Thirty-Five-Year Creep Rates for the Creeping Segment of the San Andreas Fault and the Effects of the 2004 Parkfield Earthquake: Constraints from Alignment Arrays, Continuous Global Positioning System, and Creepmeters

Titus, Sarah; DeMets, Charles; Tikoff, Basil

doi:10.1785/0120050811

Cited by 134 publications

(147 citation statements)

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“…2, Table 1) was initiated. Two boreholes Hill and Dibblee (1953), Lee et al (2001), Titus et al (2006) and several other authors; compare text. (A and B) were drilled in the northern part of the Chelungpu thrust fault where the Chiechi earthquake (21 September 1999, Mw 7.69) occurred (Yu et al, 2001).…”

Section: The Tcdp Projectmentioning

confidence: 99%

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: The Tcdp Projectmentioning

confidence: 99%

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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“…The borehole is located near the southern terminus of the central creeping section of the SAF [Titus et al, 2006], to the NW of the epicenter of the M w 6.0, 2004 Parkfield earthquake. Drilling penetrated to 3.2 km true vertical depth (TVD) [Zoback et al, 2011], through Salinian granite and arkosic sandstone of the Pacific Plate, across the SAF, and ended in the Great Valley Formation of the North American Plate (Figure 1).…”

Section: Introductionmentioning

confidence: 99%

Frictional properties of the active San Andreas Fault at SAFOD: Implications for fault strength and slip behavior

2015

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We present results from a comprehensive laboratory study of the frictional strength and constitutive properties for all three active strands of the San Andreas Fault penetrated in the San Andreas Observatory at Depth (SAFOD). The SAFOD borehole penetrated the Southwest Deforming Zone (SDZ), the Central Deforming Zone (CDZ), both of which are actively creeping, and the Northeast Boundary Fault (NBF). Our results include measurements of the frictional properties of cuttings and core samples recovered at depths of ~2.7 km. We find that materials from the two actively creeping faults exhibit low frictional strengths (μ = ~0.1), velocity‐strengthening friction behavior, and near‐zero or negative rates of frictional healing. Our experimental data set shows that the center of the CDZ is the weakest section of the San Andreas Fault, with μ = ~0.10. Fault weakness is highly localized and likely caused by abundant magnesium‐rich clays. In contrast, serpentine from within the SDZ, and wall rock of both the SDZ and CDZ, exhibits velocity‐weakening friction behavior and positive healing rates, consistent with nearby repeating microearthquakes. Finally, we document higher friction coefficients (μ > 0.4) and complex rate‐dependent behavior for samples recovered across the NBF. In total, our data provide an integrated view of fault behavior for the three active fault strands encountered at SAFOD and offer a consistent explanation for observations of creep and microearthquakes along weak fault zones within a strong crust.

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“…[4] Creep of faults and rocks produces smooth and continuous deformation when recorded at the system size, at large scales along faults [e.g., Titus et al, 2006] and at small scales during creep laboratory tests [Heap et al, 2009]. However, the presence of microearthquakes and transient deformation in creeping faults [Lengliné and Marsan, 2009] and acoustic emission (AE) in laboratory experiments [Lei et al, 2000;Heap et al, 2009] suggest that the deformation process is more intermittent and distributed over a wide range of velocities.…”

Section: Introductionmentioning

confidence: 99%

Downscaling of fracture energy during brittle creep experiments

Lengliné¹,

Schmittbuhl²,

Elkhoury³

et al. 2011

J. Geophys. Res.

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[1] We present mode 1 brittle creep fracture experiments along fracture surfaces that contain strength heterogeneities. Our observations provide a link between smooth macroscopic time-dependent failure and intermittent microscopic stress-dependent processes. We find the large-scale response of slow-propagating subcritical cracks to be well described by an Arrhenius law that relates the fracture speed to the energy release rate. At the microscopic scale, high-resolution optical imaging of the transparent material used (PMMA) allows detailed description of the fracture front. This reveals a local competition between subcritical and critical propagation (pseudo stick-slip front advances) independently of loading rates. Moreover, we show that the local geometry of the crack front is self-affine and the local crack front velocity is power law distributed. We estimate the local fracture energy distribution by combining high-resolution measurements of the crack front geometry and an elastic line fracture model. We show that the average local fracture energy is significantly larger than the value derived from a macroscopic energy balance. This suggests that homogenization of the fracture energy is not straightforward and should be taken cautiously. Finally, we discuss the implications of our results in the context of fault mechanics.

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Thirty-Five-Year Creep Rates for the Creeping Segment of the San Andreas Fault and the Effects of the 2004 Parkfield Earthquake: Constraints from Alignment Arrays, Continuous Global Positioning System, and Creepmeters

Cited by 134 publications

References 40 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

Frictional properties of the active San Andreas Fault at SAFOD: Implications for fault strength and slip behavior

Downscaling of fracture energy during brittle creep experiments

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