青海热水—日月山断裂带古地震的初步研究

A PRELIMINARY STUDY ON PALAEO-EARTHQUAKE EVENTS OF THE REISHUI-RIYUE MT. ACTIVE FAULT ZONE IN QINGHAI PROVINCE

热水—日月山断裂带是青藏高原东北缘柴达木—祁连山活动地块内部一条重要的NNW向的右旋走滑活动断裂带.断裂活动形成了一系列山脊、冲沟和阶地等右旋断错微地貌及断层崖、断层陡坎等垂直断错微地貌.本文对发生在该断裂带上的古地震事件开展了研究,综合探槽剖面和断层陡坎年代,大致可以确定两次古地震事件,其年代分别为距今6280±120a,2220±360a,复发间隔约4000a左右.

Reishui-Riyue Mt. active fault zone is a very important NNW oriented rightlateral strikeslip active fault zone which developed in the Chaidam-Qilian Mt. active crustal block,northeastern margin of Qinghai-Tibet Plateau.The activity of the fault causes a series of microgeomorphologies,such as ridge, valley and terrace,rightlateral offseted and forms fault cliff and fault scarp et al. vertical offset microgeomorphology.In this paper,the palaeoearthquake events on the fault are studied.Combining the trench profiles and fault scarp measurement,two palasoearthquake events are determined,which occured in 6 280±120 a B.P. and 2 220±360 a B.P.,the recurrence interval is about 4 000 a.