地震研究

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。

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.

引言
1 数据和处理方法
2 福建地区环境噪声特性分析
3 结论

图1 研究区台站分布图<br/>Fig.1 The distribution of stations in the study area

图1 研究区台站分布图
Fig.1 The distribution of stations in the study area

表1 测震台站地震计属性<br/>Tab.1 Seismometer attributes of seismic stations

表1 测震台站地震计属性
Tab.1 Seismometer attributes of seismic stations

图2 2014年1月1日AXCK台站垂直向波形图<br/>Fig.2 Diagram of the vertical waveform recorded by AXCK station on Jan.1,2014

图2 2014年1月1日AXCK台站垂直向波形图
Fig.2 Diagram of the vertical waveform recorded by AXCK station on Jan.1,2014

图3 AXCK台站垂直分量加速度功率谱密度(黑线)及其经1/9倍频程平滑后的结果(紫点)<br/>Fig.3 Acceleration power spectral density(black line) and its smoothing results after 1/9 octave(purple dot) of vertical component of AXCK station

图3 AXCK台站垂直分量加速度功率谱密度(黑线)及其经1/9倍频程平滑后的结果(紫点)
Fig.3 Acceleration power spectral density(black line) and its smoothing results after 1/9 octave(purple dot) of vertical component of AXCK station

图4 AXCK台站4个周期功率谱密度分布直方图<br/>Fig.4 Histogram of power spectral density distribution of AXCK station at four periods

图4 AXCK台站4个周期功率谱密度分布直方图
Fig.4 Histogram of power spectral density distribution of AXCK station at four periods

图5 2014年1月1日AXCK 台站垂直分量526条功率谱概率密度函数<br/>Fig.5 526 PDF of vertical component recorded by AXCK station on Jan.1,2014

图5 2014年1月1日AXCK 台站垂直分量526条功率谱概率密度函数
Fig.5 526 PDF of vertical component recorded by AXCK station on Jan.1,2014

图6 QZH,FACY和LCGT台站时变化(PDF中值统计,每个时间点约360条PSD)<br/>Fig.6 Time variability of QZH,FACY and LCGT stations(PDF median statistics,about 360 PSD per time point)

图6 QZH,FACY和LCGT台站时变化(PDF中值统计,每个时间点约360条PSD)
Fig.6 Time variability of QZH,FACY and LCGT stations(PDF median statistics,about 360 PSD per time point)

图7 2014年QZH和NPDK台站日变化(PDF中值统计,每天约526条PSD)<br/>Fig.7 Daily variability of QZH and NPDK stations in 2014(PDF median statistics,about 526 PSD per day)

图7 2014年QZH和NPDK台站日变化(PDF中值统计,每天约526条PSD)
Fig.7 Daily variability of QZH and NPDK stations in 2014(PDF median statistics,about 526 PSD per day)

图8 2014年QZH台日变化与潮汐的关系<br/>Fig.8 Relationship between diurnal variation of QZH stations and tides in 2014

图8 2014年QZH台日变化与潮汐的关系
Fig.8 Relationship between diurnal variation of QZH stations and tides in 2014

图9 福建地区背景噪声0.4 s年平均值高于NLNM值的PSD分布图<br/>Fig.9 PSD distribution of the annual average 0.4 s background noise is higher than the NLNM in Fujian area

图9 福建地区背景噪声0.4 s年平均值高于NLNM值的PSD分布图
Fig.9 PSD distribution of the annual average 0.4 s background noise is higher than the NLNM in Fujian area

图10 福建地区背景噪声2.7 s年平均值高于NLNM值的PSD分布图<br/>Fig.10 PSD distribution of the annual average 2.7 s background noise is higher than the NLNM in Fujian area

图10 福建地区背景噪声2.7 s年平均值高于NLNM值的PSD分布图
Fig.10 PSD distribution of the annual average 2.7 s background noise is higher than the NLNM in Fujian area

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备注

引言

1 数据和处理方法

2 福建地区环境噪声特性分析

3 结论

期刊信息