The 2011 Tohoku-Oki earthquake's influence on the Asian plates and Korean geodetic network

초록

In this study, we analyzed the effects of seismic displacements due to the megathrust earthquake occurred near Tohoku-Oki area on 11 Mar. 2011 with M(w)9.0 magnitude in the context of evaluation of position change by the earthquake on the Asian and Korean GPS permanent stations. For this, two weeks GPS data observed around the event of Tohoku-Oki earthquake (4 Mar-18 Mar. 2011) were obtained from 55 GPS permanent stations in the vicinity of epicenter (Korea, Japan, Russia, China and Taiwan) and 284 IGS global stations. All available GPS data were processed and adjusted by GAMIT/GLOBK software to estimate the co-seismic horizontal displacements at each station. As the results of GPS analysis, the co-seismic displacements by Tohoku-Oki earthquake were clearly revealed in the GPS stations of Asian region, Japan and its neighboring countries, and even the change of horizontal position of GPS station (WUHN in China) which was about 2702 km away from the epicenter. Also, we performed the elastic deformation analysis using the deformation lengths of baselines between Korean UPS stations estimated from GAMIT/GLOBK analysis, in order to analyze the effects of Tohoku-Oki earthquake more precisely on the Korea geodetic network. Most GPS baselines of Korean geodetic network expanded in the direction of epicenter, whereas those perpendiculars to the direction of epicenter contracted. The size of maximum shear strain rate calculated during the event of Tohoku-Oki earthquake is 7 times greater than annual result of the Korean geodetic network. In conclusion, it was found that the Tohoku-Oki earthquake had resulted in the horizontal displacements, ranging from 57.7 mm to 14.5 mm in Korea. So, these irregular displacements caused the elastic deformations in Korean geodetic network and may cause a maximum error of 20 mm in GPS geodetic positioning results without updating the Korean geodetic network.

키워드