RADON ENHANCEMENTS IN THE EARTH - EVIDENCE FOR INTERMITTENT UPFLOWS

222Rn measurements at 60cm in the earth show background patterns that can be remarkably reproducible over time. At a site in New Mexico the readings taken at monthly intervals over a 13‐month period for a set of 55 positions give different, but nearly constant monthly readings at each position, the typical standard deviation being 22%. Superimposed on that stable pattern have been three periods during which spatially grouped radon readings, increased by a factor of 2 or more over their normal values. The simplest description of the source of the increases is sporadic puffs of upflowing gas, originating at as yet unknown depths. Alternative, less likely interpretations are considered. Separate periods of mostly low radon values may be due to downflow of gas. Copyright 1979 by the American Geophysical Union.