Seasonal Hydrological Loading in Southern Tibet Detected by Joint Analysis of GPS and GRACE

被引:32
作者
Zou, Rong [1 ,2 ]
Wang, Qi [1 ]
Freymueller, Jeffrey T. [3 ]
Poutanen, Markku [2 ]
Cao, Xuelian [1 ]
Zhang, Caihong [4 ,5 ]
Yang, Shaomin [4 ,5 ]
He, Ping [1 ]
机构
[1] China Univ Geosci, Inst Geophys & Geomat, Hubei Subsurface Multiscale Imaging Key Lab, Wuhan 430074, Peoples R China
[2] Finnish Geospatial Res Inst FGI, Masala 02430, Finland
[3] Univ Alaska Fairbanks, Inst Geophys, Fairbanks, AK 99775 USA
[4] China Earthquake Adm, Inst Seismol, Wuhan 430071, Peoples R China
[5] Hubei Earthquake Adm, Wuhan 430071, Peoples R China
基金
中国国家自然科学基金;
关键词
seasonal variations; GRACE; GPS; vertical deformation; horizontal deformation; MASS VARIATIONS; VELOCITY-FIELD; DEFORMATION; EARTH; CHINA; DISPLACEMENTS; VARIABILITY; PLATEAU; STRAIN; DRIVEN;
D O I
10.3390/s151229815
中图分类号
O65 [分析化学];
学科分类号
070302 ; 081704 ;
摘要
In southern Tibet, ongoing vertical and horizontal motions due to the collision between India and Eurasia are monitored by large numbers of global positioning system (GPS) continuous and campaign sites installed in the past decade. Displacements measured by GPS usually include tectonic deformation as well as non-tectonic, time-dependent signals. To estimate the regional long-term tectonic deformation using GPS more precisely, seasonal elastic deformation signals associated with surface loading must be removed from the observations. In this study, we focus on seasonal variation in vertical and horizontal motions of southern Tibet by performing a joint analysis of GRACE (Gravity Recovery and Climate Experiment) and GPS data, not only using continuous sites but also GPS campaign-mode sites. We found that the GPS-observed and GRACE-modeled seasonal oscillations are in good agreements, and a seasonal displacement model demonstrates that the main reason for seasonal variations in southern Tibet is from the summer monsoon and its precipitation. The biggest loading appears from July to August in the summer season. Vertical deformations observed by GPS and modeled by GRACE are two to three times larger than horizontal oscillations, and the north components demonstrate larger amplitudes than the east components. We corrected the GPS position time series using the GRACE-modeled seasonal variations, which gives significant reductions in the misfit and weighted root-mean-squares (WRMS). Misfit (chi(2) divided by degree of freedom) reductions for campaign sites range between 20% and 56% for the vertical component, and are much smaller for the horizontal components. Moreover, time series of continuous GPS (cGPS) sites near the 2015 Nepal earthquakes must be corrected using appropriate models of seasonal loading for analyzing postseismic deformation to avoid biasing estimates of the postseismic relaxation.
引用
收藏
页码:30525 / 30538
页数:14
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