Tectonic Environment of the 1999 Chi-Chi Earthquake in Central Taiwan and its Aftershock Sequence

Wang, Cheng-sung; Huang, T.; Yen, I-Chin; Wang, Su-Long; Cheng, Win-Bin

doi:10.3319/tao.2000.11.3.661(cce)

Cited by 7 publications

(12 citation statements)

References 10 publications

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“…Interestingly, focal mechanisms for the mainshock and immediate aftershocks of the 1999 earthquake constrain the fault dip between 25Њ and 30Њ east at 5-10 km depth (Fig. 2) (Hung and Suppe, 2000;Kao and Chen, 2000;Wang et al, 2000;Ma et al, 2001;Shin and Teng, 2001;Lee et al, 2002). This indicates there must be a bend in the fault in the northern CDR-7 CDR-10 CDR-4 CDR-1 CDR-11(~50m) CDR-12 (~100m) CDR-5 region.…”

Section: Discussionmentioning

confidence: 96%

“…Outcrops and seismic profiles in the southern region indicate the fault dips 20Њ-35Њ (Chang, 1971;Ho and Chen, 2000;Lee et al, 2001a) east. Focal mechanism solutions from the 1999 earthquake indicate thrust motion that ruptured on a 15Њ-30Њ, eastdipping fault between 5 and 10 km depth (Hung and Suppe, 2000;Kao and Chen, 2000;Wang et al, 2000;Ma et al, 2001). The southern region therefore is a planar fault to depth (Fig.…”

Section: Geologic Settingmentioning

confidence: 95%

“…1, 2a). Thus, the recent earthquake was an out-of-sequence event within the fold-and-thrust belt (Morley, 1988;Kao and Chen, 2000;Wang et al, 2000;Chen et al, 2001b).…”

Section: Geologic Settingmentioning

confidence: 98%

“…Focal mechanism solutions from the 1999 earthquake indicate that the fault ruptured along a 20Њ-30Њ, eastdipping fault between 5 and 10 km depth (Kao and Chen, 2000;Wang et al, 2000;Ma et al, 2001). Therefore, the fault can be considered a planar fault in the southern region but must bend or have a different geometry, at least near the surface, in the northern region.…”

Section: Introductionmentioning

confidence: 97%

“…1). Additionally, core data from two sites (Y. H. Lee, personal comm., 2002;Liao et al, 2002), outcrop analysis (Lin et al, 2001), and seismic reflection profiles (Chang, 1971;Wang et al, 2000) are reviewed to examine the fault structure variations from the north to the south.…”

Section: Introductionmentioning

confidence: 99%

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Fault Structure Control on Fault Slip and Ground Motion during the 1999 Rupture of the Chelungpu Fault, Taiwan

Heermance

Shipton

Evans

2003

Bulletin of the Seismological Society of America

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The Chelungpu fault, Taiwan, ruptured in a M w 7.6 earthquake on 21September 1999, producing a 90-km-long surface rupture. Analysis of core from two holes drilled through the fault zone, combined with geologic mapping and detailed investigation from three outcrops, define the fault geometry and physical properties of the Chelungpu fault in its northern and southern regions. In the northern region the fault dips 45Њ-60Њ east, parallel to bedding in both the hanging wall and footwall, and consists of a narrow (1-20 cm) core of dark gray, sheared clay gouge. The gouge is located at the base of a 30-to 50-m zone of increased fracture density confined asymmetrically to the hanging wall. Microstructural analysis of the fault gouge indicates the presence of extremely narrow clay zones (50-300 lm thick) that are interpreted as the fault rupture surfaces. Few shear indicators are observed outside of the fault gouge, implying that slip was localized within the gouge zone. Slip localization along a bed-parallel surface resulted in a narrow gouge zone that produced less high-frequency ground motion and larger displacements (average 8 m) during the earthquake than in the southern region. Displacement in the southern region averaged only 2 m, but ground shaking consisted of large amounts of highfrequency ground motion. The fault in the southern region dips 20Њ-30Њ at the surface and consists of a wide (20-70 m thick) zone of sheared, foliated shale with numerous gouge zones. These data demonstrate a potential correlation between fault structure (i.e., gouge width, geometry) and earthquake characteristics such as displacement and ground motion (i.e., acceleration).

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Section: Discussionmentioning

confidence: 96%

Section: Geologic Settingmentioning

confidence: 95%

“…1, 2a). Thus, the recent earthquake was an out-of-sequence event within the fold-and-thrust belt (Morley, 1988;Kao and Chen, 2000;Wang et al, 2000;Chen et al, 2001b).…”

Section: Geologic Settingmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

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