【作者】 陈皓；

【导师】 陶庭叶； 李水平；

【作者基本信息】 合肥工业大学 ， 大地测量学与测量工程， 2022， 硕士

【摘要】 全球导航卫星系统(Global Navigation Satellite System,GNSS)不仅可以用于定位、导航和授时,现如今也在地壳形变监测和地球物理反演领域的研究中提供了重要的帮助。随着中国大陆构造环境监测网络项目(Crustal Movement Observation Network of China,CMONOC)以及连续运行参考站(Continuously Operating Reference System,CORS)的发展,我们可以利用GNSS观测数据实现更高精度的区域地壳形变研究以及断层活动特征的反演。本文的研究对象为郯庐断裂带中南段,它由北向南跨越多个块体,内部构造复杂,尤其是第四纪以来地震灾害频发。在过去的几十年,郯庐断裂带周边曾发生了多次大型地震,例如2008年汶川Ms 8.0级地震和2011年日本宫城Mw 9.0级地震。因此,郯庐断裂带的运动性质可能会受到这些地震远场震后效应的影响。而该地区目前缺少地壳形变和应变积累的详细研究,这个人口稠密区域的地震危险性仍不可得知。本文的工作主要包括三个部分:一是解算安徽CORS(Anhui Continuously Operating Reference Stations,AHCORS)的观测数据,得到欧亚框架下的高精度速度场,并与公开的CMONOC速度场数据融合。二是利用多尺度球面小波和最小二乘配置法分别计算郯庐断裂带中南段的应变场,通过对比分析主应变率、面膨胀率以及最大剪应变率的结果,来讨论局部地区的应变分布特征。三是基于GPS速度场矢量数据,利用负位错模型反演并分析郯庐断裂带中南段震间的闭锁程度、闭锁深度以及滑动亏损速率的空间分布,并以此来评估研究区域的地震危险性。以下为本文的主要研究成果:(1)利用GAMIT/GLOBK软件解算了2013年1月～2018年6月之间近6年的AHCORS参考站的观测数据。获得了在国际地球参考框架2008(International Terrestrial Reference Frame,ITRF)下的坐标时间序列以及速度场。为了更精确地分析区域的运动特征,将ITRF2008框架下的速度场转换到欧亚框架下。速度场结果表明:AHCORS参考站在欧亚框架下的速度主要往东偏南方向运动,与公开的CMONOC站的速度场数据表现基本一致。通过速度剖面结果可知,平行于剖面的速度在-0.76～-0.35mm/a之间,垂直于剖面的速度在-0.44～-0.29 mm/a之间,郯庐断裂带中南段的运动特征表现为右旋和压缩。(2)利用多尺度球面小波和最小二乘配置法分别计算郯庐断裂带中南段的各应变参数。结果表明:对于主应变率,最小二乘配置法显示郯庐断裂带中南段的潍坊-郯城段附近主应变率几乎为0;而郯城-嘉山段为主应变率的高值区。以郯庐断裂带为界,西侧表现为近E-W向和N-S向的拉伸,东侧表现为NE-SE向或NW-SE向的拉伸;嘉山-桐城段主应变率相对较小,其东侧表现为近E-W向的拉伸,西侧以近N-S向的压缩为主。多尺度球面小波法的主应变率结果表现与其较为相似。对于面膨胀率,最小二乘配置法显示最大值出现在郯城-嘉山段的西侧,表现为面膨胀状态,大小为3.78×10;~8/(6。而多尺度球面小波的结果可以反映出更小区域范围内的应变积累特征。在郯城-嘉山段西侧的北部表现为面压缩状态,而南部表现为面膨胀状态。对于最大剪应变率,最小二乘配置法显示郯庐断裂带中南段上的最大剪应变率比郯城-嘉山段的两侧和桐城的东侧小。而多尺度球面小波法的结果也表现出近似的特征,只是在大小上比最小二乘配置法得出的结果稍大。(3)将同处于欧亚框架下的AHCORS速度场与CMONOC速度场融合,得到一个“新”的速度场。将GPS速度场矢量数据作为约束,采用负位错模型反演了郯庐断裂带中南段的活动特征。结果表明:对于闭锁程度和闭锁深度来说,相比于郯庐断裂带中南段的郯城-嘉山段和嘉山-桐城段,潍坊-郯城段的闭锁程度更高、闭锁深度更深、滑动亏损速率也更大,这意味着该段更容易产生应变积累。总的来说,郯庐断裂带中南段的潍坊-郯城段应变积累的速度更快,发生地震危险性的可能也更大。总体上,长周期的大震复发间隔是郯庐断裂带中南段晚第四纪活动的主要特征。更多还原

【Abstract】 Global Navigation Satellite System(GNSS)can not only be used for positioning,navigation and timing,but also plays an important role in the crustal deformation monitoring and geophysical inversion.With the development of the Crustal Movement Observation Network of China(CMONOC)and the Continuously Operating Reference Stations(CORS),we could utilize GNSS observation data to achieve higher-precision inversion of regional surface deformation and fault characteristics.The research object of this paper is the central and southern segments of the Tanlu fault zone,which crosses multiple tectonic blocks from north to south with complex internal structural and earthquake disasters occurred frequently since the Quaternary.In the past few decades,several large earthquakes have occurred around the Tanlu fault zone,such as the Wenchuan Ms 8.0 earthquake in 2008 and the Tohoku-oki Mw 9.0 earthquake of Japan in 2011.Therefore,the kinematic properties of the Tanlu fault zone may be affected by the far-field postseismic deformation of these earthquakes.There is a lack of studies on crustal deformation and strain accumulation in the region,and the seismic risk is unknown in this densely populated area.The work of this paper includes three parts.First,use the observation data of AHCORS to obtain a high-precision velocity field under the Eurasian frame,and then combined with the public CMONOC velocity field data.Second,the multi-scale spherical wavelet and least-squares collocation method are used to calculate the strain rates on the central and southern segments of the Tanlu fault zone.Through the results of strain rates of principal strain rates,dilatation rates and maximum shear strain rates,the distribution characteristics in local areas are discussed.Third,based on velocity field vector data,negative dislocation model is used to invert the distribution of locking degree,locking depth and slip rate deficit of the central and southern segment of the Tanlu fault zone,so as to analyze and evaluate the seismic risk in the study area.The main research results of this paper are as follows:(1)Use GAMIT/GLOBK software to solve the observed data of AHCORS in recent 6 years from January 1,2013 to June 30,2018.The coordinate time series and velocity field under the International Terrestrial Reference Frame 2008(ITRF2008)are obtained.In order to more accurately analyze the motion characteristics of the region,the velocity field under the ITRF2008 framework is converted to the Eurasian framework.The results show that the speed of AHCORS reference station under the Eurasian framework mainly moves to the east by south direction.According to the results of velocity profiles,the velocity parallel to the profile is-0.76～-0.35 mm/a,and the velocity perpendicular to the profile is-0.44～-0.29 mm/a.The motion characteristics of the central and southern segment of Tanlu fault zone are dextral and compression.(2)The multi-scale spherical wavelet and the least square collocation method are used to calculate the strain parameters of the central and southern segments of Tanlu fault zone.The results show that the least square collocation method shows that the principal strain rate near the Weifang-Tancheng section on the central and southern segments of the Tanlu fault zone is almost zero;The Tancheng-Jiashan section is the high value area of the principal strain rate.Bounded by the Tanlu fault zone,the west side is characterized by near E-W and N-S stretching,and the east side is characterized by NE-SE or NW-SE stretching;The principal strain rate of Jiashan-Tongcheng section is relatively small,and its east side is characterized by near E-W tension,and its west side is dominated by near N-S compression.The results of principal strain rate of multi-scale spherical wavelet method are similar.For the dilatation rates,the least square collocation method shows that the maximum value appears in the west of Tancheng-Jiashan section,which is in the state of expansion with a size of 3.78×10;~8/(6.The results of multi-scale spherical wavelet can reflect the characteristics of strain accumulation in a smaller region.In the west of Tancheng-Jiashan section,the north is in the state of compression,while the south is in the state of expansion.For the maximum shear strain rate,the least square collocation method shows that it on the central and southern segments of the Tanlu fault zone is smaller than that on both sides of the Tancheng-Jiashan section and the east of Tongcheng.The results of multi-scale spherical wavelet method also show approximate characteristics,but the size is slightly larger than that of least square collocation method.(3)The AHCORS velocity field under the Eurasian framework is fused with the CMONOC velocity field to obtain a"new"velocity field.Taking the GPS velocity field vector data as constraints,the activity characteristics of the central and southern segment of the Tanlu fault zone are inverted by the negative dislocation model.The results show that compared with Tancheng-Jiashan and Jiashan-Tongcheng segments on the central and southern segment of Tanlu fault zone,Weifang-Tancheng segment has higher locking degree,deeper locking depth and higher slip rate deficit,which means that strain accumulation is more likely to occur in this segment.In general,the strain accumulation rate in the Weifang-Tancheng segment on the central and southern segments of the Tanlu fault zone is faster,and the possibility of earthquake risk is greater.In general,the recurrence interval of long-period large earthquakes is the main feature of the late Quaternary activity on the central and southern segments of the Tanlu fault zone.更多还原