ISSN 1004-4140
    CN 11-3017/P

    地震计方位角偏差校正方法对剪切波分裂结果的影响

    Influence of Seismometer Orientation Misalignment Correction Methods on Shear Wave Splitting Analysis

    • 摘要: 地震计方位角偏差会显著影响剪切波分裂结果的准确性,但不同校正方法的可靠性仍需系统验证。本文以帕米尔高原8H.EP02台站记录的2016年9月1日新西兰北岛东海岸远海的MW7.0级地震事件为例,采用五种方法进行地震计方位角偏差校正:全局最小切向能量法、多事件P波偏振分析法、单记录P波主成分分析法、Rayleigh面波相关系数法和长周期质点运动法。研究对比了不同方法对剪切波分裂参数(快波偏振方向和时间延迟)的影响。结果表明:五种方法均能有效测定方位角偏差,最大差异不超过4°;不同方法获得的时间延迟结果差异较小,在0.01 s以内;快波偏振方向的差异不超过3°。进一步设置±20°方位角偏差的系统测试表明,全局最小切向能量法和多事件P波偏振分析法效果最优。综合考虑计算精度和效率,建议在实际应用中优先选择多事件P波偏振分析法。

       

      Abstract: Seismometer orientation misalignment significantly affects the accuracy of shear wave splitting measurements; however, the reliability of different correction methods still requires systematic verification. Taking the MW7.0 earthquake that occurred on September 1, 2016, off the east coast of North Island, New Zealand and recorded at station 8H.EP02 in the Pamir Plateau as a case study, five methods were adopted for seismometer orientation misalignment correction: global minimum transverse energy, multi-event P-wave polarization analysis, P-wave principal component analysis, Rayleigh surface wave correlation, and long-period particle motion. This study compares the impacts of different methods on shear wave splitting parameters (fast wave polarization direction and delay time). All five methods effectively determined the seismometer orientation misalignment with maximum differences not exceeding 4°; the differences in time delay results obtained using different methods were small, within 0.01 s; the differences in fast-wave polarization directions did not exceed 3°. Further systematic tests using an orientation misalignment of ±20° revealed that the global minimum transverse energy and multi-event P-wave polarization analyses achieved optimal performance. Considering calculation accuracy and efficiency, the multi-event P-wave polarization analysis method should be prioritized in practical applications. These findings underscore the importance of seismometer misorientation correction in shear wave splitting studies for reliable anisotropy characterization.

       

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