用有限强地震动记录校正等震线的估计研究

Study on bias correction of ShakeMaps based on limited acceleration records

  • 摘要: 选用获得了加速度记录的2011年4月10日四川炉霍MS5.3及2011年8月11日新疆维吾尔自治区克孜勒尔自治州阿图什市与伽师县交界MS5.8地震,研究其快速生成震动图的偏差校正方法;通过台站实际观测值与借助经验性衰减关系估计值之间的残差分析,提出了利用台站数据对缺少台站地区借助经验性衰减关系估计值的对数偏差校正方法; 并比较了圆和椭圆衰减关系模型的对数残差及震动图的分布形态.结果表明, 适合于当地地震动衰减关系plusmn;3倍标准差的标准能够识别一些台站异常数据, 如炉霍MS5.3地震中炉霍地办强震台近场峰值加速度的高频脉冲引起的异常数据;对数偏差校正方法适合于地震动强度速报中缺少台站数据地区借助经验性衰减关系地震动参数估计值的系统偏差校正;圆衰减关系模型只能控制震动的程度,不能控制其分布形态.明确的地震震源机制、震源破裂过程、当地的地质构造背景及余震分布等信息有助于修正震动图的分布形态.

     

    Abstract: We investigated bias correction method of ShakeMaps based on limited acceleration records for the 10 April 2011 Luhuo, Sichuan, earthquake (MS5.3) and the 11 August 2011 Jiashi, Xinjiang, earthquake (MS5.8). By analyzing residuals between the observed data and calculated values, we proposed a method of logarithmic deviation correction for theoretical estimates in regions lacking seismic observations. We also compared both logarithmic residuals and vibration distribution between circle attenuation model and ellipse attenuation model. Research and analysis show that rules of plusmn;3 times standard deviation of local ground motion attenuation relations can remove some abnormal station data, such as the abnormal data from Luhuo Diban station for Luhuo earthquake due to near-field high-frequency acceleration pulses. During rapid report of ground motion intensity, the method of logarithmic deviation correction is suitable for systematic error correction of theoretical estimates of ground motion parameters. Circle attenuation model can only control the degree of vibration, but can not control its distribution. The information of focal mechanism, rupture process, local geological structure and distribution of aftershocks of an earthquake can help modify the distribution of ShakeMaps.

     

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