Laboratory measurements quantifying elastic properties of accretionary wedge sediments: Implications for slip to the trench during the 2011 Mw 9.0 Tohoku-Oki earthquake

Jeppson, T.; Tobin, H. J.; Hashimoto, Yoshitaka

doi:10.1130/ges01630.1

Cited by 15 publications

(18 citation statements)

References 89 publications

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“…This hinders understanding of the additional role that realistic elastic properties along the fault have on the dynamics of megathrust events, and may lead to dynamic models in which depth‐dependent fault friction is the only ingredient available to explain seismological observations. On the other hand, in some models (e.g., Kozdon & Dunham, 2013; Ma, 2012), the value of rigidity considered in the shallow megathrust is one order of magnitude larger than the value estimated from drilling samples (Jeppson et al., 2018). The overestimation of elastic properties involved in the shallow rupture may lead to underestimation of slip, uplift and tsunami size (e.g., Geist & Bilek, 2001; Satake, 1994), thus underestimating related hazards.…”

Section: Introductionmentioning

confidence: 97%

The Influence of Depth‐Varying Elastic Properties of the Upper Plate on Megathrust Earthquake Rupture Dynamics and Tsunamigenesis

et al. 2021

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Megathrust earthquakes nucleate within the seismogenic zone (Byrne et al., 1988;Hyndman et al., 1997). The updip limit of this region may vary depending on material properties and thermal conditions along the megathrust (Hyndman et al., 1997), but it is commonly defined between 5 and 10 km depth (Scholz, 1998). Yet, megathrust earthquakes may occasionally rupture through the shallow and apparently aseismic region of the fault (<5 km of depth), particularly in areas with sediment-starved trenches and irregular subducting

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Section: Introductionmentioning

confidence: 97%

The Influence of Depth‐Varying Elastic Properties of the Upper Plate on Megathrust Earthquake Rupture Dynamics and Tsunamigenesis

et al. 2021

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“…A pore pressure of 1 MPa was maintained throughout. A detailed description of the method is provided in the supporting information (see also Jeppson & Tobin, 2015; Jeppson et al, 2018).…”

Section: Methodsmentioning

confidence: 99%

Elastic Properties and Seismic Anisotropy Across the Alpine Fault, New Zealand

Jeppson

Tobin

2020

Geochem Geophys Geosyst

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Seismically detected low‐velocity zones are commonly associated with major crustal faults. In order to accurately interpret these low‐velocity zones and understand processes that produce them, direct measurements of seismic wave speed through fault zone rocks are needed. The Alpine Fault dominates the active transpressional plate boundary of the South Island, New Zealand. We examine heterogeneity by determining elastic properties of the Alpine Fault using Deep Fault Drilling Project (DFDP)‐1 drill core and borehole logs, and outcrop samples from central Alpine Fault field localities. We measured P and S wave velocities on saturated rock samples, in three orthogonal directions, over a range of effective pressures. P and S wave velocities in fault rock range from 2.5 to 5.0 km/s and 1.3 to 2.7 km/s, respectively, consistent with the borehole sonic log. These velocities are slower than those in the surrounding host rock corresponding to a 20% to 40% decrease in velocity, caused by mechanical and chemical alteration processes, extending at least 30 m from the principal slip surface. Hanging wall host rocks are strongly anisotropic, while brittle fault rock and footwall host rock are mostly isotropic. Fault zone trapped wave observations are geometrically and quantitatively consistent with field observations and laboratory measurements of the damage zone. Scale independence of the velocity measurement in this zone across core, log, and field scales shows that drill core and outcrop samples are good proxies for in situ rocks, suggesting that the low velocity is due to microscale features, such as microfractures and clay content.

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“…Slip often localizes within velocity-strengthening clays (Saffer & Marone, 2003;Ikari et al, 2009;Faulkner et al, 2011). Elastic moduli and wave speeds are greatly reduced Jeppson et al, 2018), which generally enhances slip and reduces rupture velocity (Ma & Beroza, 2008;Lotto et al, 2017Lotto et al, , 2018. It is also possible that this region experiences inelastic deformation during great earthquakes (Ma, 2012;Ma & Hirakawa, 2013;Ma & Nie, 2019); however, whether that inelastic deformation takes the form of distributed plastic strain or is instead localized as slip on splays and other structures remains unclear.…”

Section: Dynamic Rupture and Tsunamismentioning

confidence: 99%

“…The soft muds of this frontal region are likely to have distinctly different material and seismic properties than the more consolidated rock further downdip (e.g., Saffer & Marone, 2003;Ikari et al, 2009;Faulkner et al, 2011;Jeppson et al, 2018). As yet, we do not fully understand whether earthquakes can initiate, how slip propagates, and how seismic radiation is emitted within this region, and examples of earthquakes where we can sufficiently resolve slip in the updip section of the megathrust (e.g., 2010 Mentawai, Hill et al, 2012) remain rare.…”

Section: Outstanding Science Questionsmentioning

confidence: 99%

Megathrust Modeling Workshop Report

Dunham¹,

Thomas²,

Becker³

et al. 2020

Preprint

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Recommended model development 25 Viscoelastic earthquake sequence model with fluid transport Global, 3-D, thermo-mechanical mantle circulation model with two-phase flow A flexible modeling framework for multi-physics, multi-scale modeling including rupture, earthquake cycle, and tectonic time scales 27 Conclusions References Appendix: Detailed Workshop Information 50 Workshop Participation 50 Workshop Sessions and Presentations 51

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Laboratory measurements quantifying elastic properties of accretionary wedge sediments: Implications for slip to the trench during the 2011 Mw 9.0 Tohoku-Oki earthquake

Cited by 15 publications

References 89 publications

The Influence of Depth‐Varying Elastic Properties of the Upper Plate on Megathrust Earthquake Rupture Dynamics and Tsunamigenesis

The Influence of Depth‐Varying Elastic Properties of the Upper Plate on Megathrust Earthquake Rupture Dynamics and Tsunamigenesis

Elastic Properties and Seismic Anisotropy Across the Alpine Fault, New Zealand

Megathrust Modeling Workshop Report

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