Surface deformation related to kink-folding above an active fault: Evidence from geomorphic features and co-seismic slips

Lai, K. Robert; Chen, Yue‐Gau; Hung, Jung Chou; Suppe, John; Yue, Li-Fan; Chen, Yawen

doi:10.1016/j.quaint.2005.09.005

Cited by 18 publications

(20 citation statements)

References 6 publications

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“…Seven unpaired terrace levels [ Lai et al ., ], labeled from T1 to T7, T1 being the highest and oldest one, were recognized on the southwestern bank of the Tachia River, while only narrow and younger terraces are visible on the northeastern river bank (Figures ). Distinct terrace levels are separated by ~5 m high to a few 10 m high risers that are subparallel to the modern river.…”

Section: Uplifted and Folded Late Pleistocene Terraces In Hsinshementioning

confidence: 99%

“…Where preserved from streams incision, the scarp shows a continuous gentle slope of 10–15° to the east, connecting ~1°NW sloping terrace reaches (Figures and ). Continuous gravel beds were observed across the scarp from T1a to T1c, attesting for tectonic folding [ Tsai and Sung , ; Lai et al ., ], instead of faulting [ Ku , ; Bonilla , ; Shih et al ., ] or river incision [ Hsu , ]. The scarp morphology indeed differs from the one of terrace risers that is characterized by a sharp shoulder at the upper terrace edge, noticeable even on the oldest risers (Figure ).…”

Section: Uplifted and Folded Late Pleistocene Terraces In Hsinshementioning

confidence: 99%

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Deciphering cumulative fault slip vectors from fold scarps: Relationships between long‐term and coseismic deformations in central Western Taiwan

et al. 2014

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We document the 30 ka cumulative slip history and long-term slip vector azimuth on the northern Chelungpu fault based on a series of fault-bend folded alluvial terraces and draw quantitative relationships between geological structure, deformation observed from the geomorphology, and coseismic displacements during the 1999 M w = 7.6 Chi-Chi earthquake. In our study area, three main terrace levels show progressive folding by kink band migration in relation to the underlying fault geometry, forming a main N-S fold scarp up tõ 193 m high and secondary E-W scarps. Detailed analysis using 5 m resolution digital elevation model allows us to characterize the scarp morphology and quantify the deformation parameters, namely, terrace heights, fold scarp relief, and fold limb width and slope angle. The 3-D deformation of the highest terrace, dated by optically stimulated luminescence at 30.2 ± 4.0 ka, enables to simultaneously determine amplitude and azimuth of the long-term slip vector based on scarp relief. The long-term slip vector, oriented N338°± 6°, is found to parallel the Chi-Chi coseismic displacements in this area. Cumulative slip and dating results yield a constant slip rate of 17.7 ± 2.2 mm/a in the direction N338°± 6°. Late Quaternary shortening rates observed at four sites vary along strike in a similar way to Chi-Chi coseismic displacements. Together with the collinearity of long-term and coseismic slip vectors at our study site, this suggests that Chi-Chi earthquake is a characteristic earthquake for the Chelungpu thrust with recurrence interval~470 years. We also discuss implications for the regional and long-term distribution of shortening in the central Western Foothills.

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Section: Uplifted and Folded Late Pleistocene Terraces In Hsinshementioning

confidence: 99%

Section: Uplifted and Folded Late Pleistocene Terraces In Hsinshementioning

confidence: 99%

Deciphering cumulative fault slip vectors from fold scarps: Relationships between long‐term and coseismic deformations in central Western Taiwan

et al. 2014

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“…The fact that the coseismic rupture of the Chi-Chi earthquake was located exactly at the toe of cumulated Pleistocene geomorphic scarps marked a turning point for morpho-tectonic studies in Taiwan Ota et al, 2005). During the decade following the Chi-Chi earthquake, the emergence of applications using digital elevation models (DEMs) with increasing resolution facilitated, and significantly improved, geological and geomorphic mapping of active faults (e.g., Shyu et al, 2005;Lai et al, 2006;Ota et al, 2006). The advent of new techniques, such as the high-resolution airborne Light Detection and Ranging (LiDAR) data, now enables the production of DEMs with a metric resolution, allowing detecting short wave-length topographic features, even in heavily urbanized areas .…”

Section: Geodynamic and Geological Contextsmentioning

confidence: 99%

Pleistocene alluvial deposits dating along frontal thrust of Changhua Fault in western Taiwan: The cosmic ray exposure point of view

Siamé

Chen

Derrieux

et al. 2012

Journal of Asian Earth Sciences

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“…Furthermore the scarp shape is distinctly different from nearby terrace risers because of its relatively gentle slope (18°) with a kink‐shaped profile as expected for a fold scarp as opposed to a degraded terrace riser or fault scarp (Figure 9b). Post‐Chi‐Chi investigations show it to be a fold scarp based on the 1999 coseismic ground displacement mainly measured by GPS and on the structure reconstruction made from field measurements [ Lai et al , 2006] (BB′ in Figure 2). The configuration at Hsinshe resembles the case at Tsaotun.…”

Section: Site 3 Hsinshe: Another Preexisting Fold Scarpmentioning

confidence: 99%

Coseismic fold scarps and their kinematic behavior in the 1999 Chi‐Chi earthquake Taiwan

et al. 2007

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[1] Discrete scarps that are created or reactivated during large earthquakes are a locus of concentrated hazard. A number of the coseismic scarps activated in the 1999 Chi-Chi earthquake are actually fold scarps, which display several types of ground deformation characterized by localized folding and are distinct from classic fault scarps, which form by a fault cutting the surface. This paper documents and analyzes fold scarps that formed or reactivated in the 1999 Chi-Chi Taiwan earthquake. Our results show the Chi-Chi fold scarps can be generally divided into two types: (1) those associated with folding ahead of the tip of a blind thrust fault at shallow depths and (2) those associated with folding by kink band migration above fault bends at substantial depths ranging from $0.8 to 5 km). The previously published trishear model can be applied to model the former type, while a new curved hinge kink band migration model is provided to describe the behavior of the latter type. A key feature of fold scarps of the second type is that hinge zones are typically wide (25-100 m) relative to the displacement in a single earthquake (1-10 m), which exerts a significant control on fold scarp morphology and evolution. Because the coseismic strains of both types of fold scarps display relatively wide deformation zones (10-100 m) relative to fault scarps, wider set-back zones might be appropriate from a public policy point of view to alleviate the risk to structural damage and collapse resulting from permanent ground deformation.

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Surface deformation related to kink-folding above an active fault: Evidence from geomorphic features and co-seismic slips

Cited by 18 publications

References 6 publications

Deciphering cumulative fault slip vectors from fold scarps: Relationships between long‐term and coseismic deformations in central Western Taiwan

Deciphering cumulative fault slip vectors from fold scarps: Relationships between long‐term and coseismic deformations in central Western Taiwan

Pleistocene alluvial deposits dating along frontal thrust of Changhua Fault in western Taiwan: The cosmic ray exposure point of view

Coseismic fold scarps and their kinematic behavior in the 1999 Chi‐Chi earthquake Taiwan

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