汶川地震中鲜水河断裂带的隔震效应
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摘要
本文以汶川地震中的非发震断层鲜水河断裂带周边石棉地区所获取的加速度记录为依据,研究了这些记录在峰值、频谱间的差异。结果表明,以鲜水河断裂带为界,近震源侧地震动强度更大且高频更丰富。对该地区区域构造特征初步分析表明,鲜水河断裂带对汶川地震产生的地震动具有隔震效应。基于显式有限元和局部透射人工边界的二维有限元断层场地模型,对该地区的地面运动模拟结果表明,入射波动所指向的一侧地面运动更小,说明较陡的断层破碎带对斜入射地震波具有一定的隔震效应。
In this study, we analyzed the peak ground acceleration( PGA) and spectral characteristics of the earthquake acceleration records from the main shock of Wenchuan earthquake,the difference of the ground motion at both sides of the Xianshuihe fault zone. We found anomalously large amplitude and extremely rich high frequency in the ground motion near source side(right side of the fault in this case).Our results indicate that the non-causative fault(Xianshuihe fault zone)can obstruct the spread of seismic wave,and the isolation effect of the non-causative fault is presented. Numerical solution of 2-D model of this fault site derived by the explicit finite element combining with local multi-transmitting artificial boundary method is used for interpreting the mechanism of difference of the ground motion. The study of 2-D vertical low velocity fault zone( LVFZ) model struck by external oblique incidence seismic radiation shows that vertical LVFZ can obstruct the spread of oblique incidence seismic wave.
In this study, we analyzed the peak ground acceleration( PGA) and spectral characteristics of the earthquake acceleration records from the main shock of Wenchuan earthquake,the difference of the ground motion at both sides of the Xianshuihe fault zone. We found anomalously large amplitude and extremely rich high frequency in the ground motion near source side(right side of the fault in this case).Our results indicate that the non-causative fault(Xianshuihe fault zone)can obstruct the spread of seismic wave,and the isolation effect of the non-causative fault is presented. Numerical solution of 2-D model of this fault site derived by the explicit finite element combining with local multi-transmitting artificial boundary method is used for interpreting the mechanism of difference of the ground motion. The study of 2-D vertical low velocity fault zone( LVFZ) model struck by external oblique incidence seismic radiation shows that vertical LVFZ can obstruct the spread of oblique incidence seismic wave.
引文
何玉林,何宏林,李勇,2006.大型变电站厂址的地震地质条件研究——四川省石棉地区变电站遴选实例.中国地震,22(4):382—393.
卢寿德,李小军,2008.汶川8.0级地震未校正加速度记录.北京:地震出版社.
廖振鹏,2002.工程波动理论导论(第二版).北京:科学出版社.
刘必灯,2011.断陷盆地及断层破碎带场地地震动效应[博士学位论文].哈尔滨:中国地震局工程力学研究所.
2四川省地震局,2004—2007.四川省地震台站建台报告系列材料.
3四川省地震局工程地震研究院,2004.大渡河大岗山水电站工程场地地震安全性评价.
1四川省地震局,2004—2007.四川省地震台站建台报告系列材料.
卢寿德,李小军,2008.汶川8.0级地震未校正加速度记录.北京:地震出版社.
廖振鹏,2002.工程波动理论导论(第二版).北京:科学出版社.
刘必灯,2011.断陷盆地及断层破碎带场地地震动效应[博士学位论文].哈尔滨:中国地震局工程力学研究所.
2四川省地震局,2004—2007.四川省地震台站建台报告系列材料.
3四川省地震局工程地震研究院,2004.大渡河大岗山水电站工程场地地震安全性评价.
1四川省地震局,2004—2007.四川省地震台站建台报告系列材料.
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