Strong velocity weakening and powder lubrication of simulated carbonate faults at seismic slip rates

Han, Raehee; Hirose, Takehiro; Shimamoto, Toshihiko

doi:10.1029/2008jb006136

Cited by 186 publications

(176 citation statements)

References 62 publications

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“…It is worth a note here that the previously reported increases in stress drop (e.g., Mayeda et al, 2007) have been used to argue for a fundamental change in the earthquake physics above some threshold magnitude. For instance, formation of melt associated with large slip confined to a narrow rupture zone (e.g., Di Toro and Pennacchioni, 2005), thermal pressurization (e.g., Sibson, 1973;Lachenbruch, 1980), elastohydrodynamic lubrication (Brodsky and Kanamori, 2001), or chemical decomposition (Han et al 2010;De Paola et al, 2011) might be expected to reduce the resistance to slip and therefore increase the stress drop. It is conceivable that these types of weakening processes alter the scaling model proposed in our study when a critical event size is reached.…”

Section: Evolution Of Stress Drop With Magnitudementioning

confidence: 99%

Stress Drop during Earthquakes: Effect of Fault Roughness Scaling

Candela

Renard

Bouchon

et al. 2011

Bulletin of the Seismological Society of America

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We propose that a controlling parameter of static stress drop during an earthquake is related to the scaling properties of the fault-surface topography. Using high resolution laser distance meters, we have accurately measured the roughness scaling properties of two fault surfaces in different geological settings (the French Alps and Nevada). The data show that fault-surface topography is scale dependent and may be accurately described by a self-affine geometry with a slight anisotropy characterized by two extreme roughness exponents (H R ), H jj 0:6 in the direction of slip and H ⊥ 0:8 perpendicular to slip.Disregarding plastic processes like rock fragmentation and focusing on elastic deformation of the topography, which is the dominant mode at large scales, the stress drop is proportional to the deformation, which is a spatial derivative of the slip. The evolution of stress-drop fluctuations on the fault plane can be derived directly from the self-affine property of the fault surface, with the length scale (λ) as std Δσ λ ∝ λ H R 1 . Assuming no characteristic length scale in fault roughness and a rupture cascade model, we show that as the rupture grows, the average stress drop, and its variability should decrease with increasing source dimension. That is for the average stress drop Δσr ∝ r H R 1 , where r is the radius of a circular rupture. This result is a direct consequence of the elastic squeeze of fault asperities that induces the largest spatial fluctuations of the shear strength before and after the earthquake at local (small) scales with peculiar spatial correlations.

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Section: Evolution Of Stress Drop With Magnitudementioning

confidence: 99%

Stress Drop during Earthquakes: Effect of Fault Roughness Scaling

Candela

Renard

Bouchon

et al. 2011

Bulletin of the Seismological Society of America

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“…This experimental work resulted in the identification of several potential dynamic weakening mechanisms, such as melt lubrication (Hirose and Shimamoto 2005;Spray 2005;Di Toro et al 2006), thermal decomposition (Han et al 2007;Brantut et al 2008), nanoparticle lubrication (Han et al 2010), and silica gel lubrication (Goldsby and Tullis 2002;). However, our understanding of these dynamic weakening processes, and their dependence on normal stress (note that experiments were performed at\1 MPa in the case of gouges and \20 MPa in the case of cohesive rocks) and slip rate (\2 m s -1 and at constant slip rate conditions with the exception of Sone and Shimamoto 2009), is so limited that they have not yet been explicitly introduced into any earthquake rupture model.…”

Section: Friction Experiments and Earthquake Mechanicsmentioning

confidence: 99%

From field geology to earthquake simulation: a new state-of-the-art tool to investigate rock friction during the seismic cycle (SHIVA)

Toro

Niemeijer

Tripoli³

et al. 2010

Rend. Fis. Acc. Lincei

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Despite considerable effort over the past several decades, the mechanics of earthquake rupture remains largely unknown. Moderate-to large-magnitude earthquakes nucleate at 7-15 km depth and most information is retrieved from seismology, but information related to the physico-chemical processes active during rupture propagation is below the resolution of this method. An alternative approach includes the investigation of exhumed faults, such as those described here from the Adamello Massif (Italian Alps), and the use of rock deformation apparatus capable of reproducing earthquake deformation conditions in the laboratory. The analysis of field and microstructural/mineralogical/geochemical data retrieved from the large glacier-polished exposures of the Adamello (Gole Larghe Fault) provides information on earthquake source parameters, including the coseismic slip, the rupture directivity and velocity, the dynamic friction and earthquake energy budgets. Some of this information (e.g., the evolution of the friction coefficient with slip) can be tested in the laboratory with the recently installed Slow to HIgh Velocity Apparatus (SHIVA). SHIVA uses two brushless engines (max power 280 kW) and an air actuator in a rotary shear configuration (nominally infinite displacement) to slide solid or hollow rock cylinders (40/50 mm int/ext diameter) at: (1) slip rates ranging from 10 lm s -1 up to 9 m s -1; (2) accelerations up to 80 m s -2 ; and (3) normal stresses up to

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“…After flash weakening, progressive seismic slip triggered decarbonation reactions, CO 2 emission and, possibly, the activation of grain size dependent and crystal plastic processes [18,[21][22][23][24]. In the case of quartz-rich rocks, especially under wet conditions and low normal stresses (<5 MPa), weakening at the seismic slip was associated with the production of lubricating silica gels [25,26].…”

Section: Introductionmentioning

confidence: 99%

Dislocation Motion and the Microphysics of Flash Heating and Weakening of Faults during Earthquakes

et al. 2016

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Abstract:Earthquakes are the result of slip along faults and are due to the decrease of rock frictional strength (dynamic weakening) with increasing slip and slip rate. Friction experiments simulating the abrupt accelerations (>>10 m/s 2 ), slip rates (~1 m/s), and normal stresses (>>10 MPa) expected at the passage of the earthquake rupture along the front of fault patches, measured large fault dynamic weakening for slip rates larger than a critical velocity of 0.01-0.1 m/s. The dynamic weakening corresponds to a decrease of the friction coefficient (defined as the ratio of shear stress vs. normal stress) up to 40%-50% after few millimetres of slip (flash weakening), almost independently of rock type. The microstructural evolution of the sliding interfaces with slip may yield hints on the microphysical processes responsible for flash weakening. At the microscopic scale, the frictional strength results from the interaction of micro-to nano-scale surface irregularities (asperities) which deform during fault sliding. During flash weakening, the visco-plastic and brittle work on the asperities results in abrupt frictional heating (flash heating) and grain size reduction associated with mechano-chemical reactions (e.g., decarbonation in CO 2 -bearing minerals such as calcite and dolomite; dehydration in water-bearing minerals such as clays, serpentine, etc.) and phase transitions (e.g., flash melting in silicate-bearing rocks). However, flash weakening is also associated with grain size reduction down to the nanoscale. Using focused ion beam scanning and transmission electron microscopy, we studied the micro-physical mechanisms associated with flash heating and nanograin formation in carbonate-bearing fault rocks. Experiments were conducted on pre-cut Carrara marble (99.9% calcite) cylinders using a rotary shear apparatus at conditions relevant to seismic rupture propagation. Flash heating and weakening in calcite-bearing rocks is associated with a shock-like stress release due to the migration of fast-moving dislocations and the conversion of their kinetic energy into heat. From a review of the current natural and experimental observations we speculate that this mechanism tested for calcite-bearing rocks, is a general mechanism operating during flash weakening (e.g., also precursory to flash melting in the case of silicate-bearing rocks) for all fault rock types undergoing fast slip acceleration due to the passage of the seismic rupture front.

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Strong velocity weakening and powder lubrication of simulated carbonate faults at seismic slip rates

Cited by 186 publications

References 62 publications

Stress Drop during Earthquakes: Effect of Fault Roughness Scaling

Stress Drop during Earthquakes: Effect of Fault Roughness Scaling

From field geology to earthquake simulation: a new state-of-the-art tool to investigate rock friction during the seismic cycle (SHIVA)

Dislocation Motion and the Microphysics of Flash Heating and Weakening of Faults during Earthquakes

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