摘要
近年来,通过艰苦的野外现场考察和室内相关资料的系统调研,对1879年武都南8级大震的震级、震害、烈度分布、同震破裂及其形成该事件的发震构造、形成机制等方面的问题进行了专题研究。本文对武都南8级大震的宏观震中位置、震级及同震破裂研究结果进行了总结。重点讨论了该历史事件同震破裂的分布范围、破裂类型、规模及其形成机制等方面的问题。研究结果表明:(1)武都南地震的极震区主体位于甘肃东南部的武都与文县之间,且靠近武都南,为一呈北东东向展布的椭圆形,长轴长约70km,短轴长约30km,宏观震中位于极震区东部的堡子坝附近。(2)极震区内分布有3条向北东撒开,向南西收敛的同震破裂带。(3)主破裂带西起哈南白水江,东至固水子、透坊、稻畦子一带的白龙江沿岸。(4)同震破裂主要由地震裂缝、地震陡坎、地震鼓包、地震滑坡、堰塞湖等构造类型组成,其中以滑坡现象最为突出,保存也最为完整。(5)根据同震破裂的产生部位、几何结构和形成机制,可认为武都南地震的同震破裂带是在哈南-稻畦子-毛坡拉断裂带左旋走滑兼倾滑活动作用下形成的。(6)根据同震破裂的规模及发震断裂运动量实测数据,可以确定武都南地震震级已达8级。
Based on field investigation and indoor relative data analysis for the 1879 southem Wudu M8.0 earthquake, the magnitude, damage, intensity distribution, co-seismic raptures, causative fault and the mechanism of that earthquake is studied. The co-seismic ruptures of this earthquake, distribution range, types, scale and mechanism of those ruptures, etc. is emphasized in the paper. Research results indicate： ① The extreme seismic damage zone mainly located between Wudu and Wenxian, southeastern part of Gansu Province, forming a NEE extending ellipsoid with a long axis of more than 70km and a short axis of about 30km. ②Three rupture belts located in the extreme seismic damage zone, diverging in NE direction and converging in SW direction. ③The major rupture extend eastward from the Beishui River, Hanan to Bailong River close to Jiabanshan, Toufang and Daowazi.④The types of the co-seismic ruptures include： earthquake rent, scarplet, uplift, landslip, and blocked lake, in which the landslips are the most obvious and kept most completely. ⑤According to the co-seismic raptures＇ location, geometric structure, mechanism, these co-seismic raptures can be deduced to the results of the left-slip and dip-slip movement of the Hanan-Daowazi-Maopola fault belt.
出处
《中国地震》
CSCD
北大核心
2005年第3期295-310,共16页
Earthquake Research in China
基金
地震科学联合基金资助(震联基金批准号:101010号)
关键词
武都南地震
同震破裂带
发震断裂
地震滑坡
Southern Wudu earthquake
Co-seismic rupture
Causative fault
Earthquake slopes
