地震空区的定量判据

QUANTITATIVE CRITERION OF SEISMIC GAPS

在中国,孕震空区已经比较广泛地应用于地震预报的实践,并多次取得实际预测强震的效果。但经过系统震例研究发现,利用孕震空区预报地震的虚报漏报率比较高。本文运用解决临界相变问题的重正化群方法所求出的孕震空区可能发生失稳破裂,导致强震发生的判据对孕震空区的危险性作出进一步鉴别,并用突变论方法求解尖拐突变方程,预测孕震空区未来发生强震的时间和震级,并进一步确定孕震空区的危险性。对26个中国大陆强震前的孕震空区,运用上述方法系统研究结果表明:综合利用孕震空区识别标志,重正化群和突变论方法来鉴别孕震空区的危险性及预报未来地震发震的震级和时间,可以显著提高用空区预报地震的效果,其虚报率可减少到20％漏报率减少为0,从而使表征预报效果的R值从0.3左右增加到0.8左右。当然本文的结果尚须作进一步展望性检验,即对还未发生地震而出现孕震空区的情况进行研究,以期事先作出某种预报并确切估计出本方法的真实预报效率。

The preparation gap method has been extensively applied to earthquake prediction practice in China and some strong earthquakes are successfully forecasted with help of this method. It is found that the false alarm rate and rate of failing to forecast by using this method are still higher according to systematic study of earthquake cases. In this paper authors applied the renormalization group method, which has been used to the critical phase transformation, to give the criterion of strong earthquake occurrence due to crack's instable extesion possibly created in preparation gaps and further distinguish the risk of the preparation gaps, then to solve the cusp catastrophic equation with the catastrophism method to predict time and magnitude of future strong earthquake in the gaps, finally to get a better determination of earthquake risk in the preparation gaps. The method proposed in this paper is applied to the preparation gaps formed before 26 strong earthquakes in the mainland of China. The results show that the method which combines the index of prepqration gaps with renormalization group theory and catasrophism theory to identify the risk of preparation gaps and predict the magnitude and time of future earthquakes, may significantly improve the earthquake prediction. The false alarm rate of this method is reduced to 20%, the rate of failing to forecast is reduced to zero. Therefore, R value (represents the quality of prediction ) rises from about 0.3 to 0.8. The further perspective tests are necessary fqr the above-mentioned results and conclusions, that is, to study the cases in which preparation gaps have ocurred but no corresponding earthquakes observed, and to make some prediction for the possible earthquakes and to evaluate the efficiency of the method.