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Title:: Collation of the Vertical Slip Rate of Middle Segment of Huashan Frontal Fault Zone in Holocene

Author(s):: XU Jianhong; HUI Xuhui; HE Siyuan; (The Second monitoring and Application Center,CEA,Xian 710054,Shaanxi,China)

Keywords:: Huashan Frontal Fault Zone; Holocene vertical slip rate; normal fault

摘要:: 全新世以来,距今越近,华山山前断裂中段的垂直活动速率越大,甚至出现跳跃式的增长。重新梳理该断裂带40多处断层陡坎测量结果,发现这种不合理应与1556年华县8 级地震有关。通过减掉1556年华县大地震的同震位移量,消除了这次大震的同震位移对活动速率计算值的放大作用,而且不同时期地貌陡坎的计算结果均表现出了很好的稳定性,说明这种处理是必要和有效的。最后,应用上述处理方法得到了华山山前断裂中段全新世以来较为可靠的平均垂直活动速率为(1.56±0.2)mm/a。

Abstract:: There exit the unreasonableness that the vertical slip rate of the Huashan Frontal Fault jumpily becomes higher since Holocene when the period is shorter from present.Through reviewing the measuring results of more than 40 fault scarps of the Huashan Frontal Fault,we found that these unreasonable results are close related to the latest earthquake,Huaxian 8 earthquake in 1556.Subtracting the coseismic displacement of the Huaxian 8 earthquake in 1556,we eliminated its amplification effect on the calculated value of activity slip velocity.The calculated result of fault scarps in different periods show steady,which indicates that this processed method is necessary and effective.Finally,we applied this processed method to get a more reliable average value of vertical activity velocity of about 1.56 mm/a in the middle section of Huashan Frontal Fault zone since Holocene.