Wang Rui, Chang Ying, Miao Miao, Zeng Zhiyi, Chen Hongyan, Shi Haixia, Li Danning, Liu Lifang, Su Youjin, Han Peng
Department of Earth and Space Science, Southern University of Science and Technology, Shenzhen 518055, China.
Institute of Mining Engineering, BGRIMM Technology Group, Beijing 100160, China.
Entropy (Basel). 2021 Jun 8;23(6):730. doi: 10.3390/e23060730.
Many studies have shown that values tend to decrease prior to large earthquakes. To evaluate the forecast information in value variations, we conduct a systematic assessment in Yunnan Province, China, where the seismicity is intense and moderate-large earthquakes occur frequently. The catalog in the past two decades is divided into four time periods (January 2000-December 2004, January 2005-December 2009, January 2010-December 2014, and January 2015-December 2019). The spatial values are calculated for each 5-year span and then are used to forecast moderate-large earthquakes (M ≥ 5.0) in the subsequent period. As the fault systems in Yunnan Province are complex, to avoid possible biases in value computation caused by different faulting regimes when using the grid search, the hierarchical space-time point-process models (HIST-PPM) proposed by Ogata are utilized to estimate spatial b values in this study. The forecast performance is tested by Molchan error diagram (MED) and the efficiency is quantified by probability gain ( and probability difference (. It is found that moderate-large earthquakes are more likely to occur in low regions. The MED analysis shows that there is considerable precursory information in spatial values and the forecast efficiency increases with magnitude in the Yunnan Province. These results suggest that the value might be useful in middle- and long-term earthquake forecasts in the study area.
许多研究表明，在大地震发生之前，b值往往会下降。为了评估b值变化中的预测信息，我们在中国地震活动强烈且中大型地震频繁发生的云南省进行了系统评估。过去二十年的目录被分为四个时间段（2000年1月至2004年12月、2005年1月至2009年12月、2010年1月至2014年12月以及2015年1月至2019年12月）。每5年跨度计算一次空间b值，然后用于预测后续时间段内的中大型地震（M≥5.0）。由于云南省的断层系统复杂，为了避免在使用网格搜索时不同断层活动状态导致b值计算中可能出现的偏差，本研究采用了Ogata提出的分层时空点过程模型（HIST-PPM）来估计空间b值。预测性能通过Molchan误差图（MED）进行测试，效率通过概率增益（PG）和概率差异（PD）进行量化。研究发现，中大型地震更有可能发生在低b值区域。MED分析表明，空间b值中存在大量的前兆信息，且在云南省预测效率随震级增加。这些结果表明，b值可能对研究区域的中长期地震预测有用。
