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作者:: 蔡辉腾¹; 2; 陈颙¹; 金星²; 徐嘉隽²; 徐艺鹤³; 李稳⁴; (1.南京大学地球科学与工程学院,江苏南京 210008; 2.福建省地震局,福建福州 350003; 3.中国地震局地球物理研究所,北京 100810; 4.中国地震局地球物理勘探中心,河南郑州 450003)

Author(s):: CAI Huiteng¹; 2; CHEN Yong¹; JIN Xing²; XU Jiajun²; XU Yihe³; LI Wen⁴; (1. School of Earth Sciences and Engineering,Nanjing University,Nanjing 210008,Jiangsu,China)(2. Fujian Earthquake Agency,Fuzhou 350003,Fujian,China)(3. Institute of Geophysics,China Earthquake Administration,Beijing 100810,China)(4. Geophysical Exploration Center,China Earthquake Administration,Zhengzhou 450003,Henan,China)

Keywords:: Fujian region; ambient noise; power spectral density; probability density function; temporal-spatial characteristics

摘要:: 为进一步加强对福建地区噪声特性的认识以及提升台站地震观测质量,计算了2014年福建地震台网宽频带地震仪连续观测数据的功率谱概率密度函数,并分析其影响因素和不同频段时空变化特性。结果表明:人文噪声平均水平最高地区位于福建沿海福州至厦门一带,07:00—18:00的功率谱密度要明显高于其它时间段,12:00左右出现间歇性低谷期,夜间有不同程度的降低,日变化除了在春节假期大幅下降外,均处于较为稳定态势; 福建地区次级微震主要成分是Rayleigh波,主频约为2.7 s,主微震主频约为16 s,次级微震平均水平最高地区也位于沿海一带,向内陆方向呈衰减趋势,其日变化明显,与台风和潮高有较高的相关性。

Abstract:: In order to enhance the understandings of characteristics of seismic noise and improve observation qualities of fixed or mobile seismic stations in Fujian region,we use continuous waveforms of broadband seismograph in Fujian region in 2014 to calculate the power spectral probability density function(PDF),and discuss the influencing factors and space-time features of PDF in different frequencies. The results show that,the areas with the highest human activity related noise are located in Fuzhou-Xiamen area along the coast of Fujian province. The power spectral density at 07:00—18:00 is obviously higher than other times,and an intermittent trough shows at around 12:00 and decreases to different extent during night time. Except a sharp drop during the Spring Festival holidays,the diurnal variation was quite stable. The main component of the secondary microtremors in Fujian region is Rayleigh wave with a dominant frequency of about 2.7 s,while the dominant frequency of the primary microtremors is about 16 s. The highest level of the secondary microtremors mean level is also located in the coastal area,and tends to decay inland. There is an obvious diurnal variation for the secondary microtremors and it is highly correlated with typhoon and tidal height.