Performance analysis of NGS CORS site for precise measurement of seismic activities

Abstract

The National Geodetic Survey (NGS) CORS sites deviate from their assigned position coordinates due to seismic activities. A rigorous computation is required to maintain position coordinates of NGS CORS network. On 23rd of June 2014 an earthquake of magnitude 7.9 strongly hit the Aleutian Islands. This earthquake deviated Adak AB21 CORS site from its assigned NAD_83 (EPOCH 2010) position coordinates. NGS revised position of this CORS site last time in December 2012 by using 57 days of data. As the position coordinates of this CORS site are not revised after 2012, the present GPS data shows a significant deviation of this CORS site from published position coordinates. This substantial deviation is due to Aleutian Islands earthquake and the North American tectonic plate movement. In this paper précised computations of all inter seismic, co seismic, and post seismic activities associated with Aleutian Islands earthquake are achieved to revise Adak AB21 CORS position coordinates. This paper includes precise measurement of all seismic deviations due to 23rd June 2014 Aleutian Islands earthquake, by using AB21 CORS site observation data. For this purpose 24 hr GPS observation data recorded by AB21 CORS site on 23rd of June 2014 is post processed with RTKLIB software by configuring RTKPOST. 60 days post seismic data recorded by the same CORS site is used to compute the deviation from its assigned NAD_83 (2011) position coordinates. This GPS observation data is post processed by Online Position User Service (OPUS).