Retrodeformation analysis of the Quaternary fault in the southeastern Korean Peninsula

초록

The Suryum fault (F1) with subsidiary branches (F2,3) varies in strike from N40 degrees E to N14 degrees E and in dip from <68 to 8 degrees SE with respect to the surface. New evidence helps redefine the frequency of faulting events and allows calculation of net slip rates. A retrodeformation analysis based on stratigraphic correlation and optical stimulated luminescence (OSL) dates of colluvial deposits reveals four events including three-time faulting during the latest Pleistocene: reverse -> landslide -> reverse -> normal. Net slips are in the range of 100-130 cm for F1 at a dip angle of 68 degrees-45 degrees and 84 cm for F2 at a dip angle of 45 degrees. Based on OSL ages of 23,000 +/- 1200 yr and 12,000 +/- 2000 yr, we calculate net slip rates for F1 and F2 ranging from 0.03 to 0.08 mm/yr. The reactivation slip rate on F1 is 0.15-0.4 mm/yr over the last 12,000 +/- 2000-2800 +/- 200 yr. The Suryum reverse faulting might be related to Mw similar to 6-7 earthquakes during the late Pleistocene, based on net slip rates comparable to those of other intraplate regime examples. (C) 2009 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.

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