南京地震台甚宽频地震计观测性能研究OACSTPCD

In order to further study the observation performance of very broadband seismometers,two types of very broadband seismometers(GL-S120 and ITC-120A)at Nanjing Seismic Station were used to carry out comparative experiments.The difference analysis is carried out from the aspects of the waveform records at the station,correlation and ambient noise.The results indicate that ITC-120A is not susceptible to ambient interference,especially in the vertical direction.The correlation between the two seismometers at night is better than that in daytime.The ambient noise analysis by calculating power spectral density(PSD)illustrates that the noise level of GL-S120 in the low frequency band increases significantly with the increase in ambient interference,resulting in the poor effect in recording remote earthquakes of small to medium magnitudes by GL-S120 and difficult identification of seismic phase.The calculation and analysis of self-noise show that the difference in power spectrum curves of the two seismometers is related to their self-noise level.Factors such as detection methods and ambient noise have an impact on the correlation of equipment self-noise tests,thereby affecting the accuracy of seismometer self-noise calculation.