Modelling hysteresis effect in Scintrex CG-3M gravity readings
M. Repanic and M. Kuhar
Journal name: Geophysical Prospecting
Issue: Vol 66, No 1, January 2018 pp. 257 - 269
Info: Article, PDF ( 3.89Mb )
Significant hysteresis effects after transport in the upright position are found during measurement for the purpose of calibration of Scintrex CG-3M gravimeters serial numbers 4372 and 4373. The effects amount to 0.60 and 0.15 μms−2 during the first 10 minutes and an additional 0.35 and 0.10 μms−2 during the next 10 minutes after transport for gravimeters 4372 and 4373, respectively. Such significant and not completely homogenous effects do not completely cancel out when forming gravity differences. An iterative MATLAB algorithm has been developed that models hysteresis effects using exponential functions that account for shifts in time and eliminates the hysteresis effects from the measurements. The method facilitates determination of an exponential function of hysteresis from multiple observation series with different unknown offsets and significant noise that prevents the application of conventional methods. Hysteresis elimination from measurements for the purpose of calibration resulted in (mostly significant) increases in the precision of adjusted calibration constants for both gravimeters. It is shown that, in order to obtain reasonable results, modelling the hysteresis effects should be based on approximately 30 minutes of readings. Finally, one can conclude that hysteresis effects surely do build up during transport, contrary to statements by Scintrex.