| 2015年尼泊尔Gorkha地震强地面运动记录分析 |
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| 引用本文： | 李雪婧,高孟潭,吴健.2015年尼泊尔Gorkha地震强地面运动记录分析[J].地球物理学报,2017,60(9):3445-3456. |
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| 作者姓名： | 李雪婧 高孟潭 吴健 |
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| 作者单位： | 中国地震局地球物理研究所, 北京 100081 |
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| 基金项目： | 中国地震局地震行业专项（201408014）和国家科技支撑计划项目（2015BAK18B01-02）联合资助. |
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| 摘 要： | 2015年4月25日在尼泊尔Gorkha地区发生MW7.8地震，距离发震断层约11 km的KATNP台站完整记录了主震的加速度时程.本文根据KATNP台站记录的加速度数据分析了Gorkha地震的地震动特征.结果表明Gorkha地震在KATNP台站处产生的水平向峰值加速度为0.17 g，竖直向峰值加速度为0.19 g，该数值小于科学家们对如此大规模地震产生的地震动的预期，初步推测这可能是由加德满都山谷产生的非线性响应造成的（Dixit et al.，2015）；地震在KATNP台站处产生了地表永久位移，其中竖向永久位移为131.9 cm，水平向永久位移的绝对值为159.2 cm，方向为南偏西19°（199°），据此可简单推算出断层走向约为289°（109°）.地震产生了脉冲型地震动，影响因素有盆地效应、地震破裂的向前的方向性效应以及滑冲效应，其中盆地效应的周期约为5 s左右，方向性效应产生的速度脉冲的周期约为8 s左右.加速度反应谱显示在0.5 s和5.0 s左右各有一个峰值，前者是由地震破裂的脉冲式滑移产生的大量高频地震动造成的，后者是由于盆地效应和地震破裂的方向性效应造成的.基于阿里亚斯烈度计算的地震动持时约在36~46 s之间，小于与其规模相当的地震产生的地震动持时，并且不同方向上的地震动持时可能与地震破裂方向有关.阿里亚斯烈度随时间的变化比较简单，也反映了Gorkha地震是一次连续的、能量释放相对简单的地震事件.
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| 关 键 词： | 尼泊尔 Gorkha地震 地震动时程 强地面运动特征 |
| 收稿时间： | 2016-10-27 |
Analysis of strong-motion characteristics of the 2015 Gorkha,Nepal,Earthquake |
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| LI Xue-Jing,GAO Meng-Tan,WU Jian.Analysis of strong-motion characteristics of the 2015 Gorkha,Nepal,Earthquake[J].Chinese Journal of Geophysics,2017,60(9):3445-3456. |
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| Authors: | LI Xue-Jing GAO Meng-Tan WU Jian |
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| Affiliation: | Institute of Geophysics, China Earthquake Administrator, Beijing 100081, China |
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| Abstract: | In this paper, we use the acceleration data at KATNP station, about 11 km from the seismogenic fault, which completely recorded the acceleration time history of the main shock of Gorkha earthquake that occurred in Gorkha district of Nepal on April 25, 2015, to analyze its ground motion characteristics. The results of our research show that at KATNP station, the horizontal peak ground acceleration (PGA) is 0.23 g, and the vertical PGA is 0.19 g. Those values are less than the ones expected by researchers, which was preliminary speculated by Dixit et al.(2015) that this may be caused by the nonlinear response of the Kathmandu valley. Gorkha earthquake caused permanent surface displacement at KATNP station, of which the horizontal displacement is 159.2 cm, the direction is 199°, and the vertical displacement is 131.9 cm. According to those calculated results, we can simply determine the fault strike is 289°(109°). The possible reasons which cause pulse-like ground motions are the basin effect, the rupture forward directivity and the fling step, of which the period of basin effect is about 5 s, and the period of forward directivity pulse is about 8 s. There are two peak values at about 0.5 s and 5.0 s on the acceleration response spectrum; the former is due to rich high frequency ground motion caused by the pulse-type sliding of earthquake rupture, the latter is due to the basin effect and the rupture forward directivity. The duration of strong ground motion is about 36~46 s based on Arias intensity, less than the one caused by the earthquake of comparative size, and the duration of earthquake ground motion in different directions are likely related to the direction of earthquake rupture. Arias intensity changing over time also reflects that the Gorkha earthquake rupture time history is relatively simple, suggesting an uninterrupted rupture. |
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| Keywords: | Nepal Gorkha earthquake Earthquake ground motion time-history Characteristics of strong ground motion |
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