Noise analysis of the observatory superconducting gravimeter in the normal mode frequency range using gravity data of Ghuttu, Garhwal Himalaya, India

We present a study on gravity data from the Observatory Superconducting Gravimeter (OSG-051) located at MPGO Ghuttu in the Garhwal Himalaya, India. Ambient noise observed at this site is compared with other worldwide SGs and computed seismic noise magnitude for the OSG-051. Instrumental noise has been observed at frequencies ranging from ∼0.0239 to ∼0.03207 Hz in the form of parasitic mode for the lower and upper sensors of SG, whose quality factor has been estimated in different modes of oscillations. The signal is enhanced at noise reduction below 2.0 mHz using local barometric pressure data and modelled tidal effect of the site. Other seismic noise factors are discussed through data analysis of OSG-051. OSG-051 and trillium 240 Broad Band Seismometer data are analysed and compared in the seismic normal mode frequency band. Several observations have been made regarding noise sources that affect the gravity data in the seismic normal mode’s frequency band. Residual gravity data after removal of atmospheric pressure, tidal, and co-seismic effects, respond very well to long-period seismometers than any conventional seismometer. This characteristic and low noise level of the MPGO Ghuttu site makes it a suitable station for long-period seismometer studies.