Seasonal horizontal deformations obtained using GPS and GRACE data: case study of North-East India and Nepal Himalaya

Abstract

The area of NorthEast India and Nepal Himalaya undergoes seasonal deformations due to the variation of surface mass loads induced mainly by annual monsoon precipitation. The present study focuses on comparing seasonal horizontal deformations of the Earth's surface obtained over the area of NorthEast India and Nepal Himalaya using Global Positioning System (GPS) and the corresponding ones obtained from Gravity Recovery and Climate Experiment (GRACE) satellite mission data. Seasonal deformations of the Earth's surface in horizontal components were determined using daily observations from 36 GPS stations located in NorthEast India and Nepal Himalaya and Release-05 GRACE-based Global Geopotential Models (GGMs). The consistency between these seasonal horizontal deformations was investigated using three statistical metrics, namely: the correlation, Weighted Root Mean Square (WRMS) reduction and Nash-Sutcliffe model Efficiency (NSE). The results obtained indicate that at nearly 89% of GPS stations investigated, positive correlation can be determined between seasonal deformations of the Earth's surface in the north component obtained from GPS and the corresponding ones from GRACE data. The percentage of WRMS reductions computed from seasonal horizontal deformations of the Earth's surface obtained using GPS and GRACE data reach ~ 18% and 0.71% in north and east components, respectively. Moreover, we obtain the median value of NSE almost 0.28 for north and − 0.01 for east components. The study finds that seasonal horizontal deformations in the area investigated are controlled by local tectonics, and realizes the need of a realistic Earth model comprising local crustal inhomogeneities and tectonic features for better constraining the surface deformations in this region.

A Review of GNSS/GPS in Hydrogeodesy: Hydrologic Loading Applications and Their Implications for Water Resource Research

“…Most of the studies that have examined hydrologic loading solely using horizontal deformation were located in areas known to have large hydrologic loads (and thus large GNSS‐recorded vertical deformation), namely the Amazon Basin and Southeast Asia (Bettinelli et al., 2008; Chanard et al., 2014; Fu et al., 2013; Ray et al., 2021). However, a few studies have demonstrated the utility of analyzing both horizontal and vertical surface deformation.…”

“…Horizontal movement from hydrologic loading is generally an order of magnitude less than long-term tectonic movement; therefore, horizontal displacements recorded by GNSS are most commonly used to estimate secular crustal velocities to constrain tectonic-plate motion as well as coseismic and post-seismic deformation due to earthquakes ( Ray et al, 2021 ). Furthermore, Borsa et al ( 2014) note the use of vertical-to-horizontal displacement ratios to identify GNSS stations experiencing tectonic or volcanic motion where horizontal motion exceeds vertical motion.…”

“…Horizontal movement from hydrologic loading is generally an order of magnitude less than long‐term tectonic movement; therefore, horizontal displacements recorded by GNSS are most commonly used to estimate secular crustal velocities to constrain tectonic‐plate motion as well as coseismic and post‐seismic deformation due to earthquakes (Ray et al., 2021). Furthermore, Borsa et al.…”

“…Both GNSS and GRACE infer the integrated total water storage within both surface and subsurface reservoirs. These two estimates of water load, although differing in spatial and temporal resolution, tend to be highly correlated (Adusumilli et al., 2019; Argus et al., 2014, 2017; Borsa et al., 2014; Chew & Small, 2014; Davis, 2004; Fu et al., 2012, 2013; Fu & Freymueller, 2012; King et al., 2006; Nahmani et al., 2012; Ouellette et al., 2013; Ray et al., 2021; Steckler et al., 2010; Tesmer et al., 2011; Tregoning et al., 2009).…”