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《地震研究》[ISSN:1000-0666/CN:53-1062/P]

卷:

44

期数:

2021年04期

页码:

613-621

栏目:

出版日期:

2021-11-10

文章信息/Info

Title:

Vertical Deformation in the Northern Section of the North-South Seismic Belt before and after the Wenchuan M_S8.0 Earthquake Based on GPS Data

作者:

梁洪宝; 杨国华

(中国地震局第一监测中心,天津 300180)

Author(s):

LIANG Hongbao; YANG Guohua

(First Crust Monitoring and Application Center,China Earthquake Administration,Tianjin 300180,China)

关键词:

GPS;  汶川M_S8.0地震;  南北地震带北段;  垂向形变

Keywords:

Global Positioning System;  the Wenchuan M_S8.0 earthquake;  the Northern section of the North-South Seismic Belt;  vertical deformation

分类号:

P315.72

DOI:

-

摘要:

2008年汶川M_S8.0地震对南北地震带北段垂向变形产生了影响,对1999—2016年多期GPS观测数据进行精密解算,采用多面函数方法分别对研究区垂向运动进行周年运动剔除和空间滤波,获取了汶川地震前后垂向形变特征。结果表明:①以巴颜喀拉块体与华南块体交界带西侧为界,其西部自东向西呈指数函数衰减; 东部自西向东呈对数函数形式衰减,且东部衰减程度大于西部,两块体交界南北段垂向形变特征存在差异性,北段隆升速度和变化梯度均弱于南段; ②地震前后南北地震带北段垂向形变特征具有明显差异性,相对震前,震后大部分区域隆升速度加快,平均约为2 mm/a,局部区域加快程度较大,最大值达7 mm/a; ③垂向速度的差异性变化对地壳的垂向应变积累具有影响,最大正影响区域为巴颜喀拉块体与华南块体交界及其西侧区域,增大了约10×10^-8/a,约为震前的2倍,最大负影响区域为川滇块体北部局部区域,减小了约7×10^-8/a 。建议对巴颜喀拉块体与华南块体交界及其西侧区域和川滇块体北部局部区域强化跟踪分析。

Abstract:

In view of the influence of the 2008 Wenchuan M_S8.0 earthquake on the vertical deformation of the northern segment of the North-South Seismic Belt,we calculate with high precision the multi-period GPS observation data during 1999-2016,the features of vertical deformation before and after earthquake are obtained by using the method of polyhedral function to eliminate annual motion and spatial filtering respectively.The results show that:① In the west side of the junctions of the Bayan Har Block and the South China Block,the vertical deformation attenuates from the east to the west in the form of an exponential function,while in the west side the vertical deformation attenuates from the west to the east in the form of a logarithmic function,and the attenuation in the east is greater than in the west.The vertical-deformation characteristics in the north are different from the ones in the south of the two Blocks' junctions.The uplift rate and the change gradient in the northern section are weaker than the ones in the southern section.② The vertical deformation of the Northern section of the North-South Seismic Belt before the Wenchuan earthquake was obviously different from the one after the earthquake.The uplift rate accelerates in most areas after the earthquake,with an average of about 2 mm/a and a maximum of 7 mm/a in the local area.The uplift rate of the local area decreases and the amplitude decreases within 2 mm/a.③ The variation of the vertical velocity has an effect on the vertical strain accumulation in the Crust.The largest positive influenced area is the junction of the Blocks and its western region,with increments about 10×10^-8/a and about 2 times of the ones relative to pre-earthquake.The largest negative influenced region is the northern part of the Sichuan-Yunnan Block,with a reduction about 7×10^-8/a.It is necessary to conduct an intensive GPS observation of the junction between the Bayan Har Block and the South China Block and its western region as well as the northern part of the Sichuan-Yunnan Block should be strengthened.

参考文献/References:

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备注/Memo

备注/Memo:

收稿日期:2021-02-02
基金项目:国家自然科学基金项目(41974011)和国家重点研发计划课题(2018YFC1503606)联合资助.

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更新日期/Last Update: 2021-11-10