则木河断裂带北段地震地貌及古地震研究

地震形成的构造微地貌是地震破裂在地表的直接证据,因此微地貌分析是古地震研究中的一种有效的方法。本文通过对则木河断裂北段大箐梁子一带发现的断层陡坎、断错冲沟、“搓衣板”地貌及坡中谷等地震地貌的研究,发现该断裂自晚更新世晚期以来至少发生过四次强震,其中历史上有记载的两次地震在地貌上也有所反映,说明在则木河断裂带上,强震亦具有在原地重复发生的特点。全新世以来,7级以上强震在原地复发的最小间隔约为1000年,其平均间隔约为1800年

EARTHQUAKE-CAUSED LANDFORMS AND PALEOSEISMIC STUDY ON THE NORTHERN SEGMENT OF THE ZEMUHE FAULT

Earthquake-caused landforms are the indicators of earthquake ruptures on the surface. Therefore the microgeomorphical analysis is an effective method in paleoseismic study. Through the study of newly found earthquake-related landforms (including fault scarps, offset gullies, wavy lands, and slopehanging-ditches) at Daqingliangzi, Xichang,Sichuan Province, at least four (may be seven) paleoseismic events of magnitude greater than 7 were identified. This result shows that strong earthquakes have occurred repetitively at the same place on the northern segment of the Zemuhe fault since later Pleistocene. Tne minimum time interval between every two strong earthquakes, on the northern segment of the Zemuhe fault is about 1000a during the Holocene-period, and the average time interval is about 1800a.