Tilt susceptibility of the scintrex CG-5 autograv gravity meter revisited

Abstract

In 2014 a team of researchers from five European universities reported on a high tilt susceptibility of the Scintrex CG-5 Autograv land gravity meter. In a series of experiments they demonstrated that the instrument provides incorrect readings after being tilted by angles of at least about 6∘ for a period of at least a few minutes. The readings may be offset by tens of μGal, and it may take hours before the first reliable readings can be taken. They recommend to keep the instrument in upright position within less than the critical angle of about 6∘ during transits, which may be unrealistic during field operations in hilly terrain, during car transportation or when walking with the instrument in a backpack. The instruments tested in 2014 were purchased between 2003 and 2011. Here, we report about the results of a series of experiments with the latest release of the Scintrex CG-5 purchased in 2015 using the same experimental set-up as in 2014. We show that the instrument is still susceptible to tilting though the initial offset has been reduced by about 50%. However, readings may still be offset by tens of μGal if the tilt exceeds about 6∘ and lasts for more than 1 min. Moreover, the time it takes the instrument to provide reliable readings in line with the specifications may still take several hours depending on the temporal duration of instrument tilting. From this we conclude that the problem of tilt susceptibility has not been solved yet.