Performance and data coherence analyses of BBVS-60 and CMG-3ESPC seismometers

At present, two kinds of seismometers, BBVS-60 and CMG-3ESPC, are widely used in digital seismic networks of China. There are differences in performance and various indicators for two types of seismometers. This study sets up BBVS-60 and CMG-3ESPC seismometers at the surface station and the cave stations so as to compare observation data at the same point, and further to calculate the coherence function values. The results show that there are good correlation between the vertical components recorded by the two kinds of seismo-meters in the frequency range of 0.02−40 Hz and between the horizontal components in the frequency range of 0.04−40 Hz in the observation environment of the comparative station, and the correlativity of the recorded data in the high-frequency （10−40 Hz） and long-period frequency band （10−50 s） is greatly affected by the environmental factors. In addition, the correlativity of the data recorded by the two seismometers has a lot to do with the strength of the input vibration in operating frequency range. The results can provide reference for equipment selection, seismic phase analysis and seismic engineering research.