Abstract
We investigated decaying post-seismic deformation observed on the Korean Peninsula associated with the 2011 Mw 9.0 Tohoku-Oki earthquake using Global Navigation Satellite System (GNSS). The GNSS velocity vectors were estimated in five periods from 2005 to 2019. A co-seismic offset of the Korean Peninsula caused by the 2011 earthquake was inversely proportional to epicentral distances. According to the temporal variations of two components (magnitude and direction) of the GNSS velocity vector with the epicentral distance, the difference between the eastern and western regions for the two components becomes smaller over time. For approximately nine years after the 2011 event, the direction for the crustal movement in South Korea showed a recovery pattern returning to the pre-earthquake motion. In addition, the recovery patterns of the crustal movement were observed differently with the regional geologic structure (e.g., the crustal thickness) and each period. Our estimates of the decay in post-seismic deformation of the Korean Peninsula suggest that post-seismic relaxation will be complete within 5–20 years after the 2011 earthquake. The results suggest that the crustal movement on the Korean Peninsula is gradually recovering to its pre-earthquake motion.
Highlights
Many earthquakes occur somewhere on Earth every day
Global Navigation Satellite System (GNSS) data with a sampling interval of 30s were processed in the International GNSS Service (IGS) realization of the reference frame International Terrestrial Reference Frame (ITRF) 2014 using a double-difference method in the Bernese 5.2 software [22]
Before the 2011 Tohoku-Oki earthquake, the crust of the Korean Peninsula moved at an average rate of approximately 30 mm/year in the direction of 119 degrees
Summary
Many earthquakes occur somewhere on Earth every day. Most earthquakes are so weak that they rarely cause ground displacements, but some large earthquakes produce significant crustal deformation over large distances. Studies of major earthquakes with magnitudes exceeding 7.0 play a key role in improved understanding of crustal deformation, including co-seismic and post-seismic effects [1]. Many studies have been conducted on major earthquakes to investigate earthquake-induced crustal deformation and evaluate the geodynamic effects [2,3,4]. Megathrust earthquakes create considerable co-seismic displacements, and post-seismic deformation over a long duration. Ozawa et al [4] reported that the onshore co-seismic displacement nearest to the epicenter of the Tohoku-Oki earthquake reached approximately 5.3 m. Tobita [7] suggested that there has been a continuous increase in the contribution of viscoelastic relaxation to post-seismic deformation in eastern
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