UPLIFT RATE OF THE SOUTHEASTERN COAST OF KOREAN PENINSULA AND ITS IMPLICATION TO ACTIVE TECTONICS

A number of high-tech industrial facilities and nuclear power plants are installed along the coast of the southeastern part of Korean peninsula. Re-evaluation of active tectonic stability for the coast is the hot issue before enlargement construction. To clarify Quaternary faulting along the coast, digital mapping of marine terrace was done for 65km long from the north to the south with the order of Gampo (A), Bonggili (B), Naari (C), Kwansung (D), Jungja (E), Dangsari (F), Jinha (G), Bihag (H) and Gijang (I). Marine terrace is divided into three platforms excluding Holocene. Paleoshoreline angle of each platform was traced from A to I. From A to E, elevation of flights is increasing: (1) 17m-40m-70m in A-B, (2) 20m-50m-80m in C-F and (3) 25m-60m-95m in D-E. In the southern block of the coast, from G through H to I, only two platforms are occurred. The former shoreline angle of G-H changes from 12m-30m in G-H to 10m-20m in H-I. OSL data from 2nd terrace range from 59ka to 71ka. If considering effect of water contents in sediments, 2nd terrace might be correlated to the 5a of last interglacial stage. Uplift rate of the coast shows a range from 0.288m/ka to 0.528m/ka. Rising rate of marine terrace in A-E increases from 0.368m/ka to 0.528m/ka. However, uplift rate in G-I decreases from 0.368m/ka to 0.288m/ka toward the south. It revealed that the southeastern coast of Korean peninsula was rising during the Quaternary period, and that there were several concealed Quaternary faults cutting the 2nd and 3rd marine terraces. The uplift of marine terraces has been given effect by the-top-up-to-the-west reverse Quaternary faulting, newly discovered along the coastal area.