owed much to the support given to him for over 40 years by his wife Hazel, who not only raised their children, Alison and Leonard, but typed and retyped manuscripts (in the days before word processors) and did large amounts of laboratory work for him.

Colin Wilson