| 尼泊尔Ms8.1地震前我国西藏及周边区域的重力长期变化 |
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| 引用本文： | 康开轩,李辉,刘少明,郝洪涛,邹正波.尼泊尔Ms8.1地震前我国西藏及周边区域的重力长期变化[J].大地测量与地球动力学,2015,35(5):742-746. |
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| 作者姓名： | 康开轩 李辉 刘少明 郝洪涛 邹正波 |
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| 摘 要： | 根据1998~2013中国地壳运动观测网络、中国数字地震观测网络工程和中国大陆构造环境监测网络流动重力观测成果,给出了中国西藏及周边地区的重力年变率分布。结合青藏高原冰川消融和高原湖泊水位变化,估算了由陆地水储量变化引起的区域重力效应。基于50km平滑半径的高斯滤波,给出了测区内15a时间尺度的重力变化空间分布,并初步探讨了尼泊尔Ms8.1地震孕育的重力场长期背景趋势变化。结果表明:1)流动重力典型测点的时间序列表现出明显的线性变化特征,表明测点附近区域的长期重力变化以线性上升趋势为主,反映了区域重力逐年累积增加的背景效应;2)中国西藏及周边区域的重力长期变化在空间分布上具有显著的不均匀性和分区现象,这与青藏高原复杂的变形构造和动力学系统密切相关。喜马拉雅活动构造带在15a时间尺度上明显呈正重力变化趋势,可能与印度板块与欧亚板块存在的持续挤压变形引起的地下物质重新分布与调整有关,反映了大震孕育过程中地壳变形和介质变化引起的震区周围应力与能量的累积。
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| 关 键 词： | 青藏高原 重力观测 重力变化 尼泊尔地震 |
Long-Term Gravity Changes in Tibet and Its Vicinity before the Nepal Ms8.1 Earthquake |
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| KANG Kaixuan,LI Hui,LIU Shaoming,HAO Hongtao,ZOU Zhengbo.Long-Term Gravity Changes in Tibet and Its Vicinity before the Nepal Ms8.1 Earthquake[J].Journal of Geodesy and Geodynamics,2015,35(5):742-746. |
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| Authors: | KANG Kaixuan LI Hui LIU Shaoming HAO Hongtao ZOU Zhengbo |
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| Abstract: | Using measurements from three national repeated gravity networks-the crustal movement observation network of ChinaⅠ, digital earthquake observation network of China, and the crustal movement observation network of China during 1998-2013, we obtain the annual gravity rate in Tibet and
its vicinity. Based on the lake level change in Qinghai-Tibet Plateau, we estimate the gravity effects due to the continental water storage changes at each site. Finally, we obtain the spatial distribution of the long-term gravity changes in Tibet and its vicinity through spatial Gaussian filter with 50 km smooth radius. From our research we find: 1) The time series at typical gravity stations show a clear linear trend, which means the linear trend is the principal characteristic at those stations. The positive linear trend implies accumulated regional gravity changes in the past decades. 2) The long-term gravity changes in Tibet and its vicinity show uneven spatial distribution, which might be related with the complicated crustal deformation and geodynamical mechanisms in the Qinghai-Tibet Plateau. The Himalayan tectonic block shows a significant positive gravity annual rate, which might be related to underground mass redistribution and adjustment caused by continuous extrusional deformation between the Indian and the Eurasian plates. The positive gravity variations might indicate the stress and energy acceleration surrounding the locality of the earthquake due to the crustal deformation and medium changes during the process of earthquake preparation. |
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| Keywords: | Qinghai-Tibet Plateau gravity observation gravity variation Nepal earthquake |
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