Relationship between slab dip and topography segmentation in an oblique subduction zone: Insights from numerical modeling

Cerpa, Nestor G.; Araya, Rodolfo; Gerbault, Muriel; Hassani, Riad

doi:10.1002/2015gl064047

Cited by 25 publications

(24 citation statements)

References 44 publications

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“…An approximate solution to the continuous problem (equation (S1-1)) is computed using the finite element code Adeli (Hassani et al, 1997). Adeli has been used to simulate a variety of geodynamical contexts, including subduction zones (Cerpa et al, 2015;Hassani et al, 1997) and the seismic cycle (Contreras et al, 2016;He & Chery, 2008). This code uses the dynamic relaxation method (Cundall, 1989;Cundall & Board, 1988) to solve the set of non linear equations obtained after a finite element discretization of the quasi-static equilibrium equation.…”

Section: Methodsmentioning

confidence: 99%

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Three‐Dimensional Failure Patterns Around an Inflating Magmatic Chamber

Gerbault

Hassani

Lizama

et al. 2018

Geochem Geophys Geosyst

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Bedrock failure around an inflating magma chamber is an important factor that controls the occurrence of volcanic eruptions. Here, we employ 3‐D numerical models of elasto‐plastic shear failure around an inflating crustal reservoir, to study how the induced failure patterns depend on the geometry of the chamber, on the host rock strength and on the gravitational field. Our simulations show that either localized or diffuse plastic failure domains develop in 3 stages. Failure initiates (stage 1) after a critical overpressure is reached, the value of which depends on effective host rock strength. Next, and with increasing applied overpressure, either distributed (for zero friction angle) or localized plastic failure zones (for 30 ° friction angle) form (stage 2), until they finally connect to the surface (stage 3). Cylindrical chambers develop prismatic shear zones that merge from the surface and chamber walls. For spherical and prolate chambers, diffuse conical zones of failure develop from the chamber's crest, whereas for oblate symmetrical chambers, shear bands initiate at the horizontal tips but bend back above the center of the chamber to reach the surface. In contrast for asymmetrical oblate chambers, shear bands initiate in their cylindrical section and vanish along the elongated direction. Here, magmatic fluids may migrate both through diffuse elastic dilation zones at the tips, and through localized shear zones from the crest. Our results thus suggest how natural observations may be used to constrain the mode of failure occurring underneath a volcano. We discuss several natural examples in this context.

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Section: Methodsmentioning

confidence: 99%

“…In Adeli, common time-integration algorithms like elastic prediction-plastic correction (Ortiz & Simo, 1986) are used to compute the current stress state. More details about numerical aspects can be found in Hassani and Ch ery (1996);Ch ery et al (2001); Cerpa et al (2015).…”

Section: Methodsmentioning

confidence: 99%

Three‐Dimensional Failure Patterns Around an Inflating Magmatic Chamber

Gerbault

Hassani

Lizama

et al. 2018

Geochem Geophys Geosyst

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“…We assume that the lithospheric plates behave as Maxwell viscoelastic solid bodies and that the mantle behaves as a Newtonian fluid (Bonnardot et al, ; Capitanio et al, ; Cerpa et al, , ; Morra & Regenauer‐Lieb, ). The governing equations and our numerical approach have been described in Cerpa et al () and are summarized in the supporting information.…”

Section: Model Setupmentioning

confidence: 99%

Overriding Plate Velocity Control on Surface Topography in 2‐D Models of Subduction Zones

Cerpa

Arcay

2020

Geochem Geophys Geosyst

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We study the dynamically induced flexural topography in subduction numerical mechanical models. We focus on the topographic changes at the overriding plate (OP) surface induced by variations in OP kinematics, particularly when the subducting plate (SP) has a stationary motion after having reached the rigid base of the upper mantle. Our models consist of two viscoelastic plates with free surfaces and an isoviscous mantle. Friction is imposed along the planar subduction interface. We first characterize the main topographic features at a constant OP velocity, using spatial definitions based on geometrical estimations of the volcanic arc position. The models exhibit the formation of a bulge in the forearc area followed landwards by a depression and a smaller second bulge, both bracketing the arc region. The steady-state distance to the trench of these features increases with OP velocity. Their amplitude is affected by the far-field OP tectonic regime that depends on kinematics, and plates and subduction interface strength. We next test the effect of sudden changes in OP velocity. An OP acceleration yields a transient topographic tilt, during which the outer forearc quickly subsides whereas the arc region uplifts, and that is followed by reverse slower motions. An OP slowdown induces opposite motions. The rates of elevation change during the tilt are approximately proportional to velocity variations and mainly sensitive to the SP strength. The rates are higher than 0.1 mm/yr for velocity changes higher than 1 cm/yr. We suggest that topographic accommodations of OP velocity changes should be considered when quantifying nonisostatic topography.

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“…To compute the discretized problem we use the code ADELIM (Cerpa et al 2014(Cerpa et al , 2015 that couples a 2D-FEM solid solver (Hassani et al 1997) . The latter was suggested to control the overriding plate tectonics in present-day subduction zones as it may represent the general interplay between the forces acting on the system.…”

Section: Model Set-upmentioning

confidence: 99%

The interplay between overriding plate kinematics, slab dip and tectonics

Cerpa

Guillaume

Martinod

2018

Geophysical Journal International

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In subductions where the slab stagnates at the 660-km mantle discontinuity, overriding plate kinematics largely controls slab dip and overriding plate tectonics. Although plates kinematics models suggest frequent velocity changes for most plates, the impact of temporal evolution of overriding plate velocity on subduction dynamics has been relatively little addressed. In the present study, we use 2-d numerical models to assess the effects of changes in overriding plate far-field velocity on subduction geometry and on the horizontal stresses transmitted to the overriding plate. When a change in overriding plate velocity arises during slab stagnation, slab dip evolves during a transient period, called adjustment-time, to reach a state in equilibrium with the new boundary conditions. The models predict a dependency of the adjustment-time on the value of velocity change and on several internal parameters (subducting plate density, thickness, and viscosity, and mantle viscosity). We estimate that the adjustment-times may be ∼ 10 − 35 Myrs in Nature, which suggests that most of present-day subduction zones with stagnating slabs might not be at a steady-state. Further, the models predict that changes in overriding plate velocity generate high temporary variations in the state of stresses of the plate.

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Relationship between slab dip and topography segmentation in an oblique subduction zone: Insights from numerical modeling

Cited by 25 publications

References 44 publications

Three‐Dimensional Failure Patterns Around an Inflating Magmatic Chamber

Three‐Dimensional Failure Patterns Around an Inflating Magmatic Chamber

Overriding Plate Velocity Control on Surface Topography in 2‐D Models of Subduction Zones

The interplay between overriding plate kinematics, slab dip and tectonics

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