汶川8.0级地震强震动加速度记录的初步分析
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摘要
本文对国家强震动台网中心收集的2008年5月12日14时28分04秒汶川8.0级地震中获取的420组三分量加速度记录进行了处理和初步分析。在分析前对原始加速度记录进行整理、转换数据格式、零线校正、录入原数据,形成标准格式的未校正加速度数据;在这次地震中布设在龙门山断裂带及其周围地区有50多个台站获得了大于100 Gal的加速度记录,有46组三分量加速度记录的断层距小于100 km,使中国大陆近断层区域所获得的强震动加速度记录的数量成倍增加。本文依据这批数据对汶川大地震强震动特性进行了初步分析,给出了此次地震断层附近地区的PGA衰减规律,并利用此规律模拟断层附近的加速度峰值,绘制了PGA分布图;给出了汶川地震断层附近的加速度反应谱、上盘效应、速度大脉冲效应等地震动特征,这些特征可作为抗震设计规范修订的依据及灾区重建时参考;最后展望了这批强震动加速度记录的应用前景。
A total of 420 three-component acceleration records got from the Wenchuan Earthquake,which struck Sichuan,China at 14∶28∶04 on May 12th,2008 collected by China strong motion net center was processed and analyzed preliminarily.In order to get the standard format uncorrected accelerograms,the data format of the seismic original records was transformed,the base lines were corrected,and the metadata entry was done routinely before the normal analysis processing.There were more than 50 stations in Longmenshan Mountain fracture zone and its circumference,which obtained acceleration records.The maximum amplitudes of acceleration are greater than 100 Gal.The distances from the fault of 46 three-component acceleration records are less than 100 km.This made the amount of strong motion records obtained near-fault in Mainland China doubly increased.Based on the collected data,the basic characteristics of the strong ground motions of Wenchuan Earthquake were analyzed.According to the statistical analysis of PGA,the Wenchuan Earthquake specific attenuations were also given.We used this attenuation relationship to simulate the PGA of near-fault regions.The spatial distributions of the PGA are plotted.We gave out the basic characteristics of near-fault ground motion of this earthquake,such as the acceleration response spectra,the hanging wall effects,the rupture directivity effects,the fling step effecs and so on.These characteristics can be used as references in the seismic design code revision and disaster area reconstruction.Finally,the application of these seismic records is prospected.
A total of 420 three-component acceleration records got from the Wenchuan Earthquake,which struck Sichuan,China at 14∶28∶04 on May 12th,2008 collected by China strong motion net center was processed and analyzed preliminarily.In order to get the standard format uncorrected accelerograms,the data format of the seismic original records was transformed,the base lines were corrected,and the metadata entry was done routinely before the normal analysis processing.There were more than 50 stations in Longmenshan Mountain fracture zone and its circumference,which obtained acceleration records.The maximum amplitudes of acceleration are greater than 100 Gal.The distances from the fault of 46 three-component acceleration records are less than 100 km.This made the amount of strong motion records obtained near-fault in Mainland China doubly increased.Based on the collected data,the basic characteristics of the strong ground motions of Wenchuan Earthquake were analyzed.According to the statistical analysis of PGA,the Wenchuan Earthquake specific attenuations were also given.We used this attenuation relationship to simulate the PGA of near-fault regions.The spatial distributions of the PGA are plotted.We gave out the basic characteristics of near-fault ground motion of this earthquake,such as the acceleration response spectra,the hanging wall effects,the rupture directivity effects,the fling step effecs and so on.These characteristics can be used as references in the seismic design code revision and disaster area reconstruction.Finally,the application of these seismic records is prospected.
引文
[1]陈运泰,许力生,等.2008年5月12日汶川特大地震震源特性分析报告[R].中国地震局地球物理研究所网站汶川8.0级地震抗震救灾科技专题报道,2008.
[2]李小军,周正华,于海英,等.汶川8.0级地震强震动观测及记录初步分析[C]//汶川地震建筑震害分析与重建研讨会,北京,2008.
[3]中国地震局震害防御司.汶川8.0级地震未校正加速度记录[M].中国强震记录汇报,第十二集,第一卷,北京:地震出版社,2008.
[4]李政宽,罗俊雄,辛在勤.集集地震之地震观测及强地动分析[J].结构工程,1999,14(3):5-28.
[5]Chen Ji,Gavin Hayes.Finite fault model-Preliminary result of the May 12,2008Mw7.9 Eastern Sichuan,China Earthquake[R].The Web ofNational Earthquake Information Center(NEIC)of United States Geological Survey,2008.
[2]李小军,周正华,于海英,等.汶川8.0级地震强震动观测及记录初步分析[C]//汶川地震建筑震害分析与重建研讨会,北京,2008.
[3]中国地震局震害防御司.汶川8.0级地震未校正加速度记录[M].中国强震记录汇报,第十二集,第一卷,北京:地震出版社,2008.
[4]李政宽,罗俊雄,辛在勤.集集地震之地震观测及强地动分析[J].结构工程,1999,14(3):5-28.
[5]Chen Ji,Gavin Hayes.Finite fault model-Preliminary result of the May 12,2008Mw7.9 Eastern Sichuan,China Earthquake[R].The Web ofNational Earthquake Information Center(NEIC)of United States Geological Survey,2008.
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