How Friction and Pore-Fluid Pressure Conditions Controlled by Fault Mineral Composition Affect Earthquake Rupture Propagation

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How Friction and Pore-Fluid Pressure Conditions Controlled by Fault Mineral Composition Affect Earthquake Rupture Propagation

https://doi.org/10.21203/rs.3.rs-2236971/v1

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Although direct recovery of frictional features of fault rocks through drilling projects and multiple experimental analyses, such as the Japan Trench Fast Drilling Project and the Nankai Trough Seismogenic Zone Experiment have been recently performed, the conditions of rupture propagation to levels of friction and pore-fluid pressure remains uncertain. In order to invest such issues, we performed dynamic rupture simulations based on experimental friction datasets measured in fault rocks on the Nankai Trough that was ruptured during the 1944 M_w8.0 Tonankai earthquake. A steady-state friction triggered large slip (about 30 m) near the trench, whereas a high friction suppressed the rupture. The condition in which the pore-fluid pressure was nearly equal to the lithostatic stress decreased the slip about 25 m in case of low friction. However, in case of high friction with negative stress drop, the slip reached to around 20 m, because the low shear strength did not arrest the inertial motion of rupture propagation. Such differences in fault-rock properties and fluid conditions, controlled by fault mineral composition, may fundamentally influence on the complexity and the variability of rupture propagation.

Frictional Experiment

Dynamic Simulation

Spectral Element Method

Nankai Trough

Slip-Weakening

1944 Tonankai Earthquake

We have incorporated the results from frictional laboratory experiments by using fault materials into setting initial conditions of the simulation for dynamic rupture propagation
Low level of friction on fault in the Nakai Trough enlarges the slip during dynamic rupture propagation, being compatible to the historical earthquakes
The consideration of pore-pressure inclusion into simulation for dynamic rupture propagation leads large slip regardless of high level of friction

As an earthquake begins, a rupture propagates along the fault and continues as long as there is sufficient stored strain energy to create new rupture surfaces (Kanamori and Broadsky, 2004). The required energy to propagate rupture is dependent on the stress drop (initial shear stress – dynamic shear stress) along the fault. The rupture is also enhanced where the shear friction properties of the fault have larger stress drop and smaller strength excess (Das and Aki, 1977). Thus, such shear friction along the fault is the most important parameter for understanding not only its rupture process, but also the seismic radiation, shear heating, and magnitude of an earthquake (e.g., Scholz, 2002). For during the past half-century, the rock friction has been not only widely investigated in laboratory experiments (Dieterich, 1972; Byelee, 1978) but also estimated from temperatures recorded in the materials of fault surfaces (Hirono et al., 2015) to understand the frictional properties of the fault.

In the 2011 Tohoku-Oki earthquake (Mw 9.0), an extremely broad area was ruptured (e.g., Ide et al., 2011; Lay, 2018). Its rupture reached the seafloor at the Japan Trench (Kodaira et al., 2012) and displayed a very large coseismic slip exceeding 50 m on the near-trench area (e.g., Ito et al., 2011; Yue et al., 2011). Such near-trench huge slip is thought to have caused the gigantic tsunami that followed the earthquake. In order to understand the mechanism to generate such huge slip, the Japan Trench Fast Drilling Project was conducted through Integrated Ocean Drilling Program (IODP) Expeditions 343/343T. Highly sheared clayey fault rock, in which smectite was the dominant component, was successfully recovered from the area that underwent huge shallow slip (Chester et al., 2013; Ujiie et al., 2013; Broadsky et al., 2020). Various properties of the fault rock such as the friction coefficient, porosity, permeability, and kinetic parameters of the thermochemical reactions were measured in the laboratory (Hirono et al., 2016). Numerical simulations of fault slip and rupture propagation based on these measured properties and parameters especially focusing on the shallow part of the fault revealed that ultralow friction along the fault, caused by thermal pressurization through which fluid pressure generated by shear-related heating reduces the fault strength during coseismic slip (Andrews ,2002; Rice, 2006) could have triggered the huge slip near the trench during the 2011 earthquake (Hirono et al., 2019).

The Nankai Trough on the southwest Japan, where historical large earthquakes have been repeatedly occurred, conducted another drilling program penetrated the décollement (the shallow portion of the plate-boundary fault) and the megasplay fault that branches up from the plate interface (Kinoshita et al., 2009). The Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE), conducted during IODP Expeditions 314–316, targeted the rupture area of the 1944 Tonankai earthquake (Mw 8.0) (Park et al., 2002, Fig. 1a), and penetrated the megasplay fault at 258–315 m depth below seafloor at Site C0004 (Ichinose et al., 2003; Fig. 1b), which is thought to be the source of the large tsunamis associated with past 1944 Tonankai earthquakes (e.g., Park et al., 2002, Baba et al., 2006, Moore et al., 2007). The fault zone consists of fractured, brecciated, and microbrecciated deposits of hemipelagic mudstone and volcanic ash, and shear-localized dark fault gouge (Fig. 1c). The gouge, observed at 271.30 m depth with a thickness of 10 mm, is accompanied by a thermal anomaly of the vitrinite reflectance that might be produced by a seismic rupture that propagated from the deeper plate interface (Sakaguchi et al., 2011). The friction coefficients of the dark fault gouge and its surrounding fault breccia were experimentally determined to be 0.06 (Ujiie et al., 2010) and 0.21 (Tanikawa et al., 2012), respectively. Numerical simulations of the slip that took into consideration the effect of thermal pressurization showed that the friction coefficient was still lower, ranging from 0.01 to 0.04 (Hirono et al., 2016).

However, most previous studies to investigate the fault behaviour during subduction earthquakes assumed the genetic fictional properties and performed numerical simulation of dynamic rupture propagation (e.g., Noda and Lapusta, 2013, Kozdon and Dunham, 2012). In order to investigate more realistic fault behaviour, the incorporation of frictional properties of fault material derived from fault area, introduced above, into simulation is necessary. Hirono et al. (2016) conducted the dynamic rupture simulation by using only one data of friction coefficients (0.01–0.04). However, it is unrevealed how other dataset of friction coefficients (Ujiie et al., 2010; Tanikawa et al., 2012) control on the rupture propagation. Furthermore, the initial condition of the pore-fluid pressure before an earthquake might affect rupture propagation because its overpressure, when comparable to the lithostatic stress, reduces the shear stress on the fault. In the Nankai Trough, overpressure zones were observed in the shallow portions of the subducting plate boundary (Screaton et al., 2002, Tsuji et al., 2008, Tobin and Saffer, 2009, Saffer and Tobin, 2011). In order to represent the features of such overpressure zones, the normalized pore pressure ratio (= (pore-fluid pressure – hydrostatic pressure) / (confining pressure – hydrostatic pressure)) was introduced and in and around the décollement and megasplay fault in the Tonankai region this ratio has been determined to be over 0.7 by integrating the high-resolution seismic velocity distribution and frequency-domain waveform tomography (Tsuji et al., 2014). However, it is not clear how such overpressure affects the rupture propagation and the slip.

Therefore, in this study, we have tried to investigate how such frictional properties and pore-fluid pressure conditions have an influence on rupture propagation along the megasplay fault based on dynamic simulations. We first describe all quantitative features of the dataset of friction properties of fault rocks recovered from the megasplay fault which is thought to be the source of the historical large tsunamis in the source regions of the 1944 Tonankai earthquake. We then evaluate the potential for slip quantitatively along the fault by conducting dynamic rupture simulations based on the friction data obtained from actual fault rocks.

2.1 Frictional Properties and pore-fluid pressure conditions

We have used three friction datasets for the fault rocks within the megasplay fault based on laboratory experiments and numerical calculations (Hirono et al., 2016; Ujiie et al, 2010; Tanikawa et al., 2012) to investigate the influences of levels of friction and pore-fluid pressure on the rupture propagation. The first dataset (Hirono et al., 2016) was compiled by applying measured data from permeability–effective pressure and porosity–effective pressure equations, the specific heat capacity, dewatering kinetics under high temperature of the dark fault gouge sample, and other realistic parameters to reconstruct the shear stress-versus-slip curve numerically, taking into consideration thermal and thermochemical pressurizations. This shear stress-versus-slip curve can be expressed by the exponential slip-weakening friction law (Ida, 1972): µ = µ_d – (µ_d – µ_s) exp (–D/Dc), where µ is the friction coefficient as a function of slip, µ_d is the dynamic friction coefficient (friction coefficient at steady state after dynamic weakening), µ_s is the static friction coefficient (friction coefficient at the yielding stress), D is the slip, and Dc is the critical slip distance (necessary slip to reach steady-state sliding), respectively (Fig. 2). The resultant values of µ_s and µ_d in the experiment were 0.37 and 0.01–0.04, respectively (Hirono et al., 2016). The mineral composition of the dark gouge was reported in Hirono et al. (2016) to be quartz (24.8 wt.%) and feldspar (23.2 wt.%) with smectite (24.7 wt.%), illite (2.9 wt.%), other clay minerals (18.5 wt.%), and other non-clay minerals (5.9 wt.%).

The second dataset (Ujiie et al., 2010) resulted from a rotary shear friction experiment performed on 0.5 g of water-saturated powder collected from the dark fault gouge at a slip rate of 1.27 m s^–1 under 0.6–2.0 MPa normal stress. The resultant values of µ_s and µ_d in the experiment were 0.27 and 0.06, respectively. Thermal pressurization was considered to occur during their friction experiment (Ujiie et al., 2010). The mineral assemblage was the same to those in Hirono et al. (2016).

The last dataset (Tanikawa et al., 2012) was based on the fault rock sample, which fault breccia is located at 226.26 m depth within the megasplay fault, used for experimental determination of the friction coefficient. A similar rotary-shear experiment was performed on 1 g of water-saturated powder retrieved from the fault breccia at a slip rate of 1.05 m/s under 1.5 MPa normal stress. The resultant µ_s and µ_d were determined to be 0.347 and 0.210, respectively. Thermal pressurization was considered not to occur during their experiment because of relatively high value of µ_d. The mineral assemblage was reported in Tanikawa et al. (2012) to be quartz (17.8 wt.%) and feldspar (19.8 wt.%) with smectite (38.9 wt.%), illite (15.0 wt.%), and calcite (8.5 wt.%).

High pore-fluid pressure in the shallow portions of accretionary prisms, which form from sediments accreted onto the non-subducting tectonic plate at a convergent plate boundary, has been proposed for half a century (Saffer and Tobin, 2011). The mechanical analyses predicted that accretionary prisms and their basal plate-boundary faults (décollements) must be highly over-pressured to explain active slip on shallowly dipping faults and the ubiquitously observed thinly tapered wedge geometry (e.g, Dahlen, 1990). The distribution of highly pressurized zones is typically estimated by using constraints on sediment consolidation behaviour that are obtained from laboratory experiments or borehole data (Screaton et al., 2002; Gamage and Screaton, 2006) and inferred from seismic interval velocities (Tsuji et al., 2008; Tobin and Saffer, 2009). A recent investigation that integrated high-resolution seismic velocity distribution and frequency-domain waveform tomography has revealed that the normalized pore pressure ratio in and around the megasplay fault ranged from 0.7 to 0.95 (e.g., Tsuji et al., 2014).

2.2 Dynamic Earthquake Rupture Modeling

To simplify the fault geometry, the deep portion of the plate-boundary fault and the megasplay fault in the Nankai Trough were assigned dip angles of 8° and 20° in our simulation (Kamei et al., 2012, Fig. 1d). As following Hirono et al. (2016) focusing on the fault behavior on shallow part of the fault (0–10km), we applied fault-weakening properties such as yield shear stress and dynamic frictional stress determined by the three friction datasets of the megasplay fault rocks. We also assumed the normalized pore pressure ratios two different values, 0.8 and 0.9 referring to the previous studies (Tsuji et al., 2014). Because there are currently no relevant data from which to derive absolute values for the initial shear stress on the fault, the initial stress was set from the friction coefficient of 0.154 by assuming the ratio of strength excess and stress drop of 1.4 from the Japan Trench (Hirono et al., 2016). An earthquake nucleation was manually invoked at 11 km depth below the region where we have assumed weakening features to understand fault behaviour, and the direction and speed of rupture propagation and the evolution of slip along the fault were computed. The dynamical model parameters are summarized in Figs. 3 and 4. We have used the spectral element method (SEM2DPACK, Ampuero, 2012) with a grid spacing of 1 km. We assumed a uniform elastic medium with a density of 2850 kg/m³, P-wave velocity of 6.40 km/s, and S-wave velocity of 3.80 km/s, respectively to represent the seismogenic layer of the Nankai Trough (e.g., Koketsu et al., 2012). We also assumed that the rupture is nucleated at 11 km depth close to the depth where the megasplay fault is branched from plate boundary (Fig. 1d). The part of the fault at middle depth (11–20 km) was assumed to have a stress drop of 3 MPa, which is a representative value for inter-plate earthquakes (Kanamori and Anderson, 1973). In the deeper region below 21 km, we assumed a negative stress drop to prevent rupture propagation into the deeper part. This is because our study is focused on the fault behaviour near the trench and we wanted to avoid the complications of the deeper portion of the fault by using the simple assumption that other parameters were constant below 11 km depth. Model parameters for our dynamic rupture simulation are shown for the entire region, including the area of slip strengthening, in Figs. 3 and 4.

We simulated two-dimensional dynamic rupture propagation on the basis of a slip-weakening friction power law (Ida, 1972) to evaluate how the levels of the friction coefficient of fault rock and the pore-fluid pressure within the megasplay fault affect the process of seismic rupture. The rate- and state-dependent friction (RSF) law has been widely adopted to describe the rock friction data obtained by laboratory experiments at relatively low slip rates (Dieterich, 1972; Ruina, 1983), and to simulate rupture nucleation (Lapusta, et al., 2000; Rubin and Ampuero, 2005) and the pattern of cyclical earthquakes (Noda and Lapusta, 2013). However, fault weakening by thermal pressurization can dominate RSF weakening during earthquake nucleation at slip speeds in excess of roughly 10^–4 m/s (e.g., Schmitt et al., 2011). During dynamic rupture, such slip rates are rapidly exceeded soon after the passage of the rupture front, so that RSF weakening is not dominant after nucleation, during the dynamic phase of coseismic slip. Therefore, we applied the exponential slip-weakening friction law (Ida, 1972), which is consistent with the stress-versus-slip curves obtained from the high-rate friction experiment and numerical modelling (Hirono et al., 2016; Ujiie et al., 2010; Tanikawa., 2012).

When the normalized pore pressure ratio was 0.8, simulations for the case of µ_s = 0.37 and µ_d = 0.01–0.04 (named case 1, Hirono et al., 2016) showed large slip near the trench (about 28, 29, and 30 m at 2, 5, and 8 km depth on the fault, respectively) in Figs. 5a and 5d. Simulations for the case of µ_s = 0.27 and µ_d = 0.06 (named case 2, Ujiie et al., 2010) also showed large slip near the trench (about 30, 31, and 32 m at 2, 5, and 8 km depth on the fault, respectively) in Figs. 5b and 5e. However, simulations for the case of µ_s = 0.347 and µ_d = 0.210 (named case 3, Tanikawa et al., 2012) exhibited almost no slip near the trench (about 0.3 m at all 2, 5, and 8 km depths on the fault) in Figs. 5c and 5f. When the normalized pore pressure ratio was 0.9, simulations for case 1 showed large slip distances near the trench (about 22, 22, and 23 m at 2, 5, and 8 km depth on the fault, respectively) in Figs. 6a and 6d. Simulations for case 2 also showed large slip near the trench (about 23, 23, and 24 m at 2, 5, and 8 km depth on the fault, respectively) in Figs. 6b and 6e. Simulation for case 3 exhibited large slip near the trench (about 20, 21, and 22 m at 2, 5, and 8 km depth on the fault, respectively) in Figs. 6c and 6f.

Under the environmental condition that the normalized pore fluid pressure ratio was 0.8, the fault rocks of both cases 1 and 2 showed about 30 m slip near the trench because they had large stress drops at 1–10 km depth with sufficient energy to propagate rupture. Under the condition that the pore fluid pressure ratio was 0.9, case 1 and 2 faults showed somewhat smaller, but still large slip of about 23 m. Such large slips are enough to generate large tsunamis that are consistent with historical records of large tsunamis accompanying past earthquakes (e.g., Ando, 1975; Furumura, et al., 2011). However, in case 3, under the pore fluid pressure ratio of 0.8 the portion of the fault with negative stress drop at 1–10 km depth served as a barrier to propagation whereas under the 0.9 pore fluid pressure ratio, the slip was large even though the stress drop in this region was negative. These results give us two new insights for understanding rupture propagation: 1) the difference in friction of the fault rocks between case 1 (also case 2) and case 3 indicates that the level of µ_d, that is, of stress drop of the fault rock, is crucial in determining whether the fault enhances or impedes the rupture propagation. 2) the level of the in-situ pore-fluid pressure on the fault just before an earthquake also dramatically affects rupture propagation. High pore pressure that is nearly equal to the lithostatic pressure results in a low level of shear stress on the fault. Such high pore pressure has been considered to cause shallow slow earthquakes that occur adjacent to seismogenic zones (Obara et al., 2005; Obara and Kato, 2016), and the occurrence of slow earthquakes has been shown to coincide with areas of elevated pore pressure (Araki et al., 2017). However, at the same time, ultralow shear stress, caused by high pore pressure, is insufficient to arrest the inertial motion of rupture propagation during large earthquakes. A similar phenomenon was confirmed by extremely low friction in smectite and graphite even without thermal pressurization (Hirono et al., 2019). The shear strength of rocks and minerals has long been measured in laboratory deformation experiments. Many common rocks and minerals have been found to have friction coefficients of 0.6–0.85 (e.g., Byerlee, 1978). However, clay minerals have low friction coefficients; for example, smectite has a friction coefficient of < 0.1 (e.g., Logan and Rauenzahn, 1987) and other common clay minerals (illite, chlorite, and kaolinite) also have low friction coefficients ranging between 0.2 and 0.4. Laboratory experiments that used a mixture of quartz and clay minerals demonstrated that a higher amount of clay minerals in synthetic fault rock lowered the friction coefficient (Shimamoto and Logan, 1981; Brown et al., 2003). Thus, to first order, the shear friction of geologic materials is dependent on the mineralogy and lithology. The difference in the friction coefficients of the megasplay fault rocks between the dark fault gouge of case 1 (also case 2) and the fault breccia of case 3 might also be caused by a difference between their mineral assemblages. However, the mineral composition of incoming sediments into the Nankai Trough is highly variable (Ikari et al., 2018); the total clay content generally ranges from 30 to 80 wt.% and the smectite abundance in the bulk sediment ranges from 10–60% (e.g., Brown et al., 2003; Underwood and Pickenring, 1996). Lateral variation along the trench has also been observed; rocks from the fault offshore of Cape Muroto along the Nankai Trough, approximately 200 km west of the drilling site of IODP Expeditions 314–316, have higher clay mineral content (approx. 60 wt.%) (Brown et al., 2003; Ikari et al., 2018). Dynamic fault weakening, such as thermal pressurization, also depends on the mineralogy and lithology because their controlling permeability and porosity strongly influence the level of pressurization of pore fluid (e.g., Hirono et al., 2016). In addition, diagenesis of incoming fault rocks along a subducting plate changes their mineral compositions, physical properties, friction coefficients, and so on (Vrolijk, 1990). For example, after undergoing burial, smectite transforms to illite with a higher friction coefficient (Saffer and Marone, 2003) in a reaction that is most active at temperatures of 60–100°C and approaches completion at 150°C (e.g., Pytte et al., 1989). Therefore, for more comprehensive understanding of rupture propagation over the entire area of the Nankai Trough, the geological and physical properties of a fault zone, and in situ environmental conditions such as the pore-fluid pressure and the magnitude and distribution of stress, should be directly investigated both by drilling into subduction faults at multiple trench-parallel sites and by deeper drilling at multiple trench-perpendicular sites. The amount of slip and how the rupture extends are sensitive to the friction properties of the fault rocks and the environmental condition of the pore-fluid pressure along subduction faults. This sensitivity might be attributed to the diversity and complexity of the style and the amount of fault slip during earthquake rupture. However, we now have a method to reconstruct the rupture propagation along a fault based on a realistic frictional properties of fault rock dataset by incorporating dynamic rupture simulation. Therefore, an integrated program of drilling into subduction faults and fault rock analysis enable a quantitative assessment of tsunamigenic potential and can contribute to a better understanding of megaquake physics.

In this study, we have tried to investigate how such frictional properties and pore-fluid pressure conditions have an influence on rupture propagation along the megasplay fault, which is thought to be the source of the historical large tsunamis in the Tonankai region. Three dataset of friction properties of fault rocks depending on their mineral compositions, recovered from the megasplay fault has been used to represent the stress conditions such region. And then we have quantitatively evaluated the potential for slip along the fault by integrating a dynamic rupture simulation based on the friction data obtained from actual fault rocks focusing on the shallow part of the fault. The sensitivity of the frictional properties might be attributed to the diversity and complexity of the style and the amount of fault slip during an earthquake. In this study, we have reconstructed the rupture propagation along a fault based on a realistic fault rock dataset by incorporating dynamic rupture simulation. Therefore, an integrated program of drilling into subduction faults and fault rock analysis enable a quantitative assessment of tsunamigenic potential and can contribute to a better understanding of megaquake physics.

Availability of data and materials

We did not use any actual data and the numerical code is already gone public.

Acknowledgements

This research was supported by the Japan Society for the Promotion of Science (JSPS) KAKENHI (JP22K03778).

Authors’ contributions

KT and TH designed this study. TH prepared for the fault material and conducted the experiment to estimate the frictional parameters. KT conducted the numerical simulations for dynamic rupture propagation and summarized the results. KT and TH are contributed to the discussion of the obtained results. Both read and approved the final manuscript.

Funding

This study is partially supported by the internal funding of Shimizu Corporation.

Ethics approval and consent to participate

Not applicable.

Consent for publication

Not applicable.

Competing interests

The authors declare that they have no competing interests.

Ampuero, J. P. (2012) SEM2DPCAK Version 2.3.8. http://web.gps.caltech.edu/~ampuero/soft/users_guide_sem2dpack.pdf.
Ando, M. (1975) Source mechanisms and tectonic significance of historical earthquakes along the Nankai trough, Japan. Tectonophysics 27, 119–140.
Andrews, D. J. A fault constitutive relation accounting for thermal pressurization of pore fluid. J. Geophys. Res. 107(B12), 2363 (2002).
Araki, E. et al. Recurring and triggered slow-slip events near the trench at the Nankai Trough subduction megathrust. Science 356, 1157–1160 (2017).
Baba, T., Cummins, P. R., Hori, T. & Kaneda, Y. High precision slip distribution of the 1944 Tonankai earthquake inferred from tsunami waveforms: Possible slip on a splay fault. Tectonophysics 426, 119–134 (2006).
Brodsky, E. E. et al. The state of stress on the fault before, during, and after a major earthquake. Annu. Rev. Earth Planet. Sci. 48, 49–74 (2020).
Brown, K. M., Kopf, A., Underwood, M. B. & Weinberger, J. L. Compositional and fluid pressure controls on the state of stress on the Nankai subduction thrust: A weak plate boundary. Earth Planet. Sci. Lett. 214, 589–603 (2003).
Byerlee, J. Friction of rocks. Pure Appl. Geophys. 116, 615–626 (1978).
Chester, F. M. et al. Structure and composition of the plate-boundary slip zone for the 2011 Tohoku-Oki earthquake. Science 342, 1208–1211 (2013).
Dahlen, F. A. Critical taper model of fold-and-thrust belts and accretionary wedges. Annu. Rev. Earth Planet. Sci. 18, 55–99 (1990).
Das, S. & Aki, K. A numerical study of two-dimensional spontaneous rupture propagation. Geophys. J. R. Astr. SOC. 50, 643–668 (1977).
Dieterich, J. H. Time-dependent friction in rocks. J. Geophys. Res. 77, 3690–3697 (1972).
Furumura, T., Imai, K. & Maeda, T. A revised tsunami source model for the 1707 Hoei earthquake and simulation of tsunami inundation of Ryujin Lake Kyushu Japan. J. Geophys. Res. 116, B02308 (2011).
Gamage, K. & Screaton, E. Characterization of excess pore pressures at the toe of the Nankai accretionary complex Ocean Drilling Program sites 1173, 1174, and 808: Results of one-dimensional modelling. J. Geophys. Res. 111, B04103 (2006).
Hirono, T., Tsuda, K. & Kaneki, S. Role of weak materials in earthquake rupture dynamics. Scientific Reports 9, 6604 (2019).
Hirono T. et al. Near-trench slip potential of megaquakes evaluated from fault properties and conditions. Scientific Reports 6, 28184 (2016).
Hirono, T. et al. Re-evaluation of frictional heat recorded in the dark gouge of the shallow part of a megasplay fault at the Nankai Trough. Tectonophysics 626, 157–169 (2014).
Ichinose, G. A. et al. Rupture process of the 1944 Tonankai earthquake (Ms 8.1) from the inversion of teleseismic and regional seismograms. J. Geophys. Res. 108, 2497 (2003).
Ide, S., Baltay, A. & Beroza, G. C. Shallow dynamic overshoot and energetic deep rupture in the 2011Mw 9.0 Tohoku-Oki earthquake. Science 332, 1426–1429 (2011).
Ida, Y. Cohesive force across the tip of a longitudinal-shear crack and Griffith specific surface energy. J. Geophys. Res. 77, 3796–3805 (1972).
Ikari, M. J., Kopf, A. J., Hüpers, A. & Vogt, C. Lithologic control of frictional strength 342 variations in subduction zone sediment inputs. Geosphere 14, 604–625 (2018).
Ito, Y. et al. Frontal wedge deformation near the source region of the 2011 Tohoku-Oki earthquake. Geophys. Res. Lett. 38, L00G05 (2011).
Kamei, R., Pratt, R. G. & Tsuji, T. Waveform tomography imaging of a megasplay fault system in the seismogenic Nankai subduction zone. Earth Planet. Sci. Lett. 317-318, 343–353 (2012).
Kanamori, H. & Anderson, D. L. Theoretical basis of some empirical relations in seismology. Bull. Seism. Soc. Am. 65, 1073–1095 (1975).
Kanamori, H. & Brodsky, E. E. The physics of earthquakes. Rep. Prog. Phys. 67, 1429–1496 (2004).
Kinoshita M. et al. Proc. IODP Vols 314/315/316 Washington D.C. (Integrated Ocean Drilling Program Management International (2009).
Kodaira, S. et al. Coseismic fault rupture at the trench axis during the 2011 Tohoku-oki earthquake. Nature Geosci. 5, 646–650 (2012).
Koketsu, K., Miyake, H., & Suzuki, H. Japan Integrated Velocity Structure Model Version 1, 338 Proceedings of the 15th World Conference on Earthquake Engineering, Paper No. 1773, 339 (2012).
Kozdon, J. E. & E. M. Dunham. Rupture to the trench: Dynamic rupture simulations of the 11 March 2011 Tohoku earthquake, Bulletin of the Seismological Society of America, 103(2B), 1275-1289, doi:10.1785/0120120136 (2013).
Lapusta, N., Rice, J. R., Ben-Zion, Y. & Zheng, G. Elastodynamic analysis for slow tectonic loading with spontaneous rupture episodes on faults with rate- and state-dependent friction. J. Geophys. Res. 105, 23765–23789 (2000).
Lay, T. A review of the rupture characteristics of the 2011 Tohoku-oki Mw 9.1 earthquake. Tectonophysics 733, 4–36 (2018).
Logan, J. M. & Rauenzahn, K. A. Frictional dependence of gouge mixtures of quartz and montmorillonite on velocity composition and fabric. Tectonophysics 144, 87–108 (1987).
Moore G. F. et al. Three-dimensional splay fault geometry and implications for tsunami generation. Science 318, 1128–1131 (2007).
Noda, H. & Lapusta, N. Stable creeping fault segments can become destructive as a result of dynamic weakening. Nature 493, 518–521 (2013).
Obara, K. & Ito, Y. Very low frequency earthquakes excited by the 2004 off the Kii Peninsula earthquakes: A dynamic deformation process in the large accretionary prism. Earth Planets Space 57, 321–326 (2005).
Obara, K. & Kato, A. Connecting slow earthquakes to huge earthquakes. Science 353, 253–257 (2016).
Pytte, A. M. & Reynolds, R. C. The thermal transition of smectite to illite in Thermal history of sedimentary basins: Methods and case studies (ed. Naeser, N. D. & McCulloch, T. H.) 133–140 (New York Springer, 1989).
Park, J. O. et al. Splay fault branching along the Nankai subduction zone. Science 297, 1157–1160 (2002).
Rice, J. R. Heating and weakening of faults during earthquake slip. J. Geophys. Res. 111, B05311 (2006).
Rubin, A. M. & Ampuero, J. -P. Earthquake nucleation on (aging) rate and state faults. J. Geophys. Res. 110, B11312 (2005).
Ruina, A. Slip instability and state variable friction laws. J. Geophys. Res. 88, 10359–10370 (1983).
Saffer, D. M. & Tobin, H. J. Hydrogeology and mechanics of subduction zone forearcs: Fluid flow and pore pressure. Annu. Rev. Earth Planet. Sci. 39, 157–186 (2011).
Saffer, D. M. & Marone, C. Comparison of smectite- and illite-rich gouge frictional properties: application to the updip limit of the seismogenic zone along subduction megathrusts. Earth Planet. Sci. Lett. 215, 219–235 (2003).
Sakaguchi A. et al. Seismic slip propagation to the updip end of plate boundary subduction interface faults: Vitrinite reflectance geothermometry on Integrated Ocean Drilling Program NanTro SEIZE cores. Geology 39, 395–398 (2011).
Scholz, C. H. The Mechanics of Earthquakes and Faulting (Cambridge Univ. Press, 2002).
Screaton, E. et al. Porosity loss within the underthrust sediments of the Nankai accretionary complex: Implications for overpressures. Geology 30, 19–22 (2002).
Schmitt, S. V., Segall, P. & Matsuzawa, T. Shear heating-induced thermal pressurization during earthquake nucleation. J. Geophys. Res. 116, B06308 (2011).
Shimamoto, T. & Logan, J. M. Effects of simulated clay gouges on the sliding behavior of Tennessee sandstone. Tectonophysics 75, 243–255 (1981).
Tanikawa, W. et al. Velocity dependence of shear-induced permeability associated with frictional behavior in fault zones of the Nankai subduction zone. J. Geophys. Res. 117, B05405 (2012).
Tsuji, T., Kamei, R. & Pratt, R. G. Pore pressure distribution of a mega-splay fault system in the Nankai Trough subduction zone: Insight into up-dip extent of the seismogenic zone. Earth Planet. Sci. Lett. 396, 165–178 (2014).
Tsuji, T., Tokuyama, H., Pisani, P. C. & Moore, G. Effective stress and pore pressure in the Nankai accretionary prism off the Muroto Peninsula southwestern Japan. J. Geophys. Res. 113, B11401 (2008).
Tobin, H. J. & Saffer, D. M. Elevated fluid pressure and extreme mechanical weakness of a plate boundary thrust Nankai Trough subduction zone. Geology 37, 679–682 (2009).
Ujiie, K. et al. Low coseismic shear stress on the Tohoku-Oki megathrust determined from laboratory experiments. Science 342, 1211–1214 (2013).
Ujiie, K. & Tsutsumi, A. High‐velocity frictional properties of clay‐rich fault gouge in a megasplay fault zone Nankai subduction zone. Geophys. Res. Lett. 37, L24310 (2010).
Underwood, M. B. & Pickering, K. T. Clay-mineral provenance, sediment dispersal patterns, and mudrock diagenesis in the Nankai accretionary prism, southwest Japan. Clays Clay Minerals. 44, 339–356 (1996).
Yue, H. & Lay, T. Inversion of high-rate (1 sps) GPS data for rupture process of the 11 March 2011 Tohoku earthquake (Mw 9.1). Geophys. Res. Lett. 38, L00G09 (2011).
Vrolijk, P. On the mechanical role of smectite in subduction zones. Geology 18, 703–707 (1990).

No competing interests reported.

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How Friction and Pore-Fluid Pressure Conditions Controlled by Fault Mineral Composition Affect Earthquake Rupture Propagation

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Abstract

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Key Points

1. Introduction

2. Simulation Methods

2.1 Frictional Properties and pore-fluid pressure conditions

2.2 Dynamic Earthquake Rupture Modeling

3. Numerical Simulation Results

4. Discussion

5. Conclusions

Declarations

References

Additional Declarations

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