Abstract: Based on field investigation and laboratory analysis,we discussed the slip mode of F₁ in thenorthern segment of the Yishu active fault in this paper. The macroscopic identification and analysis of the composition of clay minerals of fault gouge shows that it slowly sliped with the mode of creeping before late Pleistorene,while micro features indicate that it strongly stick-sliped before Pleistocene.Along with the study of chronology,it is preliminarily interpreted as variousstages from sticking-slipping slide to creep.This result is of practical significance to earthquakeprediction and engineering construction in the area nearby the Yishu fault zone.

Key words: Yisbu active fault segment, Stick－slip, Creeping, Late Pleistocene

摘要： 通过野外调查和室内分析,并结合对比南段全新世粘滑破裂的特征,对沂沭活断层北段F₁的滑动方式进行了讨论。断层泥SEM的判别结果表明,晚更新世(Q₃)以前,北段F₁以强烈的粘滑错动为主,而宏观调查及断层泥粘土矿物的分析显示出断层自晚更新世中晚期以来,其滑动方式可能由粘滑向蠕滑转变。结合年代学的研究,初步认为其转变时代为距今5万a左右。该结论对沂沭断裂带及其附近地区的地震预报及工程建设均具有实际意义和参考价值。

关键词: 沂沭活断层, 粘滑, 蠕滑, 晚更新世