Statistical analysis of ULF seismomagnetic phenomena at Kakioka, Japan, during 2001-2010
Statistical analysis of ULF seismomagnetic phenomena at Kakioka, Japan, during 2001-2010
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DOI：
10.1002/2014ja019789
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发表时间：
2014-06-01
影响因子：
2.8
通讯作者：
Yoshida, Shuji
中科院分区：
文献类型：
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作者：
Han, Peng;Hattori, Katsumi;Yoshida, Shuji
为了澄清和验证超低频（ULF）震磁现象，我们对2001-2010年期间在日本Kakioka（KAK）台站观测到的地磁数据进行了统计研究。利用小波变换分析方法研究了频率在0.01Hz附近的超低频地磁信号的能量。为了减少人为噪声和全球地磁扰动的影响，我们只使用夜间（LT 2：30 A. M.到凌晨四点M.）并利用从一个遥远的观测站，Kanoya，作为参考。叠加历元分析的统计结果表明，超低频磁异常更可能出现在大地震（E-s>10（8））之前，而不是之后，尤其是震前6-15天。进一步的统计研究表明，KAK台的超低频地磁异常对更大、更近的事件更敏感。最后，我们用莫尔昌误差图评价了超低频地磁信号对局部大地震的探测信息。相对于泊松模型，概率增益约为1.6。上述结果表明，KAK超低频震磁现象中含有明显的前兆信息，有可能改善大震预报。
To clarify and verify the ultralow frequency (ULF) seismomagnetic phenomena, we have performed statistical studies on the geomagnetic data observed at the Kakioka (KAK) station, Japan, during 2001-2010. We investigated the energy of ULF geomagnetic signals of the frequency around 0.01 Hz using wavelet transform analysis. To minimize the influences of artificial noises and global geomagnetic perturbations, we used only the geomagnetic data observed at nighttime (LT 2: 30 A. M. to 4: 00 A. M.) and utilized observations from a remote station, Kanoya, as a reference. Statistical results of superposed epoch analysis have indicated that ULF magnetic anomalies are more likely to appear before sizable earthquake events (E-s>10(8)) rather than after them, especially 6-15 days before the events. Further statistical investigations show clearly that the ULF geomagnetic anomalies at KAK station are more sensitive to larger and closer events. Finally, we have evaluated the precursory information of ULF geomagnetic signals for local sizable earthquakes using Molchan's error diagram. The probability gain is around 1.6 against a Poisson model. The above results have indicated that the ULF seismomagnetic phenomena at KAK clearly contain precursory information and have a possibility of improving the forecasting of large earthquakes.