四川省地震堰塞湖灾害及其防御对策研究

Study on quake lake disasters and counter-measurements in Sichuan Province

通过公元前26年至今的2千余年发生在四川省境内的14次地震事件形成的堰塞湖的研究分析认为,1786年康定—泸定磨西743级地震、1879年7月1日甘肃武都8·0级地震、1933年茂县叠溪721地震、1976年松潘—平武7·2级地震和2008年汶川8·0级地震形成的堰塞湖造成严重的次生灾害;地震堰塞湖生成的重要背景条件为6级以上的强烈地震,所在区域地震烈度大于或等于Ⅷ度,地震堰塞湖的分布与活动性断裂关系密切。在上述背景下,地形切割明显的山区、不稳定边坡的存在以及降雨产生的泥石流等是形成地震堰塞湖的主要原因。

There were a lot of quake lakes caused by 14 strong earthquakes since 26 BC in Sichuan region. Some of them are, for instance, Kangding-Luding M7 3/4 Earthquake in 1786, Wudu MS. 0 Earthquake in 1879, Dianxi M71/2 Earthquake in 1933, Songpan-Pingwu MT. 2 Earthquake in 1976 and Wenchuan M8.0 Earthquake in 2008. These earthquakes caused heavy disasters and sub-disasters to people and properties. The basic condition forming quake lakes is that the seismic intensity is equal to or greater than M6.0 and, in other words, the seismic intensity is equal to or greater than VIII degree. The quake lakes distribute along the seismic zones and form in the mountain areas with step slops, unstable hill slopes and broken geological condition. Addition to natural environments mentioned above, the heavy rain and mud-rock flow are other necessary or main condition to form quake lakes. So we use the long-term earthquake forecasting to assess the security of hill slopes in mountain regions.