Deepwell monitoring of strain-sensitive parameters over the greater Southern California uplift

Several wells and springs near active faults in southern California have been monitored for the concentration of Rn, Na⁺ , K⁺ , Mg⁺² , and Cl^- for periods of up to 24 months, in an effort to see if any of these constituents show variations which may be related to seismic activity. Radon might reflect either a change in the rock surface area to pore volume ratio or a change in groundwater flow characteristics. The chemistry may change with a change in the flow characteristics. Only a few of these sites have shown significant fluctuations in either radon or chemistry. Data from cold springs are consistent with a model in which ionic constituents are controlled by reactions in the soil zone and radon concentrations are controlled by flow rates in the aquifer.