基于跨断层水平形变资料的鲜水河断裂现今活动分析  

Analysis of the Current Activity on the Xianshuihe Fault from Cross-fault Horizontal Deformational Data

作　　者：唐伟[1] 苏琴[1] 李菲菲[1] 彭丽媛 竹任国 TANG Wei;SU Qin;LI Feifei;PENG Liyuan;ZHU Renguo(Sichuan Earthquake Agency Crustal Deformation Observation Center,Sichuan Ya'an 625000,China)

机构地区：[1]四川省地震局地壳形变观测中心,四川雅安625000

出　　处：《四川地震》2023年第1期26-31,共6页Earthquake Research in Sichuan

基　　金：四川省地震局地震科技专项(LY2116)资助。

摘　　要：利用2000—2018年鲜水河断裂基线、蠕变资料,将场地缩放到统一尺度,分析不同资料反映的断裂活动特征,探讨断层活动与周边地震活动的关系。结果显示:①跨断层近场水平形变资料表明鲜水河断裂活动具有明显分段性,按照断层活动速率大致分为北西段、中段和南东段,与地质上分段方式有一定差异;②跨断层近场水平形变资料能不同程度显示出偏离正常背景的活动变化,捕捉到附近中强地震前兆信息和震后调整变化,为地震危险性判定提供重要参考;③基线和蠕变反映的断层活动存在差异,基线活动明显高于蠕变,基线走滑速率为0.30~2.05 mm/a,张压速率为0.47~1.21 mm/a,蠕变走滑速率为0.14~0.62 mm/a,张压速率为0.12~0.29 mm/a;④蠕变和基线均显示研究区内的鲜水河断裂以左旋走滑活动为主,北西段和中段活动强于南东段,基线资料显示2017年芦山M_(S)7.0地震后张压活动总体加强。We used the baseline and creep data across the Xianshuihe fault from 2000 to 2018 and considered the site at an unified scale to reveal characteristics of fault activity based on different data.Moreover,we further discussed the relationship between the surrounding seismicity and fault activity.The results showed that:①The near-field horizontal deformational data across the fault indicated that the Xianshuihe fault activity shows an obvious segmentation.We suggest that the fault can be roughly divided into north-west section,middle section,and south-east section according to the fault activity rate,which was different from the geological segmentation mode.②The near-field horizontal deformational data across the fault can show active changes deviated from the normal background to varied degrees.This can capture precursor information of nearby medium and strong earthquakes and changes of post-earthquake adjustment,which provides important implications for determination of seismic risks.③Some differences in the fault activity were observed by the baseline and creep measurement.The baseline activity is significantly higher than the creep.Specifically,the baseline slip rate and tensile rate are 0.30~2.05 mm/a and 0.47~1.21 mm/a,whereas the creep slip rate and tensile rate are 0.14~0.62 mm/a and 0.12~0.29 mm/a.④Both creep and baseline measurement data showed that the Xianshuihe fault in the study area was dominated by a left-lateral slip.In addition,the activity on the north-west section and middle section was stronger than that on the south-east section.Baseline data show that tensile pressure activity has generally strengthened after the Lushan earthquake.

关 键 词：蠕变 基线 鲜水河断裂 断层活动特征 

分 类 号：P315.725[天文地球—地震学]