Brace was born in Littleton, N.H., and educated in the Boston area, finishing preparatory school in Danvers. He matriculated as an MIT undergraduate in 1943, and, following a tour of duty in the Navy, obtained SB degrees in naval architecture in 1946 and in civil engineering in 1949. In 1953, he earned a PhD from MIT’s Department of Geology and Geophysics.
Perhaps motivated, at least in part, by his love of the outdoors, he completed his dissertation in structural geology, studying the fabric and structure of rocks from the Green Mountain anticlinorium near Rutland, Vt. In that study, Brace remarked that interpretations of the field relations were limited by the lack of reliable mechanical data on natural rocks.
The academic career that followed was a brilliant and successful attempt to fill that intellectual void. Following a postdoctoral fellowship with Francis Birch at Harvard University, Brace established a rock mechanics laboratory in the geology department at MIT. Using an extremely stiff testing apparatus — which Brace designed using principles gained by studying ship design — he investigated the fracture properties of granite, marble and sandstone.
In a watershed study in 1964, Brace demonstrated a causal relationship between shear fracture of rocks and stress-induced micro cracking. Other definitive studies of the dilatancy that occurs during compressive failure have formed a broader basis of understanding of the failure of highly confined materials.
With James Byerlee of Stanford University, Brace realized that the stick-slip friction events observed in the laboratory could be used to understand ruptures occurring at much larger scale during destructive earthquakes. In a long and fruitful collaboration with Joseph Walsh of MIT, Brace used careful experiments, thorough mechanical analyses, and thoughtful observations of microstucture to develop a systematic constitutive description of such physical properties of rocks as acoustic wave velocity, electrical resistivity and permeability.
Brace’s work can be characterized, colleagues said, by its thoroughness and high standards in both experimental technique and underlying understanding of fundamental physics and mechanics. He often designed and developed new testing apparatus, including the stiff press mentioned above and an internally heated servo-controlled mechanical testing device used to study inelastic behavior of crustal rocks at high temperatures. Brace also pioneered new techniques to study permeability in crystalline rocks, electrical properties of water-saturated rocks under high confining pressure, and the detailed microstructure of ruptured materials using argon-etching techniques. Throughout this remarkable body of work, colleagues said, Brace never lost sight of his ultimate goal: applying the results of these studies to natural deformation.
With MIT’s Christopher Goetze and other collaborators, Brace showed that data from mechanical tests could be used to produce a simple, quantitative description of the strength of the Earth’s crust. No one was more aware than Brace of the limits in such a generic description, but Goetze-Brace strength profiles are still used today as starting models in studies of geodynamics and structural geology. Remarkably, Brace’s career started in a succinct statement of an ambitious scientific goal and ended with robust descriptions for a wide variety of physical properties.
Brace’s professional contributions were recognized by election to the National Academy of Sciences and by selection as a fellow of the Geological Society of America, the American Geophysical Society and the American Academy of Arts and Sciences. He was presented with the Bucher Medal of the American Geophysical Union in 1987 and with a Distinguished Achievement Award from the U.S. National Committee on Rock Mechanics in the same year.
From 1976 to 1988, Brace was the Cecil and Ida Green Professor of Geology at MIT; from 1981 to 1988 he served as the head of the Department of Earth, Atmospheric and Planetary Sciences — a department that arose under his leadership from the merging of MIT’s Course XII, Earth and Planetary Sciences, and Course XIX, Meteorology and Physical Oceanography. Brace’s efforts as department head were essential to ensuring a well-balanced and thorough approach in thinking about the Earth and its processes as part of a unified system.
Brace had a deep love for the outdoors, and was an avid hiker, skier, bicyclist and distance runner. He competed in the Boston Marathon and ran up (and down) Pikes Peak and the Grand Canyon. In retirement, he became an accomplished cabinetmaker, combining deep understanding of the mechanical properties of wood with technical joinery and profound artistry.
Brace is survived by his wife, Margaret; sons, Nathaniel and Colin' daughter, Sarah; and several grandchildren. A memorial service will be held June 12 at 11 a.m. at the Unitarian Church in Concord, Mass., where he was a resident.