2:30 PM - 2:45 PM
[SGD02-04] Investigation of Crustal Deformation model using daily coordinates of GNSS CORS
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.
This study uses logarithmic and exponential functions to represent post-seismic deformation (Tobita, 2016), to develop a crustal deformation model that can reproduce crustal deformation including post-seismic deformation more accurately. However, simply using the daily coordinates of the GNSS CORS to estimate reasonable time constants and coefficients for the functions is affected by outliers in the daily coordinates caused by changes of the observation environment or failure of the observation equipment. Therefore, a method to consider the standard deviation as weight when estimating time constants is examined. The standard deviation is calculated from the epoch-by-epoch coordinate of the GNSS CORS by precise point positioning. 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.
This study uses logarithmic and exponential functions to represent post-seismic deformation (Tobita, 2016), to develop a crustal deformation model that can reproduce crustal deformation including post-seismic deformation more accurately. However, simply using the daily coordinates of the GNSS CORS to estimate reasonable time constants and coefficients for the functions is affected by outliers in the daily coordinates caused by changes of the observation environment or failure of the observation equipment. Therefore, a method to consider the standard deviation as weight when estimating time constants is examined. The standard deviation is calculated from the epoch-by-epoch coordinate of the GNSS CORS by precise point positioning. 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.