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ISSN 2096-7780 CN 10-1665/P

乌拉特后旗地震窗预测指标优化

Optimization of earthquake prediction indicators in Urad Rear Banner seismic window

  • 摘要: 乌拉特后旗地区位于阿拉善地块、鄂尔多斯地块和燕山地块的交界处,其地震活动受到构造应力场变化的影响,与中强地震的发生存在一定关联。自2022年10月以来,该地区的小震活动显著增强,超出背景水平。本文选取的地震窗口位于乌拉特后旗地区,以地震窗内2.0级以上地震在180 d内的累计频次作为开窗指标,目标地震为鄂尔多斯地块西北缘的5.0级以上地震,并以R值作为预测效能的评估参数。通过考察R值在预测窗长-阈值的二维参数空间内的分布,确定R值最高值对应的预测窗长和阈值作为预测规则。结果表明,R值最高为0.43,最终确定的预测窗长为200 d,报警阈值为8次。在此规则下,地震频次开窗预测指标显示出良好的预测效果和较高的可信度。

     

    Abstract: The Urad Rear Banner region is located at the intersection of the Alxa, Ordos, and Yanshan blocks. Seismic activity in this area is influenced by changes in the tectonic stress field and is correlated with the occurrence of moderate to strong earthquakes. Since October 2022, the region has experienced a significant increase in small earthquake activity, exceeding background levels. In this study, we analyzed a seismic window within the Urad Rear Banner area. The cumulative frequency of earthquakes with a magnitude of M 2.0 or greater in 180 days was used as the window-opening indicator. The target events were earthquakes with M≥5.0 events occurring along the northwestern edge of the Ordos block. Prediction effectiveness was evaluated using the R-value metric. By examining the distribution of R-values within the two-dimensional parameter space of the prediction window length and threshold, prediction rules were established based on the highest R-value. The results showed that the highest R-value was 0.43, with an optimal prediction window length of 200 days and an alarm threshold of eight events. Under these parameters, the frequency-based prediction indicator demonstrated good predictive performance and high reliability.

     

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