OSG-057 Superconducting Gravimeter Noise Levels in Lhasa (China)

This research tests OSG-057 superconducting gravimeter (SG) performance in Lhasa in terms of noise levels in the seismic (2 min to 1 h), sub-seismic (1 to 6 h), and tidal (above 6 h) bands. Based on the Seismic Noise Magnitude (SNM) and Sub-Seismic Noise Magnitude (SSNM), 0.867 and 2.608 respectively, and compared to the noise levels of other SGs in the Global Geodynamics Project (GGP)/International Geodynamics and Earth Tide Service (IGETS), it is concluded that the instrument-site combination in Lhasa has low noise and good quality in both the seismic and sub-seismic bands. The seismic and sub-seismic band results were confirmed by large signal-to-noise ratio amplitude spectra observations below 1 milliHertz (mHz) obtained from OSG-057 data record residuals after the 4/11/2012 M8.6 Sumatra earthquake, and by background free Earth oscillation observations (‘hum’), although very weak. Using the ETERNA Earth Tide Analysis program in the tidal band, it was found that the OSG-057 performs well due to the low average noise amplitudes and small standard deviations. Knowledge of the noise levels of the OSG-057 SG in Lhasa in different frequency bands provides a necessary precondition and reference for its applications to both global and regional geodynamical researches