2020年7月，西藏自治区仲巴地震台台基观测方式由地下深坑摆墩观测改造为地表观测，改造后垂直向高度提升近2.3 m，其他条件保持不变，计算台基改造前后不同时间段的噪声功率谱密度PSD及相应概率密度函数PDF，并以未进行台基改造的八宿地震台为参考台站（两台站观测房布局及相关设施条件基本相同），计算并对比分析2019—2021年两台PSD及相应PDF值，以评估观测方式改变对仲巴地震台台基背景噪声的影响。结果显示，摆墩改造后，仲巴地震台月、日噪声水平在2—50 Hz（周期0.02—0.5 s）高频段区间明显升高，表明人为活动、车辆行驶等产生的噪声明显加大，地震计更易接收台站周边人为噪声信号，台基质量显著下降。因此，在进行地震台站建设、改造施工时，应慎重改变台基观测方式。
In July 2020, the observation method of the station base of the Zhongba Seismic Station in Xizang Autonomous Region was transformed from the underground pit pier to the surface observation. After the transformation, the vertical height was increased by nearly 2.3 m. Other conditions remained unchanged. The noise power spectral density PSD and corresponding probability density function PDF were calculated at different times before and after the transformation of the station base. The Basu Seismic Station that has not undergone base transformation is used as the reference station (the layout of the observation room and related facilities of the two stations are basically the same). The PSDs and corresponding PDF values of the two stations in 2019-2021 are calculated to evaluate the impact of observation method changes on the background noise of the Zhongba Seismic Station base. The results show that after the pier renovation, the monthly and daily noise level of the station base of the Zhongba seismic station increased significantly in the high-frequency band range of 2-50 Hz (period 0.02-0.5 s), indicating that the noise generated by human activities and vehicle driving has increased significantly. Seismometers are more likely to record artificial noise signals around the station, and the quality of the base is significantly reduced. Therefore, when building and renovating seismic stations, the observation method of the base should be carefully changed.
2025,46(1): 64-70 收稿日期：2024-11-5
DOI：10.3969/j.issn.1003-3246.2025.01.009
基金项目：西藏自治区地震局自设科研项目（项目编号：XDZ-202401005）
作者简介：白玛桑布（1993—），男，藏族，西藏日喀则市亚东县人，本科学历，工程师，主要从事测震学、地震台站站网运维等相关工作。E-mail：1726513704@qq.com
参考文献：
白玛桑布，单增曲珠，次旦卓玛，等. 观测环境变化对日喀则地震台观测质量的影响[J]. 地震地磁观测与研究，2024，45（5）：67-73.
葛洪魁，陈海潮，欧阳飚，等. 流动地震观测背景噪声的台基响应[J]. 地球物理学报，2013，56（3）：857-868.
吴丽慧，廖武林，黎金玲，等. 新冠疫情防控前后湖北恩施地震台背景噪声变化分析[J]. 地震工程学报，2022，44（1）：145-151.
杨亚运，傅卓，马伟. 地震计墩改造对观测数据影响分析[J]. 高原地震，2021，33（2）：44-50.
McNamara D E, Buland R P. Ambient noise levels in the continental United States[J]. Bull Seismol Soc Am, 94(4): 1 517-1 527.
