Fig. 14From: Cross-validation of independent ultra-low-frequency magnetic recording systems for active fault studiesStandard deviations of amplitudes for each hour of data calculated individually for each sensor: a north-oriented magnetometers; b east-oriented sensors; and c vertical sensors, at Jasper Ridge and Fresno, for April 5, 2014 to May 12, 2014. Fresno data are not available for April 29, 2014 to May 1, 2014. d Geomagnetic activity index Ap for the same time periodBack to article page