摘要
云南大理MS6.4地震和意大利拉奎拉(L'Aquila)MW6.3地震都因未能准确做出危险性预测给人民生命财产造成重大损失。哪些工作可能向政府和公众说明“哪里可能发生地震”、“最大量级多大”、“未来发震趋势如何”等问题都值得深入思考。本文根据天气预报思路,将地震活动按丛集性做分区处理,从各区M-t序列、3级地震活动性、2年来地震能量释放升级趋势、G-R关系等几方面分析了这两次地震主震发生前的地震活动特征,对比分析了它们之间的相似性。认为这两次地震的相似性有以下几点:①震源深度都比较浅。云南大理MS6.4地震震源深度8 km,意大利拉奎拉MW6.3地震震源深度8.8 km;②b值相近。云南大理MS6.4地震b=0.59,意大利拉奎拉MW6.3地震b=0.61。G-R关系外推震级相近,均为MGR6左右;③M-t图序列地震能量释放都呈升级趋势,地震活动也相似。平静打破后3级以上地震活跃,都出现震群现象,地震能量释放呈加速状态;④都属于前震-主震-余震型序列。意大利拉奎拉MW6.3地震主震前最大前震为MW5.2;云南大理MS6.4地震主震前最大前震为MS5.6,且前震震群特征明显。同时,本文讨论了按地震丛集性划分区域的合理性,认为按地震丛集性划分区域更容易把握区域地震活动的特点。这两次地震发生在不同区域,构造差异极大,属不同错动类型,用分区G-R关系和M-t序列分析,都得出较好的结果,再次说明了分区G-R关系和M-t序列分析对判断地震危险性的普适性特征,这为下一步产出“地震危险性云图”提供了依据。
Both Dali MS6.4 earthquake in Yunnan Province and the L'Aquila MW6.3 earthquake in Italy caused heavy losses of life and properties because they failed to make accurate hazard predictions.What might be done to inform the government and the public about the possible occurrence of an earthquake and its maximum magnitude? What is thetrend of earthquake in the future? In this paper,based on the idea of weather forecast,the seismicity is divided intoseveral regions according to the clustering. The characteristics of seismicity before the two main earthquakes are analyzedfrom the aspects of M-t sequence in each area,seismicity of 3-magnitude earthquakes,the trend of energy release andescalation in the past two years. The G-R relationship,and the similarities between the two earthquakes are compared andanalyzed. The similarities are as follows:① Both hypocenters are shallow. The source depth of Dali MS6.4 earthquakewas 8 km,and that of the L'Aquila MW6.3 earthquake in Italy was 8.8 km;② b values are similar. They are 0.59 and0.61,respectively. The G-R relation extrapolation magnitudes are close to each other,and they are all about magnitude6;③ The seismic energy release in M-t sequence shows an ascending trend,and the seismic activities are similar. Afterthe calm was broken,earthquakes of magnitude 3 or above were active,and earthquake swarms appeared. The release ofearthquake energy was accelerated;④ They all belong to foreshock-main shock-aftershock type sequence. The largestforeshock before the MW6.3 earthquake in Laquila,Italy,and the largest foreshock before the main-shock in Dali,Yunnan Province,are 5.2 and 5.6,respectively. And the characteristics of foreshock swarm are obvious. At the sametime,the paper discusses the rationality of dividing the region according to the clustering of earthquakes,and it isconsidered that it is easier to grasp the characteristics of regional seismicity using this method. Although Dali MS6.4earthquake in Yunnan and L'Aquila MW6.3 earthquake in Italy occurred in different area
作者
张晁军
Zhang Chaojun(China Earthquake Networks Center,Beijing 100045,China)
出处
《地震科学进展》
2021年第8期345-351,361,共8页
Progress in Earthquake Sciences
基金
基地专项−国家地震科学数据共享服务平台(99950513)资助。
