Analysis of Seismic Ambient Noise Characteristics in Fujian Region

WU Lihua; ZHANG Baojian; HUANG Heling; DAI Lijin; ZHAO Wenbo

doi:10.13512/j.hndz.2026.01.02

Abstract：To enhance the understanding of ambient noise characteristics in Fujian region and the quality of obser-vation data of Fujian Earthquake Early Warning Network,the continuous waveform data of 120 seismic stations in Fujian Earthquake Early Warning Network in 2023 were selected,and the seismic noise level and background noise characteristics in Fujian region were evaluated by using the analysis methods of seismic noise power spectral density(PSD),probability density function(PDF)and root mean square(RMS).The results show that the overall noise level of Earthquake Early Warning Network is mainly level Ⅱ,and the spatial distribution shows a certain re-gional pattern.The noise level of stations in coastal areas with dense population and frequent industrial activities is higher than that of stations in central and western mountainous areas.The analysis of noise spectrum characteristics shows that the noise in the low frequency band(<0.1 Hz)is mainly affected by temperature and humidity distur-bance and airflow,and the noise PSD value fluctuates between-170 dB and-130 dB.The noise of the horizontal channel of some stations is significantly higher than that of the vertical channel.It is suggested to strengthen the pro-tection measures of seismometers and the calibration of datum plane.The mid-frequency(0.1-1 Hz)noise is closely related to marine activities,with a PSD value about 20 dB higher than the global lowest noise model(NLNM).The dominant frequency(0.3 Hz)is 0.1 Hz offset from the global lowest noise model,and the dual-frequency microseis-mic energy in winter is slightly higher than that in summer.The high-frequency(>1 Hz)noise is dominated by hu-man noise,with significant diurnal variations.Installing away from densely populated towns or cave installation can effectively reduce interference sources around the station.