Ambient noise level of North China from temporary seismic array

Using vertical component continuous waveform data observed by North China temporary seismic array, we analyzed the seismic ambient noise characteristics inNorth Chinaby calculating the power spectrum density and corresponding probability density function. The results show that high-frequency (above 2 Hz) ambient noise levels in the eastern plain and sedimentary basin region are similar to the global new high noise model (NHNM), the average noise levels at 3mdash;18 s periods are lower than the average values between NHNM and new low noise model (NLNM); high-frequency noise levels in the mountain and western highland region are significantly lower than NHNM, and most of the average noise levels at 1mdash;18 s periods are significantly lower than the average value between NHNM and NLNM; the noise levels with periods over 18 s in different regions show small difference. There is a clear diurnal ambient noise variation in some observations of the temporary seismic array; the noise levels at a few stations are significantly higher than at surrounding stations, implying human activity interference. The noise levels at different stations reveal that high- and low-frequency noise levels can be reduced to some extent by placing the sensor in a vault. The analysis results of station ambient noise characteristics can provide an important basis for quantitative assessment of the seismic array data quality, station optimization and adjustment during observation.