孕震过程中地震活动时空演化的非均匀特征
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摘要
运用刻画强震前中、小地震在时空分布上不均匀性的参量GL值方法 ,系统研究了华北地区 2 8次MS≥ 5 0中强震前GL≥ 1 0的高值异常在空间上的分布特征和时间上的变化特征 ,系统开展了该地区不同地震活动水平的计算震级下限、时间窗、空间窗的合理性研究 ;对计算中所选取的参数进行优化和修改 ;采用全时空扫描的方法研究、追踪华北地区历次中强震前GL值的异常变化。结果表明 :华北地区 82 %的中强震前约 1～ 3 5年内 ,在未来震中附近出现明显的高值异常区 ,地震多发生在异常区的边缘或附近。GL值异常区的时间曲线表明 ,异常持续时间为 3～ 2 5个月不等 ,异常持续时间优势分布为 3～ 14个月 ,约占总异常数的 78% ;异常结束后 ,地震发生的优势分布为 0～ 14个月 ,约占总异常数的 83%。由此认为 ,GL值方法可能成为华北地区中强震预测的一个较为有效的方法
Based on the GL\|value,a parameter describing inhomogeneities in temporal and spatial distributions of moderate and small earthquakes before strong earthquakes,the problems have been studied in the paper as follows:systematic investigations have been made on the features of spatial distributions and temporal variations of the high value anomalies(GL≥1\^0)prior to 28 moderate earthquakes with M\-S≥5\^0 in North China,a systematic study has been made on the reasonability of the lower limit of magnitude,the time window and the space window for calculations at various seismicity levels in this region;the parameters taken in the calculations have been optimized and modified;the anomalous variations of GL\|value prior to various moderate earthquakes in North China have been investigated and followed,using the total time\|space scanning method.The results have shown that for 82% of the moderate earthquakes in obvious anomalous region with high GL \|values appears near the future epicenter about 1～3\^5 years before the earthquakes in North China.The earthquakes usually occur in the marginal area of the anomalous zone or near it.Temporal variations of the GL \|values in the anomalous zone show that the duration of anomalies range between 3～25 months with a predominant interval of 5～19 months,into which about 70% of the total anomalies.The predominant interval of earthquake occurrences is 0～14 months after the end of anomaly,into which about 83% of the total anomalies.Based on thoe results,the GL\|value method is considered to be a rather effective prediction method for moderate earthquakes in north China.
Based on the GL\|value,a parameter describing inhomogeneities in temporal and spatial distributions of moderate and small earthquakes before strong earthquakes,the problems have been studied in the paper as follows:systematic investigations have been made on the features of spatial distributions and temporal variations of the high value anomalies(GL≥1\^0)prior to 28 moderate earthquakes with M\-S≥5\^0 in North China,a systematic study has been made on the reasonability of the lower limit of magnitude,the time window and the space window for calculations at various seismicity levels in this region;the parameters taken in the calculations have been optimized and modified;the anomalous variations of GL\|value prior to various moderate earthquakes in North China have been investigated and followed,using the total time\|space scanning method.The results have shown that for 82% of the moderate earthquakes in obvious anomalous region with high GL \|values appears near the future epicenter about 1～3\^5 years before the earthquakes in North China.The earthquakes usually occur in the marginal area of the anomalous zone or near it.Temporal variations of the GL \|values in the anomalous zone show that the duration of anomalies range between 3～25 months with a predominant interval of 5～19 months,into which about 70% of the total anomalies.The predominant interval of earthquake occurrences is 0～14 months after the end of anomaly,into which about 83% of the total anomalies.Based on thoe results,the GL\|value method is considered to be a rather effective prediction method for moderate earthquakes in north China.
引文
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傅征祥 ,1991,中国大陆东部强震活动时间的不均匀性研究 ,中国地震 ,7(2 ) ,115～ 12 7。
傅征祥 ,1997,中国大陆地震活动性力学研究 ,北京 :地震出版社 ,113～ 12 7。
李钦祖、于新昌 ,1980 ,华北地区大地震的成组活动特点 ,地震科学研究 ,(1) ,1～ 9。
李志雄、高 旭 ,1994,地震非均匀度的研究及在强震中期预报中的应用 ,地震 ,14(6 ) ,11～ 17。
刘桂萍 ,1999,地震非均匀度方法在华北地区中强地震中期预报中的应用 ,地震 ,19(1) ,5 4～ 5 8。
肖丽珠、柳永秀、石 航 ,1998,地震非均匀度在甘肃及邻区中强地震中短期预报中的应用 ,地震 ,18(2 ) ,189～ 193。
Keils borokV .I ,KnoplffL .,1980 ,Burstsofaftershockofstrongearthquakes ,Nature ,2 83 ,5 744 2 5 9～ 5 744 2 6 3 .
Mjachkin ,V .,W .Brace ,Sobolev ,G .andDieterich ,J .1975 ,Twomodelsofearthquakeforerunners ,PAGEOPE .,113 ,16 9～181
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