Research on Taiyuan gPhone Gravimeter Background Noise Level of CMONOC
1 National Earthquake Infrastructure Service, 63 Fuxing Road,Beijing 100045,China
2 Key Laboratory of Earthquake Geodesy, Institute of Seismology, CEA, 40 Hongshance Road,Wuhan 430071, China
Abstract The background noise level in seismic frequency band (200~600 s), sub-seismic frequency band (1-6 h) and tide frequency band (period>6 h), based on one year continuous observation of gPhone gravimeter at Taiyuan station of the crustal movement observation network of China (CMONOC), are investigated using a numerical analysis method, and they are compared with the noise level of other superconducting gravimeters (SG). It is found that the seismic noise magnitude (SNM), sub-seismic noise magnitude (SSNM) and tidal noise magnitude (TNM) of the gPhone gravimeter are 3.641, 4.659 and 5.359 respectively. The SNM and SSNM of the gPhone gravimeter are higher than that of SG, but when the frequency is below 0.8×10-4 Hz, the noise level of the gPhone gravimeter is lower than the new low noise level (NLNM). The Earth’s free oscillations excited by Chile Mw8.1 in 2014 are analyzed, and it is found that although the noise level of the gPhone gravimeter is higher than that of SG, the signal of oscillations can still be observed clearly. This means that the gPhone gravimeter is not only suited for researching tidal and sub-seismic modes, it also can be used for obtaining free oscillations signal in seismic frequency band.
