Microscale anatomy of the 1999 Chi‐Chi earthquake fault zone

Boullier, Anne-Marie; Yeh, En Chao; Boutareaud, S.; Song, Sheng-Rong; Tsai, Chin Ho

doi:10.1029/2008gc002252

Cited by 116 publications

(141 citation statements)

References 104 publications

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“…Warr and Cox (2001) identified a CCA fabric in clay-gouge samples of the Alpine fault in New Zealand where quartz clasts are surrounded by a thick "snowballed" rim of smectite. More recently, CCAs have been recognized in the principal slip zones of the Chelungpu fault in Taiwan (Boullier et al, 2009) and the Tre Monti fault in Apennines, Italy . Based on high-velocity shear experiments, Boutareaud et al (2008Boutareaud et al ( , 2010 and Ferri et al (2010Ferri et al ( , 2011 suggest that CCAs could be a new textural indicator of large slip at co-seismic velocity with thermal pressurization.…”

Section: Clay-clasts Aggregates (Ccas)mentioning

confidence: 99%

“…Both boreholes encountered sandstone, siltstone and shale alternations of late MioceneePliocene marine sediments ( Fig. 2b) Boullier et al, 2009). Several fault strands of the Chelungpu-fault system were crossed by TCDP Holes A and B (Fig.…”

Section: The Tcdp Projectmentioning

confidence: 99%

“…Warr and Cox, 2001;Boullier et al, 2009Boullier et al, , 2011Schleicher et al, 2009;Moore and Rymer, 2012). The upper-left corner shows diffuse broad scattering intensity from non-crystalline material in addition to some individual reflections from crystals.…”

Section: Fault Rock Compositionmentioning

confidence: 99%

“…Based on high-velocity shear experiments, Boutareaud et al (2008Boutareaud et al ( , 2010 and Ferri et al (2010Ferri et al ( , 2011 suggest that CCAs could be a new textural indicator of large slip at co-seismic velocity with thermal pressurization. Boullier et al (2009) suppose that the presence of CCAs in TCDP samples indicate that the gouge was fluidized as a result of frictional heating and thermal pressurization. Smith et al (2011) assume a syntectonic origin of the CCAs by localized fluidization at seismic slip velocities within the principal slip zone.…”

Section: Clay-clasts Aggregates (Ccas)mentioning

confidence: 99%

“…Moore and Rymer, 2012;Holdsworth et al, 2011;Bradbury et al, 2011;Mittempergher et al, 2011;TCDP: Ye et al, 2007;Sone et al, 2007;Ishikawa et al, 2008;Boullier et al, 2009). Here we describe selected SAFOD and TCDP samples to illustrate similarities and differences in fault rock composition.…”

Section: Fault Rock Compositionmentioning

confidence: 99%

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Faulting processes in active faults – Evidences from TCDP and SAFOD drill core samples

Janssen

Wirth

Wenk

et al. 2014

Journal of Structural Geology

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a b s t r a c tThe microstructures, mineralogy and chemistry of representative samples collected from the cores of the San Andreas Fault drill hole (SAFOD) and the Taiwan Chelungpu-Fault Drilling project (TCDP) have been studied using optical microscopy, TEM, SEM, XRD and XRF analyses. SAFOD samples provide a transect across undeformed host rock, the fault damage zone and currently active deforming zones of the San Andreas Fault. TCDP samples are retrieved from the principal slip zone (PSZ) and from the surrounding damage zone of the Chelungpu Fault. Substantial differences exist in the clay mineralogy of SAFOD and TCDP fault gouge samples. Amorphous material has been observed in SAFOD as well as TCDP samples. In line with previous publications, we propose that melt, observed in TCDP black gouge samples, was produced by seismic slip (melt origin) whereas amorphous material in SAFOD samples was formed by comminution of grains (crush origin) rather than by melting. Dauphiné twins in quartz grains of SAFOD and TCDP samples may indicate high seismic stress. The differences in the crystallographic preferred orientation of calcite between SAFOD and TCDP samples are significant. Microstructures resulting from dissolutioneprecipitation processes were observed in both faults but are more frequently found in SAFOD samples than in TCDP fault rocks. As already described for many other fault zones clay-gouge fabrics are quite weak in SAFOD and TCDP samples. Clay-clast aggregates (CCAs), proposed to indicate frictional heating and thermal pressurization, occur in material taken from the PSZ of the Chelungpu Fault, as well as within and outside of the SAFOD deforming zones, indicating that these microstructures were formed over a wide range of slip rates.

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Section: Clay-clasts Aggregates (Ccas)mentioning

confidence: 99%

Section: The Tcdp Projectmentioning

confidence: 99%

Section: Fault Rock Compositionmentioning

confidence: 99%

Section: Clay-clasts Aggregates (Ccas)mentioning

confidence: 99%

Section: Fault Rock Compositionmentioning

confidence: 99%

See 3 more Smart Citations

Faulting processes in active faults – Evidences from TCDP and SAFOD drill core samples

Janssen

Wirth

Wenk

et al. 2014

Journal of Structural Geology

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Lateral variations in the long‐term slip rate of the Chelungpu fault, Central Taiwan, from the analysis of deformed fluvial terraces

et al. 2014

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The Chelungpu fault ruptured during the September 1999 M w 7.6 Chi-Chi earthquake, in Central Taiwan. This event was characterized by coseismic displacements increasing along strike and updip, from south to north. Previous studies suggested that such lateral variations also existed in the long-term fault slip rate, but this has not yet been clearly documented. To address this, we investigate deformed fluvial terraces along the Choushui and Tatu-Wu rivers, in the southern and central segments of the thrust fault. Optical ages of~13 ka to~38 ka obtained for these terraces enable estimation of fault slip rates of 5.8 ± 2.0 and 10.3 ± 1.6/À3.0 mm/yr for the southern and central segments, respectively. We combine these findings with the fault slip rate determined by other authors for the northern segment. Statistical analysis of the data suggests lateral variations in the long-term fault slip rate, with values increasing toward the north. This pattern in the slip rate, averaged over approximately tens of thousand years, is similar to that observed for coseismic displacements during the Chi-Chi earthquake. The similarities in the deformation pattern observed for one earthquake or cumulated over several events suggest that the Chi-Chi earthquake could be characteristic of the earthquakes breaking the Chelungpu fault, with respect to slip distribution. Our results also allow for discussing the plausible evolution of major rivers draining the foothills of central Taiwan over the last~40-60 kyr. IntroductionVariable coseismic slip along fault ruptures is a common observation [e.g., Vigny et al., 2011] and seems to follow generic characteristics that could be related to the physical properties of the fault zones [e.g., Manighetti et al., 2005]. For earthquakes along subduction zones, variable coseismic slip is often correlated to lateral variations in the interseismic coupling of the plate interface [e.g., Chlieh et al., 2008;Métois et al., 2012]. Such variability is probably reproduced over several seismic cycles because variable coseismic slip correlates to longer-term features, such as gravity anomalies [Song and Simons, 2003] or topography [Cubas et al., 2011] of the forearc. For continental faults, lateral slip variability has been observed but the consistency of this variability over different timescales has not been clearly and systematically documented on the same faults [e.g., Manighetti et al., 2001Manighetti et al., , 2005. Lateral variations in long-term slip rates [Tapponnier et al., 2001] and/or cumulative slip [Manighetti et al., 2001] have been reported and are usually attributed to the lateral long-term growth of faults. Continental faults in active mountain ranges, such as in the Himalayas [Ader et al., 2012] or in Taiwan [Ching et al., 2011;Hsu et al., 2009], seem to be fully locked during the interseismic period preceding an earthquake, even though laterally variable coseismic slip has been documented [Dominguez et al., 2003;Xu et al., 2009;Yu et al., 2001]. The question of why such variations ...

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Stability and localization of rapid shear in fluid‐saturated fault gouge: 1. Linearized stability analysis

2014

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Field observations of major earthquake fault zones show that shear deformation is often confined to principal slipping zones that may be of order 1–100 μm wide, located within a broader gouge layer of order 10–100 mm wide. This paper examines the possibility that the extreme strain localization observed may be due to the coupling of shear heating, thermal pressurization, and diffusion. In the absence of a stabilizing mechanism shear deformation in a continuum analysis will collapse to an infinitesimally thin zone. Two possible stabilizing mechanisms, studied in this paper, are rate‐strengthening friction and dilatancy. For rate‐strengthening friction alone, a linear stability analysis shows that uniform shear of a gouge layer is unstable for perturbations exceeding a critical wavelength. Using this critical wavelength we predict a width for the localized zone as a function of the gouge properties. Taking representative parameters for fault gouge at typical centroidal depths of crustal seismogenic zones, we predict localized zones of order 5–40 μm wide, roughly consistent with field and experimental observations. For dilatancy alone, linearized strain rate perturbations with a sufficiently large wavelength will undergo transient exponential growth before decaying back to uniform shear. The total perturbation strain accumulated during this transient strain rate localization is shown to be largely controlled by a single dimensionless parameter E, which is a measure of the dilatancy of the gouge material due to an increase in strain rate.

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Microscale anatomy of the 1999 Chi‐Chi earthquake fault zone

Cited by 116 publications

References 104 publications

Faulting processes in active faults – Evidences from TCDP and SAFOD drill core samples

Faulting processes in active faults – Evidences from TCDP and SAFOD drill core samples

Lateral variations in the long‐term slip rate of the Chelungpu fault, Central Taiwan, from the analysis of deformed fluvial terraces

Stability and localization of rapid shear in fluid‐saturated fault gouge: 1. Linearized stability analysis

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