2020 George P. Woollard Award

Presented to Donald Argus

Citation by Richard G. Gordon, Rice University

Donald Argus has made many forefront contributions to active tectonics. He determined the first relative plate angular velocity from space geodetic data. The agreement of his Pacific-North America angular velocity with NUVEL-1 (to which he was a vital contributor) was remarkable and demonstrated the steadiness of plate motion over decades compared with that over millions of years.

Don has also made major advances in understanding the widely distributed deformation of the western U.S. He was the first to determine space geodetically the motion of the Sierra microplate relative to North America, thus settling longstanding debates about the rate and orientation of contemporary deformation in the Basin and Range Province. He also determined the motion of the Sierra microplate relative to the Pacific plate and thus determined the first useful estimates of the convergent displacement rates that cause the California Coast Range to grow today, as well as placing dramatically improved bounds on contemporary strike-slip across the San Andreas Fault system from the Transverse Ranges to Cape Mendocino. He found that the rates of convergence building the Coast Range were typically a few millimeters per year, much lower than rates proposed by others. He related shortening recorded in topography and geologic structures along the Coast Range to the contemporary rates. He furthermore showed why there is a gap in the Coast Range at the latitude of San Pablo Bay—it uniquely undergoes San-Andreas-Fault-System-perpendicular divergence rather than convergence. Thus, he provided a tectonic explanation for why the Sierra Nevada-Great Valley watershed drains to the Pacific there and not elsewhere.

Don has also been a pioneer, with Dick Peltier, in using space geodesy to estimate rates of ice retreat and post-glacial rebound. More recently he has used space geodesy as a high-resolution tool for evaluating water resources and geohydrology.