Don Russell

My research interests centre around the application of methods of physics to the solution of problems of interest to geophysics. These interests have brought me into contact with research in geochronology, mass spectrometry, geomagnetism, seismology, gravimetry and seismoelectric phenomena.

My colleagues, at the University of Toronto and at UBC, and I were the first to demonstrate the existence of very ancient rocks in Australia, and to show that some rocks in Great Britain were much older than previously supposed. We directed much of our attention to the measurement and interpretation of the isotopic ratios of lead in lead ores. We were the first to demonstrate clearly the linear arrays of isotopic data that are now known as secondary isochrons. With Steve Pearce, I demonstrated the inversion of cosmic-ray produced nuclei in iron meteorites to obtain exposure ages that allow for the possibility that the incident flux has not been constant in time.

The physics of geophysical instruments, a matter that has always interested me, has now become my principal research interest. Since our first serious work on fluxgate magnetometers in 1982, we have achieved a new understanding of the fluxgate theory. With colleagues Barry Narod, Zu-Cheng Gao and Frank Kollar, I have published papers using the method of Floquet to solve the appropriate differential equations, and matrix techniques to develop phase-plane solutions. Narod has incorporated a geophysical company, which is building magnetometers under license from The University of British Columbia. His instruments have found wide application in terrestrial geophysics and have been flown in space vehicles.

Our current research is based on reports, principally in the Soviet literature, that the conversion of acoustic to electromagnetic signals in quartz, sulphides, kimberlites and possibly other minerals, produces signals useful for geophysical exploration. Seismoelectric conversions are produced by any of several mechanisms. My colleagues, Michael Maxwell, Karl Butler and Anton Kepic, and I have observed linear responses due to electrokinetic conversions at Haney, British Columbia, at Humboldt, Victoria, and at South Porcupine, Ontario, and possible piezoelectric conversions from quartz deposits at Humboldt, Victoria, and at South Porcupine, Ontario. We have observed pulsed radio-frequency responses from sulphides at Noranda, Quebec, at Kimberley, British Columbia, and at Myra Falls, British Columbia. It was generally possible to locate the targets using the arrival times of the responses.

There are two reasons why seismoelectric techniques are desirable. Firstly, the utilization of new physical properties opens up the possibility of detecting and locating targets, such as quartz and sphalerite, that can be difficult to observe with current geophysical techniques. Secondly, the seismic input has a substantially smaller wavelength than the effective diffusion wavelength of electromagnetic techniques, resulting in potential for higher resolution. Although our primary interest is application to exploration, the phenomena also have significance for earthquake prediction and rock physics.