Abstract:

At 7: 45 on July 22,2013,an M_S6.6 earthquake hit Minxian County(34.5°N,104.2°E)of Dingxi City in Gansu Province,which brought 95 deaths and after which an emergency response of second grade was declared by China Earthquake Administration. In this earthquake,the intensity of the meizoseismal region is Ⅷ.Buildings in quake-hit region are mainly of civil structure and timber structure,which account for more than 90%.Unfortunately the anti-seismic ability of these two kinds of buildings is poor. To make things worse,most of them are old. And it had been rainy for days before the earthquake,which lowered the support ability of the foundation and the wall. After the earthquake,in comparison with other earthquakes,buildings of civil structure and timber structure are damaged more heavily in the region of the same intensity,and the damage of buildings of both brick structure and brick-concrete structure is obviously lighter. Significantly thick loess coverage and continuous rainfall gave birth to many landslides. For these reasons,the regions of both Ⅷ and Ⅵ intensity are relatively larger. Dingxi City,which the earthquake hit,is one of the most undeveloped regions in China,and the proportion of buildings of civil structure and timber structure,which behaved badly in the earthquake,is abnormally large. Thus it is suggested that the reconstruction aid should be expanded so that buildings can be built with the masonry-timber and brick-concrete as the main structures.

Key words: Minxian-Zhangxian M_S6.6 earthquake, earthquake hazard, emergency science research

摘要：

2013年7月22日在甘肃省定西市岷县—漳县交界地区(34.5°N,104.2°E)发生M_S6.6地震,造成95人死亡,中国地震局启动地震应急Ⅱ级响应。根据现场调查,这次地震最高烈度为Ⅷ度。震区建筑90%以上为土木结构和木结构,且多为老旧房屋,抗震性能差。加之震前灾区持续降雨,造成房屋地基和生土墙体支撑强度降低。与其他地震区相比,相同烈度下土木结构和木结构破坏比例偏大,砖结构和砖混结构破坏明显偏轻。降雨加上巨厚的黄土沉积,导致地震滑坡比较严重。由于这些原因,Ⅷ度区范围偏大,Ⅵ区也相对较大。甘肃定西是中国经济欠发达地区之一,土木结构和抗震性能较差的木结构房屋比例过大。震后重建中,建议以砖木结构和砖混结构为主重建灾区。

关键词: 岷县漳县M_S6.6地震, 震害, 应急科考