青海门源5.1级地震强震动记录及初步分析

Preliminary Analysis of Strong Ground Motion Records of the Menyuan MS5.1 Earthquake

摘要:

对西北强震动台网中心收集的2013年9月20甘肃肃南与青海门源交界5.1级地震的44组三分向加速度记录进行了处理和初步分析，给出了126条零基线校正后的三分向峰值加速度值。距震中37 km的63 MEY台加速度峰值约为50 gal，可得出该次地震震中烈度约为Ⅴ度，与震后的实际调查结果基本一致；选取了近场典型台站的加速度记录进行分析，绘制出了校正后的加速度时程曲线以及加速度反应谱，反应谱幅度及卓越周期的差别体现了震中距对地震传播和地震在不同场地环境中的影响。

Abstract:

The Northwestern Strong Motion Network Center is the strong-motion network data collection center for five provinces （Shaanxi，Gansu，Ningxia，Qinghai，Xinjiang）of northwestern China，and is responsible for the release of regional destructive-earthquake ground-motion information.An MS5.1 earthquake occurred at the junction of Sunan county，Zhangye city，Gansu province and Menyuan county，Qinghai province on September 20，2013，and the mainshock records of this earthquake obtained from 43 strong motion stations of the Northwestern Strong Motion Network are presented in the paper.The 43 strong motion stations are installed in Gansu，Qinghai province，and include two types of strong-motion seismographs：the MR2002 and ETNA.126 peak ground accelerations recorded by strong motion stations had been calculated after the zero baseline was corrected.The 63MEY strong motion station was closest to the epicenter，at a distance of 37.1 km，with a peak ground acceleration of 40.9 gal （EW），29.1 gal （NS），and 17.5 gal （UD）.The farthest station from the epicenter was 63TGM，at a distance of 220 km，with a peak ground acceleration of 1.5 gal （EW），1.5 gal （NS），and 0.9 gal （UD）.The effects of anisotropic media and site conditions may have resulted in unequal peak ground acceleration values for different locations with the same epicentral distance.The result is similar to the actual survey results after the earthquake，and therefore，the rapid reporting of intensity is very useful for earthquake emergency rescues.The acceleration records of these 43 stations substantially enhance the digital recording of the near-field strong-motion observations in the loess areas，and also provide fundamental data on seismic fortification，site effects，and intensity attenuation.