汉中盆地内梁山南缘断裂的活动性分析——以汉江大堤位置为例*
李晓妮,冯希杰,任 隽,李高阳,李 苗

(陕西省地震局,陕西 西安 710068)

梁山南缘断裂; 浅层地震探测; 钻探; 活动速率; 晚更新世

Activity Analysis of the Liangshan Southern Margin Fault in Hanzhong Basin——A Case Study of Hanjiang River Levee
LI Xiao-ni,FENG Xi-jie,REN Jun,LI Gao-yang,LI Miao

(Earthquake Administration of Shannxi Province,Xi'an 710068,Shannxi,China)

Liangshan southern margin fault; shallow seismic exploration; composite drilling section; activities rate; late Pleistocene

备注

为获取梁山南缘断裂在汉江大堤上断点的具体位置、近地表断错、上断点埋深、最新活动时代及滑动速率等信息,对其进行了浅层地震勘探和钻孔联合剖面探测。浅层地震解译结果显示断点两侧第四纪以来的12组反射波全被垂向错断,最大错距约370 m,影响带宽度约400 m,影响带内地层起伏强烈。钻探结果反映主断层晚更新世中期的最大错距约28 m,晚期错距约11 m,平均滑动速率为0.38～0.49 mm/a,上断点埋深为5～13 m,属于晚更新世晚期活动断层。

Using the shallow seismic and composite drilling section exploration,we obtained actual position of the breakpoint,near-surface dislocation,buried depth of upper breakpoint,the latest active time and slip rate of Liangshan Southern Margin Fault on the Hanjiang River Levee.Shallow seismic interpretation results show that 12 reflected wave groups are vertically leaped by Liangshan Southern Margin Fault since Quaternary period.Maximum dislocation of bottom interface of the fault is about 370 m,and the width of the influence belt is about 400 m.The strata undulate strongly in the influence belt.The drilling results reflect that the maximum dislocation of the main fault is 28.2 m in middle period of late Pleistocene,it is about 11 m on late period of late Pleistocene.The average slip rate of the main fault is about 0.38～0.49 mm/a and the buried depth of its upper breakpoint is about 0.38～0.49 mm/a.The Liangshan Southern Margin Fault is the active fault on late period of late Pleistocene.