Christopher H. Scholz, David L. Goldsby, Yves Bernabé, and Brian Evans | EOS
Tuesday, March 6, 2018
Long time member of EAPS, and close collaborator with William F. Brace, Walsh used rigorous mechanical principles to devise theories fundamental to such diverse fields as seismology, oil and gas exploration, and hydrology.
Joseph B. “Joe” Walsh died on 30 August 2017 at the age of 86 in Adamsville, R.I., where he had lived for many years. Joe was well known in the rock mechanics community, although perhaps underappreciated outside it. The influence of his work is, nonetheless, broad and profound.
Seismologists who interpret high velocities of compressional waves compared with those of shear waves (high Vp/Vs ratios) as indicators of high pore pressures, oil explorers who recognize oil and gas zones in tomographic images, and geophysicists identifying high permeability and water content from electrical conductivity measurements all rely on Joe’s foundational work. The reason is because these scientists are not so much measuring the properties of the rock as measuring the influence of its cracks. Joe, in a series of classic papers in the 1960s and 1970s, did the fundamental work establishing the profound effect of cracks on the elastic and transport properties of rock.
By recognizing this influence, Joe was able to provide, for example, rational explanations for relationships between the constitutive relations for permeability and for electrical resistivity, to predict how increasing effective pressure changes permeability, and to understand the influence of surface roughness on joint transmissivity or the coefficient of friction. Whole fields of study are based on those beginnings.
Joseph B. Walsh was born in Utica, N.Y., the son of Joseph B. and Ann (née Bowman) Walsh. He grew up in upstate New York before moving to Massachusetts to attend the Massachusetts Institute of Technology (MIT), from which between 1952 and 1958 he received bachelor’s, master’s, and doctor of science degrees in mechanical engineering.
His D.Sc. work yielded a paper with Frank McClintock in which they developed what became known as the modified Griffith theory for brittle fracture in compression. After graduating from MIT, Joe spent 2 years in industry, including a stint with a consulting company in Stockholm. This job morphed into a globe-circling trip in a VW bug, ending with Joe in California, substantially poorer financially but much richer in experience.
Returning to Massachusetts, he applied his skills in solid mechanics as an engineer at the Woods Hole Oceanographic Institution, where he was responsible for the design of the pressure hull for the pioneering submersible Alvin.
Joe joined the Geology and Geophysics (later Earth, Atmospheric and Planetary Sciences) Department at MIT in 1963, beginning a 25-year collaboration with W. F. Brace. It was a very fruitful combination: Joe did the theory, and Bill did the experiments. The Walsh-Brace period was one of rapid development in rock mechanics on many fronts. A host of graduate students and postdocs (including most of us) were trained under their guidance, many of whom went on to productive research careers in academia and industry.
Theory Grounded in Reality
Joe’s papers are both succinct and eloquent. He identified the most pertinent elements of each problem and focused his analysis exclusively on those aspects. His chosen tools were pencil, paper, and the fundamental principles of mechanics.
Joe arrived at work each day impeccably attired in coat, tie, and slacks. Sitting at his desk, he would dive into his cool mathematical treatments, seemingly abstract but always securely attached to reality. As a result of his training with McClintock, Argon, and others in MIT’s Mechanical Engineering Department, Joe always tested his work with experimental or observational data, thus providing a perfect interface with Brace’s group.
A Taste for Conversation and Rugby
Despite his analytical proclivity, Joe was not detached socially. To all who knew him, he was a quiet, unassuming man with a wry sense of humor. He liked people and had catholic tastes in his choice of company. At lunchtime, he could be found at a local diner, talking to machinists, custodians, or academics. In the evening, he might dine at one of several classic private social clubs in the Back Bay.
His gentle demeanor gave no clue that in his younger years he was an avid rugby player and the founding director of the U.S. Rugby Foundation. Joe was equally at ease bantering with a surly waitress or securing a large donation for the rugby foundation from an influential industrial magnate.
A Very Active Retirement
Joe retired from MIT in 1986 and settled in Rhode Island. In “retirement,” Joe continued to conduct theoretical studies of fluid flow in fractured rocks and of rock friction. He was appointed visiting scholar in the Department of Earth, Environmental and Planetary Sciences at Brown University in 1999, and he continued in that capacity until his passing, having been reappointed only a few months before.
Joe eagerly mined experimental rock friction data at Brown, which he used as a starting point for his analyses. Armed with his famous and formidable yellow legal pad and No. 2 pencil, Joe worked closely with experimentalists at Brown and elsewhere to establish a physical basis for rate and state friction laws.
In addition to scientific interactions, Joe also educated younger scientists at Brown by his example about the importance of a proper lunch, the joys of poetry (Joe could, and did, recite many poems from memory), and the meaning of savoir faire. Joe continued his scientific work up to the time of his death.
Joe’s work often took him overseas: He served as a visiting scientist at the University of Cambridge in England; the University of Edinburgh, Scotland; and the South African Chamber of Mines in Johannesburg.
Although his name is not a household word outside the rock mechanics community, Joe has been well recognized for his accomplishments. In 2007, he received the Rock Mechanics Research Award, in 2000 he was honored as a Life Fellow at the University of Cambridge, and in 1993 he was named a Fellow by the American Geophysical Union.
—Christopher H. Scholz (email: firstname.lastname@example.org), Lamont-Doherty Earth Observatory, Columbia University, Palisades, N.Y.; David L. Goldsby, Department of Earth and Environmental Science, University of Pennsylvania, Philadelphia; and Yves Bernabé and Brian Evans, Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge