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新近建成的中国地震台阵(CEArray)由中国国家数字地震台网(CNDSN)、31个区域地震台网以及几个小孔径台阵构成,台站总数逾千,其中宽频带台站850多个。这一巨大台阵的建成为日常的地震活动监测及窥探地球内部结构提供了前所未有的契机。许多现代地震学研究都要进行垂向和水平分量的旋转,用以分离不同类型的地震波。因此两个水平分量的方位信息构成了正确旋转的关键。我们分析了CEArray台阵记录到的远场P波质点运动,并用以估测每个台站的BHN分量方位角。我们提出了一种基于信噪比的多事件方法来获取最佳方位角,可以很好地解释台站记录的P波质点运动特征。该方法可以给出方位角的稳健估值,包括基于背景噪声水平的误差。我们发现近1/3台站存在不同程度的方位角相关问题,包括水平分量方位角偏差、分量命名错误、以及单个或多个分量的极性反转等。这些问题在基于旋转的地震学分析中必须要慎重考虑。
The newly completed China Earthquake Array (CEArray) consists of China National Digital Seismograph Network (CNDSN), 31 regional seismograph networks and several small aperture arrays. The total number of stations is over 1,000, of which over 850 are broadband stations . The completion of this huge array provides an unprecedented opportunity to monitor and inspect the earth’s internal structure for daily seismic activities. Many modern seismological studies require the rotation of vertical and horizontal components to separate different types of seismic waves. Therefore, the azimuth information of the two horizontal components constitutes the key to correct rotation. We analyzed the far-field P-wave particle motion recorded by the CEArray array and used to estimate the azimuth of the BHN component at each station. We propose a multi-event method based on signal to noise ratio to obtain the best azimuth, which can well explain the movement features of P-wave particles recorded by the stations. This method can give a robust estimate of azimuth, including errors based on the background noise level. We found that nearly one-third of stations have different degrees of azimuth-related problems, including azimuthal deviation of horizontal components, component naming errors, and polarity reversal of single or multiple components. These problems must be carefully considered in seismological analysis based on rotation.