芦山地震前后川滇地区地壳水平形变特征研究

为获取芦山地震前后川滇地区地壳的形变特征,利用陆态网2009—2013年和2014—2016年两期全球卫星导航系统(GNSS)水平速度场资料分别计算并对比分析了地震发生前后主应变率场、最大剪应变率场、面膨胀率场及基线长度的变化情况。结果显示芦山地震之前龙门山断裂带主要以压缩应变为主,面压缩应变和最大剪应变均处于高值区,震后能量部分释放,压缩形变程度减弱,但其西南方向的安宁河断裂带和鲜水河断裂带南段出现明显的压缩应变高值区,同时南汀河断裂带附近也呈现较明显的压缩应变。岷江断裂带附近区域的压缩应变虽然减弱,但仍然没有改变它的应变状态,这可能促使了2017年九寨沟Ms7.0地震的发生。     

利用局域欧拉矢量法建立CGCS2000速度场模型

提出了利用局域欧拉矢量法建立CGCS2000速度场模型,并且给出确定局部区域点的方法——移动窗口法。首先利用GAMIT／GLOBK软件对“中国地壳运动观测网络工程”（简称“网络工程”）约1070个参考站近10a观测数据重新处理,再进行一元线性回归分析,获得该“网络工程”的速度场;然后利用提出的局域欧拉矢量法对速度场建模,给出了确定局部区域点的移动窗口法的基本原理和具体步骤,并且通过计算对这种方法确定的速度精度进行了分析和比较;最后利用该模型获得CGCS2000其余约1400个参考站的速度。     

Research on the deformations in Qinghai-Tibet plateau and its margins by inverting seismic moment tensors and GPS velocities

We have determined approximate average rates of deformation in the Qinghai-Tibet plateau and its margins from the GPS data for last 10 years and the moment tensors from earthquakes between 1900 and 1999. We also determined the strain rate (seismic strain rate) associated with the seismic deformation using 254Mω≥5.0 earthquakes, and estimated the shortening and extension rates for every block in the area as well. We also estimated the strain rate (geodetic strain rate) by 80 GPS sites’ velocity vectors and analyzed characteristic of kinematics by two kinds of strain rates and discussed earthquake potential in the area. As a result, the deformation rates from seismic moment tensors and from GPS velocities are basically agreed with each other. It is feasible to analyze seismic risk by comparing geodetic strain rate with seismic strain rate based on the opinion that strain energy will be released through earthquake. It is concluded that there is no strong earthquake potential (>M7) in the Qinghai-Tibet plateau and its margins, but there is earthquake potential (>M5) in middle Tibet in a few years.     

Radar interferometry time series analysis of Mashhad subsidence

A large agricultural area located in 20 km north of the city of Mashhad in the north-east of Iran is subject to land subsidence. The subsidence rate was achieved in a couple of sparse points by precise leveling between 1995 and 2005, and continuous GPS measurements obtained from 2005 to 2006. In order to study the temporal behavior of the deformation in high spatial resolution, the small baseline subset (SBAS) algorithm was used to generate the interferometric SAR time series analysis. Time series analysis was performed using 19 interferograms calculated from 12 ENVISAT ASAR data spanning between 2003 and 2006. The time series results exhibited that the area is subsiding continuously without a significant seasonal effect. Mean LOS deformation velocity map obtained from time series analysis demonstrated a considerable subsidence rate up to 24 (cm/yr). In order to evaluate the time series analysis results, continuous GPS measurements as a geodetic approach were applied. The comparisons showed a great agreement between interferometry results and geodetic technique. Moreover, the information of various piezometric wells distributed in the area corresponding to 1995 to 2005 showed a significant decline in water table up to 20 meters. The correlation between the piezometric information and the surface deformation at well’s locations showed that the subsidence occurrence in Mashhad is due to the excess groundwater withdrawal.     

中国大陆主要块体现今变形状态的反演研究

本文利用中国大陆的GPS运动速度场,研究了其中的7个亚板块和14个构造块体的变形状态,并做了动力学解释。研究中,构造了一种运动-变形模型来提取观测数据中的变形信息。结果表明:南北构造带东西两侧应变状态表现出显著的差异,西部各亚板块或块体的主应变量值从约4.5×10-8.a-1到约1.3×10-8.a-1,东部则从约3.0×10-.8a-1到约0.4×10-.8a-1,表明东西两部应变量值有较大的落差,并且主压应变方向从西部的北北东向逐步转到东部北东东向。南北构造带表现为其不同段落的各块体的变形趋势和量级都有显著不同。川滇块体是东部与西部的结合部位,变形量较大,主压应变为3.4×10-8.a-1,反映了印度板块向北的推挤在川滇块体造成了较大变形。中国北部地区向东西两个方向运动,塔里木块体、准噶尔块体、天山块体向西,柴达木-祁连山块体、阿拉善块体向东。这种推挤力和太平洋板块阻碍、遏制作用,造成了华北块体、鄂尔多斯块体以拉张为主的应变和逆时针旋转。     

Research on the deformations in Qinghai-Tibet plateau and its margins by inverting seismic moment tensors and GPS velocities

We have determined approximate average rates of deformation in the Qinghai-Tibet plateau and its margins from the GPS data for last 10 years and the moment tensors from earthquakes between 1900 and 1999.We also determined the strain rate (seismic strain rate) associated with the seismic deformation using 254 Mw≥5.0 earthquakes,and estimated the shortening and extension rates for every block in the area as well.We also estimated the strain rate (geodetic strain rate)by 80 GPS sites' velocity vectors and analyzed characteristic of kinematics by two kinds of strain rates and discussed earthquake potential in the area.As a result,the deformation rates from seismic moment tensors and from GPS velocities are basically agreed with each other.It is feasible to analyze seismic risk by comparing geodetic strain rate with seismic strain rate based on the opinion that strain energy will be released through earthquake.It is concluded that there is no strong earthquake potential (＞M7) in the Qinghai-Tibet plateau and its margins,but there is earthquake potential (＞M5) in middle Tibet in a few years.     

广西区域现今地壳运动与应变的GPS监测分析

利用GAMIT/GLOBK软件分析了1998-2010年间多期GPS观测数据,获得了ITRF2005框架下广西区域现今地壳运动三维速度场和应变场参数,并对区域形变场和现今构造运动动力学机制进行了初步讨论。GPS监测结果显示:广西区域现今地壳运动随华南块体作南东东方向的逆时针构造运动,ITRF2005框架下水平方向平均速率为33.49 mm/a,优势方向为N 109.3° E;垂直方向平均速率为+1.30 mm/a,整体趋势是自桂东向桂西方向垂向速率逐步增加。现今应变状态以N 127.3°±4.8° E挤压为主,最大主压应变率-2.7±0.5×10^-9/a;兼有N 37.3°±4.8° E方向的拉张作用,最大主张应变率1.8±0.2×10^-9/a。本文研究结果为描述广西区域现今地壳运动提供了一个更加精细的三维速度场。     

空间技术观测数据对全球七大板块运动参数的精化

采用截止到2003年GPS观测数据和1997年的VLBI观测数据,利用它们的站速度信息,组合解算完全基于空间技术的板块运动参数;通过对站速度残差的精化分析,得出更加稳健的现时板块运动参数;并通过反复试算得出稳定台站的选取以及台站的分布对板块运动欧拉极有很大的影响。     

华北地区应变率及其精度评定

华北地区的形变信息较弱,GPS获得的地壳长趋势的构造变化信息是否可以反映华北地区的形变信息尚未有人讨论。本文利用多面函数双调和法对华北地区COMNOC的GPS速度场进行建模、滤波,计算了华北地区的应变率,进一步通过误差传播率评估了应变率的精度。综合分析表明,多面函数双调和法计算得到的应变率具有很高的精度,精度结果分布与实测数据相符,实测点越多的区域,应变率的精度越高。     

利用局域复测GPS网研究中国大陆块体现今地壳运动速度场

利用1992年以来我国进行的6项不同规模高精度GPS地壳监测网的资料，采用统一的数据处理策略，重新进行了数据处理，并统一进行了平差，归算到相同的ITRF97坐标框架基准之下，获得了中国前覆最广、测站最多的一个较为完整的、框架统一的GPS地壳运动图像和速度场，并对结果作了初步的地学解释。     

喜马拉雅块体现今运动学特征的地震矩张量反演分析

利用地震矩张量反演计算了喜马拉雅块体地震主应变率，应变率主方向以及变形速率，探讨了喜马拉雅块体现了形变特征，并与GPS形变监测结果以及地震结果进行了比较分析。地震矩张量反演结果表明，喜马拉雅块体不仅有南北向的压缩变形，而且有显著的东西向拉张运动，其变形量级与GPS形变监测结果，地质资料得出的结果基本一致，与珠峰地区GPS计算结果获得的该地区的应变趋势基本一致。     

基于GPS观测数据的云南地区地壳形变特征研究

利用1999~2013年间多期GPS观测数据,将云南地区分为5个活动块体,研究区域现今水平运动特征、应变特征以及各块体的运动特征,反演主要活动断裂带的走滑速率。结果表明,区域水平运动具有北强南弱的特征,小江断裂带、红河断裂带对云南地区构造活动具有明显控制作用,改变了断裂带两侧的运动特征;区域应变具有明显的差异,西部以拉张应变为主,东部小江断裂带周边地区拉张和挤压应变均衡且为强应变区,滇东地区应变较小;各块体运动方向与速率存在差异,滇东块体为逆时针旋转,其余块体顺时针旋转;基于块体模型反演的主要断裂带的走滑速率与地质方法获取的走滑速率具有较好的一致性。     

融合分布式目标的小基线集干涉测量方法应用

针对在地理国情监测项目中遇到的时间序列InSAR技术获取的地表形变结果存在空间采样率不足的现状,该文以传统小基线集干涉测量方法为基础,融合分布式目标提取地表缓慢形变信息。以TerraSAR-X星载SAR SLC影像为数据源,对融合后的方法进行验证,获取了研究区域时间序列地表平均形变速率。结果表明,融合分布式目标的小基线集算法可以有效提高监测区域地表形变信息的获取,在非城市地区及传统方法不能提取高相干稳定点目标的区域克服了原有方法的缺点,表现出了很好的适用性。     

基于CGCS2000的中国地壳水平运动速度场模型研究

首先介绍通过数据处理获取CGCS 2000(中国大地坐标系统2000)下点位坐标和速度场的方法,其次研究分析在CGCS 2000下建立满足中国大陆区域无整体旋转条件的中国大陆板块位移基准方法,计算得到的CGCS 2000下中国大陆区域的欧拉角速度是0.2997(°)/Ma,旋转极的位置为(64.77°N,94.093°E),最后利用计算获取的CGCS 2000下的国家高精度GPS网的坐标和速度值,采用有限元插值方法建立中国大陆区域地壳运动速度场模型,并初步分析CGCS2000下的中国大陆地壳运动整体趋势.通过本文的研究可以进一步维护和精化中国CGCS 2000的稳定性、动态性和精确性,也可对CGCS 2000坐标参考框架下的中国区域地壳运动特征的研究提供科学方法和高时空分辨率的基础数据.

Abstract：

Firstly, the processing strategy of obtaining the coordinate and velocity based on the CGCS 2000 (Chinese geocentric 3D coordinate system)is introduced. Secondly, a new plates displacement reference frame of Chinese mainland subjected to the regional No-Net-Rotation (NNR) conditions is researched, The results inferred the position of the Euler rotation pole of the Chinese mainland plates is (64, 77°N,94.093°E) and its rate is 0. 299 7(°)/Ma based on the CGCS 2000. Finally, Crustal movement velocity field of Chinese mainland are inferred through the precise result of CORS and national GPS network, and the model of crustal deformation velocity field has been established based on the adoptions of finite element interpolation method. On which, the regional crustal deformation characters of China mainland have been proximately analyzed. Based on the study of this paper, the precision, dynamics and reliability of CGCS 2000 would be further renewed and maintained, further more the basic data with high spatial-temporal resolution and scientific methods are referred to study characteristics of Chinese mainland crustal movement.     

用大地测量方法分析三江地区运动态势

本文利用绝对重力测量、重力场、形变和GPS测量资料浅析该地区水平和垂直形变态势。用5′×5′实测资料编绘了布格异常图,编绘了1975～1997年川西垂直形变速率图及多年绝对重力变化图等。经分析研究有以下初步结果：1.重力异常等值线展布形态与构造格局一致,由北向南倾。此外,还发现了一条东西向异常梯级带,估计是一条未被证实的东西向断层,且是一条与构造活动密切相关的断层,应予以关注;2.布格异常等值线的舌状态势反映了川滇菱形断块南南东向楔入的运动状态。另外断层若是水平错断,则在布格异常图上没有梯级带表现;3.研究结果表明,川西地区的垂直形变是以隆升为主的继承性运动,北部山区的隆升速率大,由北向南,垂直形变速率绝对值减小。滇西的垂直形变速率与绝对重力的时间变化率基本呈逆相关。洱源、丽江位于隆升速率大的地区,也是绝对重力变化负值大的点,下关则位于垂直形变速率平缓的零值附近,它的绝对重力变化值也最小。     

川滇地区近期地壳变形动态特征研究

基于1999年以来的GPS观测数据,重点分析了川滇地区近期的变形特征,计算给出了该区域主要断裂带的滑动速率,并结合GPS剖面初步识别了断裂带所处的孕震阶段。结果表明,红河断裂带始终处于弱形变区域,值得进一步关注;汶川地震后,由于研究区域应力场的调整和应变的重新分配,使得安宁河断裂带的活动变化较小,逐步趋缓,走滑分量存在明显趋缓现象,并且安宁河断裂带的闭锁深度在一定程度上有所增加;小江断裂带的走滑分量存在明显趋缓现象,显示存在强闭锁现象,小江断裂带平行于断层方向GPS速度剖面显示断裂带两侧变形平缓且变形范围较大;昭通、莲峰断裂的挤压和剪切变形积累均存在弱化现象,可能预示该区域挤压应变积累背景较高。     

EPC: Matlab software to estimate Euler pole parameters

The estimation of Euler pole parameters has always been an important issue in global tectonics and geodynamics studies. In addition, the increasing number of permanent GPS stations and the ease of access to their data, along with advances in computers, promise new methods and tools for the estimation and the quantitative analysis of Euler pole parameters. Therefore, we developed the Euler pole calculator software using a set of mathematical algorithms based on the model of tectonic plate motion on a spherical surface. The software is able to calculate the expected velocities for any points located on the earth’s surface given the relevant Euler pole parameters and to estimate the Euler pole parameters given the observed velocities of a set of sites located on the same tectonic plate. Mathematical algorithms and functions of the software are explained in detail.     

Contemporary crustal velocity field in Alpine Mediterranean area of Italy from new geodetic data

A new crustal velocity field for the Alpine Mediterranean area was determined by using a time series spanning 6.5 years of 113 global navigation satellite system (GNSS) permanent stations. This area is characterized by a complex tectonic setting driven by the interaction of Eurasian and African plates. The processing was performed by using a state-of-the-art absolute antenna phase center correction model and by using recomputed precise International GNSS Service orbits, available since April 2014. Thus, a new and more accurate tropospheric mapping function for geodetic applications was adopted. Results provide a new detailed map of the kinematics throughout the entire study area. In some area of the Italian peninsula, such as in the central Apennines, the velocity vector orientation appears rotated with respect to previous results. These discrepancies suggest that the geodynamic setting of this sector of Mediterranean area should be revised in accordance with these new results.     

基于球面最小二乘配置的福建省地壳水平形变研究

利用GPS实测数据解算区域地壳应变率分布是现今地壳水平形变研究的一个重要手段。本文研究采用基于球坐标的最小二乘配置应变率计算公式,结合GPS实测速度场解算福建省东南沿海及其邻近区域应变率场。结果显示,福建东南沿海地壳形变主要受到来自印度板块与菲律宾板块对欧亚大陆的共同作用。区内主压应变率趋势强于主张应变率趋势。以九龙江断裂为界,以北地区地壳形变特征较为一致,断裂以南地区,自北东向西南,区域地壳形变逐渐变化,呈现离散化、多样化的特征。     

HNGICS站ITRF2014框架下三维变化分析

针对河南省内地表沉降问题,利用河南省地质信息连续采集运行系统(HNGICS)分析全省域内地表形变,对比时间基线为10 a的HNGICS基准站ITRF2014框架下三维坐标,获得河南省内三维速度场,分析河南省内地表形变规律与地质环境相关。结果表明:河南省内整体平面位移变化较小,平面变化10 mm以内的基准站16个,在10～20 mm之间的站点15个,整体趋势表现为由西向东,南部水平位移优势方向为东偏北方向30.7°,平均运动速率为0.87 mm/a;北部平原水平位移优势方向为东偏南方向82.6°,平均运动速率为1.6 mm/a,省域内地表存在明显的相对运动;竖直方向上,东部平原地区平均沉降速率为11.0 mm/a,山区平均沉降速率为1.4 mm/a,山区沉降速率远小于平原地区。