Fig. 8From: Cross-validation of independent ultra-low-frequency magnetic recording systems for active fault studiesDay-long time series for April 12, 2014, recorded in a voltage and b nanotesla (i.e., after correction for instrument response). All data are from the north–south coils and are shown after a 1000-s high-pass filter. The time series are all zero-mean but are plotted with an offset for easier visual comparisonBack to article page