尹鹏, 张永志, 焦佳爽, 槐岩珂. 2018: 基于GRACE数据的尼泊尔MS8.1地震北向重力梯度变化. 地震学报, 40(1): 67-78. DOI: 10.11939/jass.20170141
引用本文: 尹鹏, 张永志, 焦佳爽, 槐岩珂. 2018: 基于GRACE数据的尼泊尔MS8.1地震北向重力梯度变化. 地震学报, 40(1): 67-78. DOI: 10.11939/jass.20170141
Yin Peng, Zhang Yongzhi, Jiao Jiashuang, Huai Yanke. 2018: Northern gravity gradient changes of the Nepal MS8.1 earthquake derived from GRACE data. Acta Seismologica Sinica, 40(1): 67-78. DOI: 10.11939/jass.20170141
Citation: Yin Peng, Zhang Yongzhi, Jiao Jiashuang, Huai Yanke. 2018: Northern gravity gradient changes of the Nepal MS8.1 earthquake derived from GRACE data. Acta Seismologica Sinica, 40(1): 67-78. DOI: 10.11939/jass.20170141

基于GRACE数据的尼泊尔MS8.1地震北向重力梯度变化

Northern gravity gradient changes of the Nepal MS8.1 earthquake derived from GRACE data

  • 摘要: 利用德克萨斯大学空间研究中心发布的GRACE RL05月重力场模型数据,采用300 km扇形滤波,得到2015年尼泊尔MS8.1地震北向重力梯度的时空分布,之后利用最小二乘拟合方法分析尼泊尔及其邻近区域北向重力梯度的长期变化趋势及研究区内6个特征点的北向重力梯度月变化时间序列,并结合黏弹性分层位错理论对GRACE检测尼泊尔MS8.1地震北向重力梯度同震变化的可能性进行分析. 研究结果表明:在尼泊尔MS8.1地震发生前北向重力梯度表现出比较明显的正负异常变化,而该地震即发生在北向重力梯度正负变化的零值线附近;研究区北向重力梯度年变率在印度板块边界及其垂直方向所形成的四象限呈正负相间分布,6个特征点的北向重力梯度在2012年4月出现比较明显的跳变. 由此推断,北向重力梯度的动态变化过程反映了震前区域物质迁移和震后壳幔物质黏滞性调整等问题.

     

    Abstract: Based on the RL05 monthly gravity field model released by Center for Space Research, University of Texas at Austin (UTCSR), the spatio-temporal distribution of northern gravity gradient of the Nepal MS8.1 earthquake is successfully obtained by using 300 km Fan filter. Then we analyzed both the long term change tendency in Nepal and its vicinity areas and monthly time series at six feature points of the northern gravity gradient by the least-squares fitting method. Furthermore, the possibility of the detection on coseismic change of the northern gravity gradient in the Nepal MS8.1 earthquake by GRACE is discussed combined with the viscoelastic-gravitational dislocation theory as well. The results show that, the positive and negative anomaly of the northern gravity gradient is obvious before the Nepal MS8.1 earthquake, which occurred in the vicinity of the zero line; the annual change rate of the northern gravity gradient presents positive and negative distribution in the four quadrants along the Indian Plate boundary and its vertical direction in the studied area, and the northern gravity gradient at the six feature points shows obvious jump in April 2012. Therefore, it is deduced that the dynamic change process of northern gravity gradient reflects mass migration before the earthquake and viscosity adjustment of crust and mantle after the earthquake in Nepal and its vicinity areas.

     

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