Deformation and geochemical anomalies near South Sister, Oregon

(Top) 1996–2000 interferogram draped over a 30-m DEM and showing uplift centered a few kilometers (miles) west of South Sister volcano. (Bottom) Geochemical data on top of the 1996–2000 interferogram. The columns show chloride (Cl) and sulfate (SO4) concentrations at sampled springs. The lengths of the cyan columns depict Cl concentration (0.6 to 18.6 mg/L versus a regional background of 0.2 to 0.7 mg/L). The lengths of the red columns show SO4/Cl ratios (0.2 to 2.8). Blue lines highlight stream areas with steady or decreasing Cl concentration in a downstream direction. Red lines highlight stream areas within which Cl concentrations increase downstream. The color bar shows a range increase from 0 to 28.3 mm that corresponds to a continuous color change from violet to red.  Figure adapted from Wicks and others (2002).