Correlation of paleoearthquake records at multiple sites along the southern Yangsan Fault, Korea: Insights into rupture scenarios of intraplate strike-slip earthquakes

Type Article
Date 2023-05
Language English
Author(s) Kim Taehyung1, Choi Jin-Hyuck1, Cheon Youngbeom1, Lee Tae-Ho1, Kim Namgwon2, Lee Hoil1, Kim Chang-Min1, Choi Yire1, Bae Hankyung1, 3, Kim Young-Seog4, Ryoo Chung-Ryul1, Klinger Yann5
Affiliation(s) 1 : Active Tectonics Research Center, Korea Institute of Geosciences and Mineral Resources, Daejeon 34132, Republic of Korea
2 : Department of Civil and Environmental Engineering, University of Strathclyde, Galasgow G11XJ, UK
3 : Department of Geology, Kangwon National University, Chuncheon 24341, Republic of Korea
4 : Department of Earth and Environmental Sciences, Pukyong National University, Busan 48513, Republic of Korea
5 : Université de Paris Cité, Institut de physique du globe de Paris, CNRS, Paris, France
Source Tectonophysics (0040-1951) (Elsevier BV), 2023-05 , Vol. 854 , P. 229817 (16p.)
DOI 10.1016/j.tecto.2023.229817
WOS© Times Cited 5
Keyword(s) Intraplate area, Southern Yangsan Fault, Rupture scenario, Partial rupture, Geometric discontinuity
Abstract

he construction of spatiotemporal models of earthquake occurrence for intraplate areas is challenging due to the low deformation rates in these areas. In this study, we conducted paleoseismological investigations along the southern Yangsan Fault (SYF), a typical low-deformation-rate fault, on the Korean Peninsula. The SYF is distinct from the northern Yangsan Fault (NYF), and the boundary between them is located at the junction between the NNE-striking YF and another major structure, the NNW-striking Ulsan Fault (UF), which branches off from the YF. Paleoseismological trenches at four sites along the SYF indicate that this fault section has not ruptured during the Holocene, in contrast to the NYF and UF. In detail, surface ruptures along the studied section of the SYF occurred during three different time periods, as inferred from stratigraphy and radiocarbon dating: 74 to 49 ka at two sites, 39 to 35 ka at another site, and 28,000 cal yr BP (or 30 ka considering the OSL age) to 16 ka at all sites. These results suggest two alternative rupture scenarios for the timing of paleoearthquakes along the studied fault section during the Late Pleistocene: (1) full rupture along the entire studied section during each earthquake event, or (2) multiple partial ruptures along the two structurally distinguishable parts of the studied fault section, that is, the Wolsan–Miho and Inbo north–Inbo sections. We conclude that geometric discontinuities of the long-lived YF system in the Korean Peninsula intraplate region have played an important role in controlling recent spatiotemporal rupture behavior.

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Kim Taehyung, Choi Jin-Hyuck, Cheon Youngbeom, Lee Tae-Ho, Kim Namgwon, Lee Hoil, Kim Chang-Min, Choi Yire, Bae Hankyung, Kim Young-Seog, Ryoo Chung-Ryul, Klinger Yann (2023). Correlation of paleoearthquake records at multiple sites along the southern Yangsan Fault, Korea: Insights into rupture scenarios of intraplate strike-slip earthquakes. Tectonophysics, 854, 229817 (16p.). Publisher's official version : https://doi.org/10.1016/j.tecto.2023.229817 , Open Access version : https://archimer.ifremer.fr/doc/00830/94151/