Does the Southern Korean Peninsula belong to the Amurian plate? GPS observations

Abstract

The Amurian plate (AM) in Northeast Asia plays a particularly important role in the estimation of surrounding crustal movements and interpretation of seismic activities, especially in southwest Japan. However, the existence of the Amurian plate and the location of the southern boundary remain controversial. Due to insufficient data, the southern boundary is not well known and often assumed to cross the Southern Korean Peninsula. Therefore, this area is critical to further accurately define the Amurian plate geometry. The existing permanent Korean GPS network (KGN) with more than 45 GPS sites plays a key role to discriminate the southern boundary of the Amurian plate near South Korea. Data for the period from March 2000 to August 2003 are analyzed together with data from IGS and some Chinese GPS stations. Estimated velocities show that South Korea is almost rigid and the southern boundary of the Amurian plate may not cross South Korea. Using the F-ratio statistical test, we determine whether South Korea belongs to the Amurian or South China plates. The test has shown that the Southern Korean Peninsula neither resides on the Amurian plate as hypothesized, nor is part of the South China block.