[S-GD01] Geodesy and Global Geodetic Observing System

[SGD01-P07] Investigation of interpolation method for estimation of Surface Deformation model

*Tomoaki Furuya¹, Tomokazu Kobayashi¹, Hiroyuki Nakagawa¹, Koji Matsuo¹, Saho Matsumoto¹, Tatsuya Yamashita¹ (1.Geospatial Information Authority of Japan)

Keywords:GNSS, GNSS CORS, Crustal Deformation model

GSI introduced semi-dynamic correction in the field of survey in 2010 (Hiyama et al., 2010) and provided POS2JGD extending it for precise positioning in 2020, to reduce the effect of the strain due to steady-state crustal deformations such as caused by plate motion. In the corrections, the effect of the strain that has accumulated from the reference epoch to the current epoch is corrected by using the crustal deformation model constructed with the use of the daily coordinates of about 1,300 GNSS Continuously Operating Reference Stations (CORSs). Its deformation values at grid points with the spacing of about 5 km are obtained by interpolation of the differences of the coordinates between the current epoch and the reference epoch at CORSs by means of Kriging method. In order to accurately correct the effect of the strain accumulating over time, it is updated every 3 months in POS2JGD. However, because technical development enables us to obtain more accurate coordinates easily, the crustal deformation model is needed in order to use the coordinates obtained by highly accurate satellite positioning with geospatial information based on the geodetic datum such as to match them to maps. The present model cannot accurately reproduce the crustal deformation with large velocity and its change including the early post-seismic deformation observed after the 2011 Tohoku-oki earthquake.
In this study, we estimated time-series models from the daily coordinates of the GNSS CORS with reference to Tobita (2016) and Fujiwara et al. (2022), and examined a method to spatially interpolate the amount of variation for GNSS CORS, to develop a crustal deformation model that can reproduce crustal deformation including post-seismic deformation more accurately. In this presentation, we will report the results of the evaluation.

Reference:
Hiyama, Y., Y.Morishita, H. Yamao, T. Yutsudo, K. Ochi and M. Iwata (2010): Towards the Introduction of Semi-Dynamic Correction, Bulletin of the GSI, 120, 55–61. (in Japanese)
Tobita, M. (2016): Combined logarithmic and exponential function model for fitting postseismic GNSS time series after 2011 Tohoku-Oki earthquake, Earth Planets and Space, 68:41, doi:10.1186/s40623-016-0422-4.
Fujiwara S, Tobita M, Ozawa S (2022): Spatiotemporal functional modeling of postseismic deformations after the 2011 Tohoku-Oki earthquake, Earth Planets and Space, 74:13, doi:10.1186/s40623-021-01568-0.