ORIGINAL RESEARCH article
Front. Earth Sci.
Sec. Solid Earth Geophysics
Temporal variations of geoid heights over Kazakhstan from GRACE– FO data and their relation with hydrological changes in the Caspian Sea and seismic activity
Provisionally accepted
Daniya Shoganbekova1,2
Asset Urazaliyev1*
Walyeldeen Godah3Serik Nurakynov1Nailya Zhaksygul1,2Magzhan Kozhakhmetov1- 1Institute of Ionosphere, Almaty, Kazakhstan
- 2International Education Corporation, Almaty, Kazakhstan
- 3Office of Surveyors General, Ministry of Natural Resources, Ontario, Canada
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This study investigates temporal variations of geoid heights (ΔN) across Kazakhstan from 2019 to 2024, utilizing data from the GRACE–FO satellite mission. Additionally, it aims to analyze these ΔN in the context of recent extreme hydrological events and seismic activities in Kazakhstan. ΔN were determined using GRACE–FO–based Global Geopotential Models. Thereafter, they were analyzed using the seasonal decomposition method. The results obtained revealed a distinct seasonal pattern in ΔN, with amplitudes reaching approximately 3.5 mm. Furthermore, the findings indicated a continuous decline of geoid heights within 2019–2022, with a rate of up to –1.57 mm yr-1 along the Caspian Sea coast. In 2024, significant mass anomalies associated with seismic and hydrological events halted this decline in geoid heights. Moreover, a strong correlation (i.e. correlation coefficient of 0.91) was observed between ΔN and changes in the water levels of the Caspian Sea. Additionally, a preliminary comparison between ellipsoidal height changes from five GPS stations within the study area and ΔN from GRACE–FO data reveals an inverse seasonal pattern, confirming GRACE–FO’s effectiveness in capturing regional mass–related geoid variations in Kazakhstan. Overall, this study demonstrates the capability of satellite gravimetry in monitoring Earth's dynamic mass redistribution in Kazakhstan and provides essential insights for geodetic infrastructure, hazard forecasting, and climate impact assessments in the region. It would also contribute fundamentally to addressing international geodetic challenges, e.g. the realization of the International Height Reference Frame considering the time–varying of the Earth’s gravity field in Central Asia.
Keywords: Geoid heights, GRACE–FO, Seasonal variations, long–term variations, Seismic activity, Extreme hydrological events
Received: 09 Jul 2025; Accepted: 29 Oct 2025.
Copyright: © 2025 Shoganbekova, Urazaliyev, Godah, Nurakynov, Zhaksygul and Kozhakhmetov. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Asset Urazaliyev, a.urazaliyev@ionos.kz
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