3D geometry of the Chelungpu thrust system in central Taiwan: Its implications for active tectonics

Kenn Ming Yang, Shiuh Tsann Huang, Jong Chang Wu, Hsin Hsiu Ting, Wen Wei Mei, Min Lee, Hsiang Horng Hsu, Chang Jie Lee

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

This study is aimed at constructing a 3D subsurface geometry of the Chelungpu thrust and its associated structures, as well as examining the implications of the studies results for active tectonics in the area. Nine balanced cross-sections were constructed across the foothills belt in the study area to delineate the subsurface geometry of the major thrusts in the foreland of the fold-and-thrust belt. The Chelungpu thrust cuts down to the subsurface invariably along the base of the Chinshui Shale and is merged with the Changhua thrust into a common décollement at a depth of 5 to 7 kilometers below the sea level. There is a pre-existing normal fault underneath the common décollement of the Changhua and Chelungpu thrusts which accommodates the thickened strata in the hanging wall of the Chelungpu thrust. The restored cross-sections indicate that during its propagation toward the foreland the Chelungpu thrust originally was a low-angle thrust before it met a pre-existing high-angle normal fault, which was then reactivated and became the frontal ramp of the thrust. In the latest stage, displacement along the Changhua thrust left the normal fault behind and kept it underneath the common décollement. The subsurface geometry of the Chelungpu thrust is a uniform curved plane striking N-S, with some local wavy features and a ramp striking E-W in the northern part of the thrust. To the north of the ramp, the fault plane transforms into a spoon-shaped geometry. In the southern part of the study area, the southern end of the Chelungpu thrust is cut off, and its displacement is transferred into a splay thrust that strikes NE-SW and connects the Chelungpu and Shuangtung-Hsiaomao thrusts. At the hypocenter of the Chi-Chi earthquake, not only is the dip angle of the décollement of the Chelungpu thrust gentler, but the depth much shallower than that of the mainshock. As the hypocenter of the mainshock is very close to the pre-existing normal fault underneath the décollement, a connection between them is highly implied. We also suggest that the ramp in the northern part of the Chelungpu thrust provides a stronger strain guide during the subsurface rupture propagation thereby creating the bended surface rupture.

Original languageEnglish
Pages (from-to)143-181
Number of pages39
JournalTerrestrial, Atmospheric and Oceanic Sciences
Volume18
Issue number2
DOIs
Publication statusPublished - 2007 Jun 1

Fingerprint

thrust
geometry
tectonics
normal fault
rupture
cross section
fold and thrust belt
hanging wall
fault plane
dip
shale
transform
sea level

All Science Journal Classification (ASJC) codes

  • Oceanography
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)

Cite this

Yang, Kenn Ming ; Huang, Shiuh Tsann ; Wu, Jong Chang ; Ting, Hsin Hsiu ; Mei, Wen Wei ; Lee, Min ; Hsu, Hsiang Horng ; Lee, Chang Jie. / 3D geometry of the Chelungpu thrust system in central Taiwan : Its implications for active tectonics. In: Terrestrial, Atmospheric and Oceanic Sciences. 2007 ; Vol. 18, No. 2. pp. 143-181.
@article{5299ba1652c244ef9ae01eaae6013801,
title = "3D geometry of the Chelungpu thrust system in central Taiwan: Its implications for active tectonics",
abstract = "This study is aimed at constructing a 3D subsurface geometry of the Chelungpu thrust and its associated structures, as well as examining the implications of the studies results for active tectonics in the area. Nine balanced cross-sections were constructed across the foothills belt in the study area to delineate the subsurface geometry of the major thrusts in the foreland of the fold-and-thrust belt. The Chelungpu thrust cuts down to the subsurface invariably along the base of the Chinshui Shale and is merged with the Changhua thrust into a common d{\'e}collement at a depth of 5 to 7 kilometers below the sea level. There is a pre-existing normal fault underneath the common d{\'e}collement of the Changhua and Chelungpu thrusts which accommodates the thickened strata in the hanging wall of the Chelungpu thrust. The restored cross-sections indicate that during its propagation toward the foreland the Chelungpu thrust originally was a low-angle thrust before it met a pre-existing high-angle normal fault, which was then reactivated and became the frontal ramp of the thrust. In the latest stage, displacement along the Changhua thrust left the normal fault behind and kept it underneath the common d{\'e}collement. The subsurface geometry of the Chelungpu thrust is a uniform curved plane striking N-S, with some local wavy features and a ramp striking E-W in the northern part of the thrust. To the north of the ramp, the fault plane transforms into a spoon-shaped geometry. In the southern part of the study area, the southern end of the Chelungpu thrust is cut off, and its displacement is transferred into a splay thrust that strikes NE-SW and connects the Chelungpu and Shuangtung-Hsiaomao thrusts. At the hypocenter of the Chi-Chi earthquake, not only is the dip angle of the d{\'e}collement of the Chelungpu thrust gentler, but the depth much shallower than that of the mainshock. As the hypocenter of the mainshock is very close to the pre-existing normal fault underneath the d{\'e}collement, a connection between them is highly implied. We also suggest that the ramp in the northern part of the Chelungpu thrust provides a stronger strain guide during the subsurface rupture propagation thereby creating the bended surface rupture.",
author = "Yang, {Kenn Ming} and Huang, {Shiuh Tsann} and Wu, {Jong Chang} and Ting, {Hsin Hsiu} and Mei, {Wen Wei} and Min Lee and Hsu, {Hsiang Horng} and Lee, {Chang Jie}",
year = "2007",
month = "6",
day = "1",
doi = "10.3319/TAO.2007.18.2.143(TCDP)",
language = "English",
volume = "18",
pages = "143--181",
journal = "Terrestrial, Atmospheric and Oceanic Sciences",
issn = "1017-0839",
publisher = "Chinese Geoscience Union",
number = "2",

}

3D geometry of the Chelungpu thrust system in central Taiwan : Its implications for active tectonics. / Yang, Kenn Ming; Huang, Shiuh Tsann; Wu, Jong Chang; Ting, Hsin Hsiu; Mei, Wen Wei; Lee, Min; Hsu, Hsiang Horng; Lee, Chang Jie.

In: Terrestrial, Atmospheric and Oceanic Sciences, Vol. 18, No. 2, 01.06.2007, p. 143-181.

Research output: Contribution to journalArticle

TY - JOUR

T1 - 3D geometry of the Chelungpu thrust system in central Taiwan

T2 - Its implications for active tectonics

AU - Yang, Kenn Ming

AU - Huang, Shiuh Tsann

AU - Wu, Jong Chang

AU - Ting, Hsin Hsiu

AU - Mei, Wen Wei

AU - Lee, Min

AU - Hsu, Hsiang Horng

AU - Lee, Chang Jie

PY - 2007/6/1

Y1 - 2007/6/1

N2 - This study is aimed at constructing a 3D subsurface geometry of the Chelungpu thrust and its associated structures, as well as examining the implications of the studies results for active tectonics in the area. Nine balanced cross-sections were constructed across the foothills belt in the study area to delineate the subsurface geometry of the major thrusts in the foreland of the fold-and-thrust belt. The Chelungpu thrust cuts down to the subsurface invariably along the base of the Chinshui Shale and is merged with the Changhua thrust into a common décollement at a depth of 5 to 7 kilometers below the sea level. There is a pre-existing normal fault underneath the common décollement of the Changhua and Chelungpu thrusts which accommodates the thickened strata in the hanging wall of the Chelungpu thrust. The restored cross-sections indicate that during its propagation toward the foreland the Chelungpu thrust originally was a low-angle thrust before it met a pre-existing high-angle normal fault, which was then reactivated and became the frontal ramp of the thrust. In the latest stage, displacement along the Changhua thrust left the normal fault behind and kept it underneath the common décollement. The subsurface geometry of the Chelungpu thrust is a uniform curved plane striking N-S, with some local wavy features and a ramp striking E-W in the northern part of the thrust. To the north of the ramp, the fault plane transforms into a spoon-shaped geometry. In the southern part of the study area, the southern end of the Chelungpu thrust is cut off, and its displacement is transferred into a splay thrust that strikes NE-SW and connects the Chelungpu and Shuangtung-Hsiaomao thrusts. At the hypocenter of the Chi-Chi earthquake, not only is the dip angle of the décollement of the Chelungpu thrust gentler, but the depth much shallower than that of the mainshock. As the hypocenter of the mainshock is very close to the pre-existing normal fault underneath the décollement, a connection between them is highly implied. We also suggest that the ramp in the northern part of the Chelungpu thrust provides a stronger strain guide during the subsurface rupture propagation thereby creating the bended surface rupture.

AB - This study is aimed at constructing a 3D subsurface geometry of the Chelungpu thrust and its associated structures, as well as examining the implications of the studies results for active tectonics in the area. Nine balanced cross-sections were constructed across the foothills belt in the study area to delineate the subsurface geometry of the major thrusts in the foreland of the fold-and-thrust belt. The Chelungpu thrust cuts down to the subsurface invariably along the base of the Chinshui Shale and is merged with the Changhua thrust into a common décollement at a depth of 5 to 7 kilometers below the sea level. There is a pre-existing normal fault underneath the common décollement of the Changhua and Chelungpu thrusts which accommodates the thickened strata in the hanging wall of the Chelungpu thrust. The restored cross-sections indicate that during its propagation toward the foreland the Chelungpu thrust originally was a low-angle thrust before it met a pre-existing high-angle normal fault, which was then reactivated and became the frontal ramp of the thrust. In the latest stage, displacement along the Changhua thrust left the normal fault behind and kept it underneath the common décollement. The subsurface geometry of the Chelungpu thrust is a uniform curved plane striking N-S, with some local wavy features and a ramp striking E-W in the northern part of the thrust. To the north of the ramp, the fault plane transforms into a spoon-shaped geometry. In the southern part of the study area, the southern end of the Chelungpu thrust is cut off, and its displacement is transferred into a splay thrust that strikes NE-SW and connects the Chelungpu and Shuangtung-Hsiaomao thrusts. At the hypocenter of the Chi-Chi earthquake, not only is the dip angle of the décollement of the Chelungpu thrust gentler, but the depth much shallower than that of the mainshock. As the hypocenter of the mainshock is very close to the pre-existing normal fault underneath the décollement, a connection between them is highly implied. We also suggest that the ramp in the northern part of the Chelungpu thrust provides a stronger strain guide during the subsurface rupture propagation thereby creating the bended surface rupture.

UR - http://www.scopus.com/inward/record.url?scp=34547560563&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=34547560563&partnerID=8YFLogxK

U2 - 10.3319/TAO.2007.18.2.143(TCDP)

DO - 10.3319/TAO.2007.18.2.143(TCDP)

M3 - Article

AN - SCOPUS:34547560563

VL - 18

SP - 143

EP - 181

JO - Terrestrial, Atmospheric and Oceanic Sciences

JF - Terrestrial, Atmospheric and Oceanic Sciences

SN - 1017-0839

IS - 2

ER -