Asthenospheric buoyancy and the origin of high-relief topography along the Cascadia forearc

Bodmer, Miles; Toomey, D. R.; Roering, Joshua J.; Karlstrom, L.

doi:10.1016/j.epsl.2019.115965

Cited by 21 publications

(23 citation statements)

References 65 publications

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“…1). The latter is recently proposed to be related to lower sub-slab buoyancy, which may also be responsible for the forearc topography variation along the margin [16]. The downdip end of the geodetically inferred locking zone is roughly consistent with the depth of ∼ 350 transition temperature from Cascadia geothermal models [8].…”

Section: Introductionsupporting

confidence: 62%

“…The coastal observed uplift rates require nonzero shear stress loading at the base of the locked zone [10]. More recently, Bodmer et al [16] related the geodetic locking variation in the three Cascadia terranes to the asthenospheric buoyancy of subducting plate, which influences the overlying plate topographic development and along-strike variation of strain accumulation in earthquake cycles.…”

Section: Discussionmentioning

confidence: 99%

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Cascadia megathrust earthquake rupture model constrained by geodetic fault locking

Li¹,

Liu²

2022

Preprint

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Paleo-earthquakes along the Cascadia subduction zone inferred from offshore sediments and Japan coastal tsunami deposits approximated to M9+ and ruptured the entire margin. However, due to the lack of modern megathrust earthquake records and generally quiescence of subduction fault seismicity, the potential megathrust rupture scenario and influence of downdip limit of the seismogenic zone are still obscure. In this study we present a numerical simulation of Cascadia subduction zone earthquake sequences in the laboratory-derived rate-and-state friction framework to investigate the potential influence of the geodetic fault locking on the megathrust sequences. We consider the rate-state friction stability parameter is constrained by geodetic fault locking models derived from decadal GPS records, tidal gauge, and leveling-derived uplift rate data along the Cascadia margin. We incorporate historical coseismic subsidence inferred from coastal marine sediments to validate our coseismic rupture scenarios. Earthquake rupture pattern is strongly controlled by the downdip width of the seismogenic, velocity-weakening zone, and by the earthquake nucleation zone size. In our model, along-strike heterogeneous characteristic slip distance is required to generate margin-wide ruptures that result in reasonable agreement between the synthetic and observed coastal subsidence for the A.D. 1700 Cascadia Mw∼9.0 megathrust rupture. Our results suggest geodetically inferred fault locking model can provide a useful constraint on earthquake rupture scenarios in subduction zones.

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Section: Introductionsupporting

confidence: 62%

Section: Discussionmentioning

confidence: 99%

Cascadia megathrust earthquake rupture model constrained by geodetic fault locking

Li¹,

Liu²

2022

Preprint

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“…It is unclear what role the oceanic asthenosphere plays in decoupling the plates from the mantle, in magma generation, and as source material for nearby volcanic systems, and in transporting anomalous material, such as from nearby hotspots. Moreover, there is still debate concerning the nature of seismic anomalies observed in the subslab asthenosphere and what impact they have on subduction dynamics (Bodmer et al, 2018(Bodmer et al, , 2020Hawley et al, 2016;Portner et al, 2017).…”

Section: Improved Resolution Beneath the Forearc And Identification Omentioning

confidence: 99%

“…Though the margin is relatively short (∼1,200 km), along‐strike variations exist in megathrust behavior (Brudzinski & Allen, 2007; McCrory et al., 2012; Schmalzle et al., 2014; Wells et al., 2017), forearc kinematics and structure (Bodmer et al., 2020; Burgette et al., 2009; Kelsey et al., 1994; Leonard et al., 2010; Schmalzle et al., 2014), and mantle structure (Bodmer et al., 2018; Chen et al., 2015). However, the underlying mechanisms giving rise to these variations and how they may be interrelated is still debated.…”

Section: Tectonic Settingmentioning

confidence: 99%

“…(2018) image localized low‐velocities beneath the slab in the north and south using a priori three‐dimensional (3D) starting models that include elevation to account for near‐surface structure. Understanding how these methodological choices influence the tomographic results is important because there is pronounced variability in along strike subduction behavior (e.g., plate locking, tremor density, long‐term uplift rates, and seismicity; Bodmer et al., 2020; Brudzinski & Allen, 2007; McCrory et al., 2012; Schmalzle et al., 2014), and it is still unknown to what extent the dynamics of the oceanic asthenosphere influence these processes.…”

Section: Introductionmentioning

confidence: 99%

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Body Wave Tomography of the Cascadia Subduction Zone and Juan de Fuca Plate System: Identifying Challenges and Solutions for Shore‐Crossing Data

Bodmer

Toomey

VanderBeek

et al. 2020

Geochem Geophys Geosyst

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Subduction zones are regions where oceanic lithosphere is recycled into the mantle, the largest earthquakes and tsunamis are generated, continental crust is built through accretion and arc magmatism, and volatiles are circulated, key to the petrogenesis, transport, storage, and eruption of magmas (Stern, 2002). Fundamentally, subduction processes are dependent upon properties of both the incoming oceanic lithosphere, the overriding plate, and the surrounding convecting mantle. Worldwide, subduction systems have been studied extensively with seismic methods, producing images of the convergent margin structure, characterizing and cataloging regional seismicity, and developing hazard assessments. Most seismic datasets are inherently limited, however, comprised of only land-based observations and lacking comparable data from the offshore oceanic plate. Those studies capable of obtaining coincident, shore-crossing data are often limited in their spatial scope (e.g., Parsons et al., 2005; Trehu et al., 1994). Only recently, through experiments such as the community-driven Cascadia Initiative (CI), are we able to collect dense, amphibious seismic data spanning large portions of a subduction margin (Toomey et al., 2014). A key takeaway from the CI is that characterizing the structure of oceanic asthenosphere is critical to understanding subduction dynamics, yet, relatively few studies have investigated joint onshore-offshore structure (

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Tectonic Geomorphology Above Mediterranean Subduction Zones

Wegmann¹,

Gallen²

2022

Treatise on Geomorphology

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Asthenospheric buoyancy and the origin of high-relief topography along the Cascadia forearc

Cited by 21 publications

References 65 publications

Cascadia megathrust earthquake rupture model constrained by geodetic fault locking

Cascadia megathrust earthquake rupture model constrained by geodetic fault locking

Body Wave Tomography of the Cascadia Subduction Zone and Juan de Fuca Plate System: Identifying Challenges and Solutions for Shore‐Crossing Data

Tectonic Geomorphology Above Mediterranean Subduction Zones

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