Characterizing the Seasonal Crustal Motion in Tianshan Area Using GPS, GRACE and Surface Loading Models

Yunlong Wu,Qian Zhao,Weiwei Wu,Bao Zhang

doi:10.3390/rs9121303

Abstract

Complex tectonic and non-tectonic movements exist in the Tianshan area. However, we have not acquired good knowledge of such movements yet. In this study, we combine Global Positioning System (GPS), the Gravity Recovery and Climate Experiment (GRACE) and Surface Loading Models (SLMs) data to study the seasonal vertical crustal displacements in the Tianshan area. The results show that all three datasets exhibit significant annual variations at all 26 local GPS stations. Correlation coefficients higher than 0.8 between the GRACE and GPS data were observed at 85% of the stations, and it became 92% when comparing GPS and SLMs. The Weighted Root Mean Squares (WRMS) reductions were 41% and 47% after removing the annual displacements of GRACE and SLMs from the GPS time series, respectively. The consistency between the GPS and SLMs data was higher than that between the GPS and GRACE data, which is mainly due to the dominant position of atmospheric loading in the study area. For the abnormal station XJYN (43°N, 81°E), the GPS time series showed an abnormal uplift from early 2013 to early 2015, but this not shown in the GRACE and SLMs results. We attribute this discrepancy to groundwater variations, which are not resolvable by GRACE and SLMs for small-scale regions.

Highlights

Under the enormous northward extrusion dynamics of the Indian Plate, the crust in the Tianshan region has been subject to intense compression and uplift, resulting in the formation of a large-scale intraplate regenerated orogenic belt [1,2]
It can be seen that the Global Positioning System (GPS), Gravity Recovery and Climate Experiment (GRACE) and Surface Loading Models (SLMs) vertical time series show clear significant seasonal signals
The results suggest that a slight systematic difference exists between the GPS and GRACE/SLMs results for both amplitude and phase

Summary

Introduction

Under the enormous northward extrusion dynamics of the Indian Plate, the crust in the Tianshan region has been subject to intense compression and uplift, resulting in the formation of a large-scale intraplate regenerated orogenic belt [1,2]. A large number of observations has been obtained to provide important information for accurate determination of the three-dimensional velocity field of the crust in Tianshan area, as well as for studying regional crustal movements and tectonic activities [3,4,5,6]. In addition to tectonic deformation, the vertical deformations of the surface observed by GPS include significant non-tectonic seasonal variations, for which it is difficult to distinguish the sources of these signals. The seasonal vertical deformation, caused by environmental mass redistribution, can be observed through some other geodetic techniques, such as the Gravity Recovery. The cr2uosfta13l vertical deformation obtained by GRACE can be used to exclude the non-tectonic impact caused by laannddCwliamteartsetoErxapgeerimn ethnet (GGPRSArCesEu)ltasn. Rmal stations to obtain important information for studying regional environmental loading changes Fpuortahnetrminoforer,mSaintigounlfaorrSsptuecdtyruinmg rAengaiolynsailse(nSvSAiro) nwmaesnutsaeldlotaodaingalcyhzaenagbenso. rmal stations to obtain important information for studying regional environmental loading changes

Results

Discussion

Conclusion