Analysis on M7.0 earthquake disaster in Zhangzha town of Jiuzhaigou

At 21:19 on August 8, 2017, the M7.0 earthquake broke out in Zhangzha town of Jiuzhaigou. The epicenter is located at (33.20°N, 103.82 °E), and the focal depth is about 20 kilometers. The earthquake epicenter is close to the Jiuzhaigou nature reserve, causing some damage to the protected areas, and leading to 20 deaths, more than 250 injuries, and nearly 40 thousand people trapped. In view of this great earthquake, the focal mechanism and damage form were emphatically analyzed in this paper. The results show that the Jiuzhaigou earthquake is a strike slip earthquake, and its moment magnitude is 6.5. Meanwhile, the fault section surface Ⅰ is a left-lateral normal faulting, and the dip angle and the slip angle are 62 degrees and –15 degrees respectively. Besides, the fault plane Ⅱ is right-lateral normal faulting, and the dip angle and the slip angle are 77 degrees and –151 degrees respectively. The maximum drift of the reinforced concrete frame structure exceeds the specified value in GB50011-2010. Moreover, it has a great influence on the long-span structure, and easily causes the collapse of buildings. In addition, due to the strike-slip type of earthquake, it’s easy to touch off landslide along with secondary disaster which increases the difficulty of rescue after the earthquake.