5:15 PM - 6:30 PM
[SGD01-P04] Evaluation and Examination of Post Seismic Deformation Model in Maintenance of Geodetic Reference Coordinate System
Keywords:post seismic deformation, deformation model, geodetic reference coordinate system
GSI has been participating in multilateral international joint campaigns and observations, such as International VLBI Service for Geodesy and Astrometry (IVS) and International GNSS Service (IGS). Under the cooperation, GSI has been operating VLBI and GNSS stations and providing or analyzing the observation data, and these efforts contribute to development of International geodetic reference system (ITRF). ITRF solution provides station position at a given epoch (2010.0), station velocities of GSI’s VLBI and IGS stations such as Ishioka VLBI station or Tsukuba IGS station, which GSI has been operating. An accurate geodetic reference coordinate system in Japan has been realized with the solution of ITRF.
In ITRF2014 released in January 2016, post seismic deformation (PSD) model was introduced in the solution, in addition to the conventional ITRF products (station positions and velocities, and Earth Orientation Parameters (EOPs)). The PSD model made us to correct the displacement of the positon due to the post seismic deformation of a large-scale earthquake. Especially in Japan, due to the impact of the 2011 off the Pacific coast of Tohoku Earthquake (2011 Tohoku-oki earthquake), displacement on the scale of several tens of centimeters have occurred, and it is necessary to correct them using the PSD model.
Although ITRF2014 solution provides the PSD model as mentioned above, the period of the date used to estimate the model is from January 1st, 2003 to February 7th, 2015. It means that the predicted values estimated with the PSD model is used to correct the displacement caused after the period of the data (February 7th, 2015). The post seismic deformation due to the 2011 Tohoku-oki earthquake continue as of 2021, and there are still some areas where the annual displacement of up to 10cm /year occur in the horizontal direction. At the stations in such areas, which was included in ITRF2014 solutions, it is assumed that the predicted values by the PSD model deviate from the actual values, and it might be difficult to calculate accurate positions of the stations.
In this study, we evaluate the validity of the PSD model of ITRF2014 using the data up to the end of December 2020, and consider the causes of the residuals of the correction with PSD model. In addition, a new PSD model is calculated by referring the estimation method of the model using logarithmic and exponential functions (Tobita (2016)) and the estimation method by Markov chain Monte Carlo methods (MCMC) (Miyazaki (2018)), and evaluate the validity of the model calculated by a method which differs from the method in ITRF2014. In this presentation, we will report the results of the evaluation and discuss the effectivity and limitations of the PSD model in maintenance of the geodetic reference coordinate system.
In ITRF2014 released in January 2016, post seismic deformation (PSD) model was introduced in the solution, in addition to the conventional ITRF products (station positions and velocities, and Earth Orientation Parameters (EOPs)). The PSD model made us to correct the displacement of the positon due to the post seismic deformation of a large-scale earthquake. Especially in Japan, due to the impact of the 2011 off the Pacific coast of Tohoku Earthquake (2011 Tohoku-oki earthquake), displacement on the scale of several tens of centimeters have occurred, and it is necessary to correct them using the PSD model.
Although ITRF2014 solution provides the PSD model as mentioned above, the period of the date used to estimate the model is from January 1st, 2003 to February 7th, 2015. It means that the predicted values estimated with the PSD model is used to correct the displacement caused after the period of the data (February 7th, 2015). The post seismic deformation due to the 2011 Tohoku-oki earthquake continue as of 2021, and there are still some areas where the annual displacement of up to 10cm /year occur in the horizontal direction. At the stations in such areas, which was included in ITRF2014 solutions, it is assumed that the predicted values by the PSD model deviate from the actual values, and it might be difficult to calculate accurate positions of the stations.
In this study, we evaluate the validity of the PSD model of ITRF2014 using the data up to the end of December 2020, and consider the causes of the residuals of the correction with PSD model. In addition, a new PSD model is calculated by referring the estimation method of the model using logarithmic and exponential functions (Tobita (2016)) and the estimation method by Markov chain Monte Carlo methods (MCMC) (Miyazaki (2018)), and evaluate the validity of the model calculated by a method which differs from the method in ITRF2014. In this presentation, we will report the results of the evaluation and discuss the effectivity and limitations of the PSD model in maintenance of the geodetic reference coordinate system.