日本MW9.1地震对区域热辐射背景场影响的时频分析

Time-frequency analysis of the influence of Japan MW9.1 earthquake on regional thermal radiation background field

  • 摘要: 一次特大地震会对震中及附近区域热辐射背景场造成较大影响。应用中国静止气象卫星风云二号系列(FY-2C/2E/2F/2G)的亮温资料,通过时频相对功率谱法对2007—2016年(30°N—45°N,135°E—150°E)范围的时频数据进行全时空全频段扫描,得到了2011年3月11日日本MW9.1特大地震的热辐射异常,该异常特征明显且与地震发震构造对应较好。应用时频分析方法分析MW9.1地震对上述扫描区域热辐射背景场的影响,得出2011年的热辐射异常出现时间长、范围大且与其它年份不同,进而得到影响过程的3个阶段(出现—最大—消失)。同时对多尺度相对功率谱处理地震热辐射异常的异同和优缺点进行了对比研究,结果显示6阶小波变换尺度部分经不同窗长的相对傅里叶功率谱处理能更加有效地识别和提取地震热辐射异常信息,研究区域10年间共出现6次热辐射异常,其中两次与2011年地震对应,3次与该区域其它地震对应,仅1次无地震对应。

     

    Abstract: A major earthquake has a greater impact on the thermal radiation background field in and around the epicenter. The black body temperature (TBB) data in the region of (30°N—45°N, 135°E—150°E) from 2007 to 2016 which is from the Chinese stationary weather satellite series (FY-2C/2E/2F/2G) was processed using time-frequency relative power spectrum (T-F RPS for short) with full-time and full-band, and we got the thermal radiation anomalies. The result shows that the characteristics of thermal radiation anomalies are obvious and well corresponding to the seismogenic structure of the Japan MW9.1 earthquake on March 11, 2011. In addition, we used the time-frequency analysis method to analyze the influence of the MW9.1 earthquake on the thermal radiation background in the above region. It was found that a long-term thermal radiation anomaly in the region in 2011, which was inconsistent with other years, displayed as three phases from appearance to maximum and then to disappearance. Meanwhile, we compared the similarities and differences of seismic thermal radiation anomalies processed by multi-scale relative power spectrum. It is indicated that the relative Fourier power spectrum with the 6th-order wavelet transform is more effectively with different window lengths to extract and recognize the thermal radiation anomalies. A total of six thermal radiation anomalies occurred in ten years, among which twice occurred in 2011 and three anomalies corresponded to the earthquakes in other years of this area, and the remaining one anomaly had no earthquake to correspond to.

     

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