Potential of phyllosilicate dehydration and dehydroxylation reactions to trigger earthquakes

Takahashi, Miki; Mizoguchi, Kazuo; Masuda, Koji

doi:10.1029/2008jb005630

Cited by 11 publications

(7 citation statements)

References 29 publications

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“…[40] From the above discussion, embrittlement at the dehydration temperature could not have been caused by increased pore pressure, known as "dehydration embrittlement" [Raleigh and Paterson, 1965]. Water freed by mineral dehydration can be retained temporarily in a low-permeability zone, causing a temporary increase in pore pressure and a reduction in the apparent frictional strength of a fault [Takahashi et al, 2009]. In this study, however, dehydration caused strengthening of the simulated fault (Figure 4).…”

Section: Shear-induced Dehydration Of Antigorite Gougementioning

confidence: 76%

“…The experimental apparatus for this study was a gas‐medium, high‐pressure, high‐temperature triaxial testing machine at the National Institute of Advanced Industrial Science and Technology (AIST), Japan. The details of the set‐up have been described by Masuda et al [2002] and Takahashi et al [2007, 2009]. The machine consisted of a cylindrical pressure vessel, a loading system, a pressure‐generating system for confining pressure, and two servocontrolled pressure intensifiers capable of applying a maximum of 200 MPa for both confining pressure ( P c ) and pore pressure ( P p ).…”

Section: Methodsmentioning

confidence: 99%

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On the transient response of serpentine (antigorite) gouge to stepwise changes in slip velocity under high-temperature conditions

et al. 2011

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[1] Shear-sliding tests were conducted on serpentine (antigorite) gouge to understand the rheology of serpentine-bearing faults. The experiments were carried out using a constant confining pressure (100 MPa), a constant pore water pressure (30 MPa), and a range of temperatures (from room temperature to 600°C). The transient response in frictional behavior following stepwise changes in the slip velocity were documented at each temperature. Slip rates varied between 0.0115 and 11.5 mm/s. Both the general level of frictional strength and the transient responses changed drastically at around 450°C. As the temperature increased from 400°C to 450°C, the strength of antigorite rose sharply. The transient response also indicated a change in the mode of deformation from flow-type behavior at temperatures below 400°C to frictional behavior (stick-slip) at temperatures above 450°C-500°C. Although only a limited volume of serpentine was involved in the dehydration reaction, X-ray diffraction analyses and scanning electron microscopy observations showed that forsterite had nucleated in the experimental products at the higher temperatures that were associated with frictional behavior. Submicron-sized, streaky forsterite masses in shear-localized zones may be evidence of shear-induced dehydration that caused strengthening and embrittlement of the gouge. Although antigorite rheology is complicated, the subsequent change in friction coefficient per order-ofmagnitude change in sliding velocity increased with both increasing temperature and decreasing velocity, implying that a possible flow mechanism of intragranular deformation became activated.

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Section: Shear-induced Dehydration Of Antigorite Gougementioning

confidence: 76%

Section: Methodsmentioning

confidence: 99%

On the transient response of serpentine (antigorite) gouge to stepwise changes in slip velocity under high-temperature conditions

et al. 2011

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“…Recent frictional experiments with hydrous rocks provided observations for weakening of frictional strength associated with dehydration. Takahashi et al [2009] showed that frictional strength weakens due to dehydration in increasing temperature. In high velocity friction experiments, Hirose and Bystricky [2007] observed dynamic weakening of the fault friction as a result of dehydration induced by frictional heating.…”

Section: Discussionmentioning

confidence: 99%

Rupture characteristics of the 2005 Tarapaca, northern Chile, intermediate‐depth earthquake: Evidence for heterogeneous fluid distribution across the subducting oceanic plate?

Kuge¹,

Kase²,

Urata³

et al. 2010

J. Geophys. Res.

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We examined the rupture of the 2005 Tarapaca, northern Chile, earthquake at about 110 km depth with respect to both kinematic and dynamic characteristics by using regional and teleseismic waveforms. The earthquake has a downdip tensional focal mechanism. The subhorizontal rupture is characterized by two patches of large slip and high stress drop which are aligned nearly in the east‐west direction, being perpendicular to the direction of the Chile Trench. Rupture initiated in the eastern patch and then propagated to the western patch. Between the two patches, there exists a region of nonpositive stress drop and high strength excess, which can cause subshear rupture to propagate from the eastern to the western patches but radiates little seismic waves. Seismic radiation energy from this earthquake tends to be low, which is consistent with the nonpositive stress drop and high strength excess between the two patches. While the physical mechanism of intermediate‐depth earthquakes is still controversial, current leading hypotheses are associated with dehydration within subducting plates. The rupture characteristics of the Tarapaca earthquake can be related to heterogeneous fluid distribution due to the dehydration. The spatial separation and dominant stress of the two large‐slip patches agree with the characteristics of the previously reported double seismic zone beneath Chile. The two patches may be the manifestation of the double seismic zone where dehydration reactions can release fluid. Using a numerical simulation of 3‐D dynamic rupture, we have shown that weakening due to fluid can account for the rupture characteristics of the Tarapaca earthquake.

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“…For each experimental run, we calculated friction (i.e., shear stress τ normalized by normal stress σ n ) on the rupture surface according to the geometry of our experimental apparatus as follows [ Takahashi et al , 2009]:

\frac{τ}{σ_{n}} = \frac{σ_{italicdiff} sin (2 θ)}{2 (σ_{diff} {sin}^{2} (θ) + P_{C})},

where σ diff is the differential stress, θ is the angle between the ruptured surface and the loading direction (30° in this study), and Pc is the effective confining pressure. We first calculated the average differential stress and its error by taking the difference between its maximum value and the average value in the flat portion of the stress–strain curve where axial strain was greater than 4.5%.…”

Section: Resultsmentioning

confidence: 99%

Effect of water on weakening preceding rupture of laboratory‐scale faults: Implications for long‐term weakening of crustal faults

Masuda

Arai

Fujimoto

et al. 2012

Geophysical Research Letters

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[1] The strengths of crustal faults inferred from boreholederived heat-flow measurements and maximum stress orientations are lower than those determined from laboratory measurements. Because long-term changes of fault strength cannot be directly monitored using geophysical techniques, the causes of fault weakening are not well understood. We provide laboratory evidence that supports the view that longterm weakening of the frictional strength of faults is caused by microfracturing at asperity contacts, which is a result of crack growth at subcritical stress levels. We conducted triaxial compression tests on mylonite samples at successively higher temperatures from room temperature to 600°C to accelerate reaction processes so that they were observable at laboratory time-scales. Our results suggest that long-term reductions of fault strength are related to chemical reactions that take place in the presence of water. In the presence of water, frictional strength decreased as temperature increased, whereas it changed little in the absence of water. Thus, the presence of fluids has an important influence on changes of fault strength, and it is not only high fluid pressure that is important. Citation: Masuda, K., T. Arai, K. Fujimoto, M. Takahashi, and N. Shigematsu (2012), Effect of water on weakening preceding rupture of laboratory-scale faults: Implications for long-term weakening of crustal faults, Geophys. Res. Lett., 39,

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Potential of phyllosilicate dehydration and dehydroxylation reactions to trigger earthquakes

Cited by 11 publications

References 29 publications

On the transient response of serpentine (antigorite) gouge to stepwise changes in slip velocity under high-temperature conditions

On the transient response of serpentine (antigorite) gouge to stepwise changes in slip velocity under high-temperature conditions

Rupture characteristics of the 2005 Tarapaca, northern Chile, intermediate‐depth earthquake: Evidence for heterogeneous fluid distribution across the subducting oceanic plate?

Effect of water on weakening preceding rupture of laboratory‐scale faults: Implications for long‐term weakening of crustal faults

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