Quaternary fault analysis through a trench investigation on the northern extension of the Yangsan fault at Dangu-ri, Gyungju-si, Gyeongsangbuk-do

Lee, Jinhyun; Rezaei, Sowreh; Hong, Yea-Ji; Choi, Jin‐Hyuck; Choi, Jungsoon; 최원학,; Woo, Rhee Kun; Kim, Young‐Seog

doi:10.14770/jgsk.2015.51.5.471

Cited by 36 publications

(11 citation statements)

References 7 publications

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“…On the basis of these paleoseismic records, the section has been regarded as one of the most active parts of the >200 km-long Yangsan Fault. After initial observations of a fault outcrop by Ryoo et al (1999), paleoseismic studies through trench surveys were conducted by Lee et al (2015) and Song et al (2020). Song et al (2020) discovered that (a) at least three ruptures occurred during the Quaternary, and the most recent movement was after 3.2 ka, based on the OSL ages of transected strata; (b) the paleoseismic fault shows a steeply east-dipping geometry and splits into seven splays toward the surface, with the dip angles of the splays tending to decrease toward the surface, giving an arc-like geometry; (c) the kinematics of the ruptures are dextral slip with a minor reverse component; and (d) the surface ruptures resulted from propagation between the western margin of the main mature fault core and the A-type alkali feldspar granite (Figure 3a).…”

Section: Byeokgye Section Of the Yangsan Faultmentioning

confidence: 99%

Long‐Term Weakening Processes and Short‐Term Seismic Slip Behavior of an Intraplate Mature Fault Zone: A Case Study of the Yangsan Fault, SE Korea

et al. 2022

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An intraplate tectonic fault evolves with repeated seismic cycles that may exhibit multi‐mode slip behaviors (continuous aseismic sliding, slow slip with silent earthquakes, and earthquakes resulting from stick‐slip frictional instability). Here, we show long‐term (geological time scale) fault zone weakening processes and short‐term (seismic cycle scale) fault behavior of the Yangsan Fault, SE Korea, based on structural and mineralogical observations of an across‐strike fault zone sequence retrieved by inclined borehole drilling. Since the Late Cretaceous, physical and chemical weakening processes have formed a wide and complex fault zone characterized by interconnected clay‐rich fault core strands and fractured lenses. The deformation is more concentrated in the eastern block (Cretaceous sedimentary rock with felsic dikes) of the fault zone than in the western block (Paleogene granite) of the fault zone. The asymmetrical deformation pattern is controlled by the distinct properties of the different host rocks and differential fluid‐assisted reaction softening involving hydrothermal processes. Of the five main strands and numerous subsidiary strands in the wide fault zone, strand S1 between the sedimentary rock and granite has accommodated the largest displacements. In particular, the smectite‐rich, <2‐cm‐wide principal slip zone within S1 has acted as the major pathway for past seismic slip. Our findings consider that slow deformation in the sedimentary rocks formed the asymmetrical wide fault zone over long geological time, whereas that the preferential propagation of repeated seismic slip events propagated preferentially along the narrow principal slip zone of S1.

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Section: Byeokgye Section Of the Yangsan Faultmentioning

confidence: 99%

Long‐Term Weakening Processes and Short‐Term Seismic Slip Behavior of an Intraplate Mature Fault Zone: A Case Study of the Yangsan Fault, SE Korea

et al. 2022

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“…1990년대 중반 양산-울산 단층계 (Yangsan-Ulsan fault system)에서 제4기 단층이 처 음 보고된 이래 (Okada et al, 1994), 이들 단층계를 따라 약 30개 이상의 소규모 제4기 단층지점들이 보 고되어 왔다( Fig. 1; Okada et al, 1999;Lee and Schwarcz, 2001;Choi, 2003;Kim et al, 2004;Kyung and Lee, 2006;Kee et al, 2007;Choi et al, 2014;Choi et al, 2015;Lee et al, 2015). 근래에는 제4기 단층들이 한반도 남동부 지역뿐만 아니라 전역에서 보고되고 있으며 (Choi et al, 2012), 한반도 내에서 중·소규모의 계기 지진이 종종 관측되고 있다 (Jeon and Jun, 2010;Hong et al, 2015).…”

Section: 서 론unclassified

“…Distribution of surface ruptures and deformations identified during the emergency survey after the earthquake. The base map is from the Active Fault Map in Urban Area (Ikeda et al, 2001) by the Geospatial Information Authority of Japan (modified from GSJ, 2016 (Kim et al, 2000;Choi et al, 2007;Choi et al, 2002;Park, 2004;Han et al, 2009;Choi et al, 2012;Lee et al, 2015)을 구마모토 지진의 전파 사례와 비교·분석하였다.…”

Section: 서 론mentioning

confidence: 99%

“…셋 째, 양산-울산단층으로 구획되는 지역이 시계방향으로 회전되고 경동되어 있다 (Choi et al, 2001. (Choi, 2003;Lee and Yang, 2003;Kim et al, 2011;Lee et al, 2015). 지금까 지 발견된 제4기 단층 중에서는 유계단층과 단구단층 이 가장 젊은 단층으로 보고되었다.…”

Section: 구마모토 지진과 후타가와-히나구 단층계unclassified

“…3, 2016 부터 저각까지 다양하다. 또한 같은 단층을 연구한 논문과 보고서에서도 주향 경사가 상이한 경우도 있 다 (Kyung and Chang, 2001;Kim and Jin, 2006;Kee et al, 2007;Kee et al, 2009;Kim et al, 2011;Choi et al, 2012) Okada et al, 1998;Kyung and Chang, 2001;Choi, 2003;Choi et al, 2012;Lee et al, 2015;GSJ, 2016 …”

Section: 구마모토 지진과 후타가와-히나구 단층계unclassified

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Research on Earthquake Occurrence Characteristics Through the Comparison of the Yangsan-ulsan Fault System and the Futagawa-Hinagu Fault System

이진현¹,

권세현²,

김영석³

2016

The Journal of the Petrological Society of Korea

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The understanding of geometric complexity of strike-slip Fault system can be an important factor to control fault reactivation and surface rupture propagation under the regional stress regime. The Kumamoto earthquake was caused by dextral reactivation of the Futagawa-Hinagu Fault system under the E-W maximum horizontal principal stress. The earthquakes are a set of earthquakes, including a foreshock earthquake with a magnitude 6.2 at the northern tip of the Hinagu Fault on April 14, 2016 and a magnitude 7.0 mainshock which generated at the intersection of the two faults on April 16, 2016. The hypocenters of the main shock and aftershocks have moved toward NE direction along the Futagawa Fault and terminated at Mt. Aso area. The intersection of the two faults has a similar configuration of λ-fault. The geometries and kinematics, of these faults were comparable to the Yansan-Ulsan Fault system in SE Korea. But slip rate is little different. The results of age dating show that the Quaternary faults distributed along the northern segment of the Yangsan Fault and the Ulsan Fault are younger than those along the *Corresponding author

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A multidisciplinary approach to characterization of the mature northern Yangsan fault in Korea and its active faulting

Choi

Lee

et al. 2022

Mar Geophys Res

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Quaternary fault analysis through a trench investigation on the northern extension of the Yangsan fault at Dangu-ri, Gyungju-si, Gyeongsangbuk-do

Cited by 36 publications

References 7 publications

Long‐Term Weakening Processes and Short‐Term Seismic Slip Behavior of an Intraplate Mature Fault Zone: A Case Study of the Yangsan Fault, SE Korea

Long‐Term Weakening Processes and Short‐Term Seismic Slip Behavior of an Intraplate Mature Fault Zone: A Case Study of the Yangsan Fault, SE Korea

Research on Earthquake Occurrence Characteristics Through the Comparison of the Yangsan-ulsan Fault System and the Futagawa-Hinagu Fault System

A multidisciplinary approach to characterization of the mature northern Yangsan fault in Korea and its active faulting

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