The self-noise level of a seismometer can determine the performance of the seismic instrument and limit the ability to use seismic data to solve geoscience problems. Accurately measuring and simultaneously comparing the self-noise models from different types of seismometers has long been a challenging task due to the constraints of observation conditions. In this paper, the self-noise power spectral density (PSD) values of nine types of seismometers are calculated using four months of continuous seismic waveforms from Malingshan seismic station, China, and nine self-noise models are obtained based on the probability density function (PDF) representation. For the seismometer STS-2.5, the self-noise levels on the horizontal channels (E–W and N–S) are significantly higher than that on the vertical channel (U–D) in the microseism band (0.1 Hz to 1 Hz), which is a computing bias caused by the misalignment between the sensors in the horizontal direction, while the remarkably elevated noise on the horizontal channels at the low frequencies (<0.6 Hz) may originate from the local variation of atmospheric pressure. As for the very broadband seismometers Trillium-Horizon-120 and Trillium-120PA, and the ultra-broadband seismometers Trillium-Horizon-360 and CMG-3T-360, there is a trade-off between the microseism band range and low-frequency range in the PSD curves of the vertical channel. When the level of self-noise in the microseism band is high, the self-noise at low frequencies is relatively low. Although compared with the other very broadband seismometers, the self-noise level of the vertical component of the STS-2.5 is 3 dB to 4 dB lower at frequencies less than 1 Hz, the self-noise level of the STS-2.5 at high frequencies (>2 Hz) is slightly higher than others. From our observations, we conclude that the nine seismometers cannot reach the lowest noise level in all frequency bands within the working range.

不同型号地震计的自噪声水平直接影响了地震观测数据的质量,并进一步限制了利用地震数据解决地球科学问题的能力.长久以来,由于受到观测条件的限制,准确地测量和比较不同型号地震计的自噪声水平颇具挑战.文中利用马陵山地震台 4 个月的连续地震波形,基于概率密度函数的表示方法计算了 7 个型号地震计的自噪声功率谱密度曲线.对于超宽频带地震计 CMG-3T-360,在微震频带(0.1～1 Hz),水平方向的自噪声明显高于垂直方向,这可能是地震计水平方向相对方位未对齐导致的计算偏差;在低频段(＜0.03Hz),水平方向显著偏高的自噪声可能源于大气压的变化.短周期地震计 JS-S02 的自噪声水平在频率为 0.15～7Hz 时低于全球新低噪声模型(NLNM).宽频带地震计 TDV-60B和甚宽频带地震计 TDV-120VB 在垂直方向的自噪声水平基本一致.宽频带地震计 JS-60 和甚宽频带地震计 JS-120 的自噪声水平在微震频段接近或低于 CMG-3T-360.当频率为 0.008～0.08Hz时,JS-120 水平向 NS 通道的自噪声水平高于 CMG-3T-360 功率谱密度 68%的置信区间.