Slab pull and the seismotectonics of subducting lithosphere

Spence, William

doi:10.1029/rg025i001p00055

Cited by 126 publications

(95 citation statements)

References 124 publications

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“…The force per unit length related to a general slab force is not easy to quantify also because it depends on various parameters such as the dip angle, the plate velocity, the penetration depth and probably more. In a first approximation pure slab pull forces have been estimated to be in the range of 5-15×10 12 N/m (Forsyth and Uyeda, 1975;Spence, 1987;Turcotte and Schubert, 2002). More recent simulations however, have suggested that the net slab pull force is of order 4-6×10 12 N/m (Bird et al, 2008;Schellart, 2004) which is in agreement with our results.…”

Section: Discussionsupporting

confidence: 83%

Quantifying the forces needed for the rapid change of Pacific plate motion at 6Ma

Austermann¹,

Ben‐Avraham²,

Bird³

et al. 2011

Earth and Planetary Science Letters

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Editor: Y. Ricard Keywords:Pacific plate motion plate driving forces slab detachment oceanic plateau collision northern Melanesian arc Studies have documented several rapid changes along the Pacific-North American, Pacific-Antarctic and Pacific-Australian plate boundaries in latest Miocene to earliest Pliocene time consistent with a sudden clockwise rotation of Pacific plate velocity relative to hotspots during this period. We test the hypothesis that this change in plate motion was initiated by cessation of subduction along the northern Melanesian arc due to the collision between the arc and the Ontong Java plateau. This hypothesis has long been formulated but never tested quantitatively. We use a geomechanical model of the lithosphere to determine the changes in plate boundary forces that are necessary to obtain the observed change in the Pacific plate motion. Our model results show that the change in motion can be explained by a clockwise rotation of the slab-related (basal-strength) component of plate driving force. The change of slab-related force from a post-6 Ma to a pre-6 Ma setting is perpendicular to the arc and points towards the Australian plate. The force per unit length is in the range of currently accepted values for subduction zones. Since there have been no other relevant changes at subduction zones along the Pacific plate boundary during the latest Miocene, we relate this change in slab-related force to the former southward-dipping Pacific plate slab along the northern Melanesian arc system which is now detached. Our model results suggest that rapid changes in plate motion can be triggered by slab detachment, with consequences for plate boundary processes even at great distances from the event.

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Section: Discussionsupporting

confidence: 83%

Quantifying the forces needed for the rapid change of Pacific plate motion at 6Ma

Austermann¹,

Ben‐Avraham²,

Bird³

et al. 2011

Earth and Planetary Science Letters

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“…The origin of the Strait of Sicily rift is not fully understood, although the roughly north-south extension, about parallel to the coeval strike of the subducted Tyrrhenian slab, suggests the possible activity of a slab pull force (Spence 1987). As the Maghrebian fold-and-thrust belt encroached the continental lithosphere of the African margin, the arrival at the subduction zone of the buoyant continental lithosphere slowed down the subduction rate, maximizing the effect of slab pull on the subducted African lithosphere ( Fig.…”

Section: Geological and Geophysical Evidence For A Trench-parallel Tementioning

confidence: 99%

Evolution of the southern Tyrrhenian slab tear and active tectonics along the western edge of the Tyrrhenian subducted slab

Argnani

2009

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The evolution of the southern Tyrrhenian subduction has been possibly controlled by distinct episodes of slab break-off as indicated by a critical review of the geological literature and by the analysis of purposely acquired multichannel seismic profiles. Within the proposed interpretation the first episode occurred from 8.5 to 4.0 Ma and affected the segment of the slab located in the Sardinia Channel, causing the abandonment of the Adventure thrust front in western Sicily. The second episode occurred between 2.5 and 1.6 Ma, affecting the segment of slab located north of Sicily, and was preceeded by rifting in the Strait of Sicily. The space and time location of these episodes appear controlled by discontinuities pre-existing within the subducted African plate that trend at high angle to the advancing subduction front. These discontinuities delimit segment of subducted slab that can be affected by slab break-off and can act as wayouts for magma and mantle derived He. The major of these discontinuities, the Malta Escarpment, has been reactivated in the Quaternary as a trench-perpendicular tear (STEP faults). Ultimately, the hierarchy in strength of these trench-perpendicular features could have affected the timing and amount of trench retreat and backarc opening.

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“…plates, as reviewed recently by Spence [1987], does, however, allow some characterization of these time average stresses. For example, the presumed dominance of slab pull as a driving force suggests that a" will correspond to extensional stresses in regions of the plate downdip from the thrust contact zone, that is, in the subducting slab zone of Figure 11.…”

Section: Consideration Of the Gravitational Loading Of Subductingmentioning

confidence: 99%

Stress transfer and seismic phenomena in coupled subduction zones during the earthquake cycle

Dmowska¹,

Rice²,

Lovison³

et al. 1988

J. Geophys. Res.

144

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An elementary mechanical model of a coupled subduction zone is presented. It is used to study the transfer of extensional stresses along the underthrusting plate, and shear stress interactions between the plate itself and its thrust contact zone with the overriding plate, during the earthquake cycle. The model assumes an elastic plate which deforms one dimensionally, has shear drag interactions (treated approximately by the Elsasser procedure) with a Maxwellian viscoelastic mantle, and is subject to steady gravitational sinking forces. Great thrust earthquakes are simulated as sudden stress-relieving displacements at the contact zone between the slab and overriding plate. The model allows analysis of the spaceand time-variable stresses in the main thrust zone, the adjacent oceanic plate, and the subducting slab over each earthquake cycle. Stress variations leading to outer-rise events are discussed, as well as stress changes responsible for intraplate seismicity downdip from the main thrust zone, based on simulations of periodic great earthquakes. The results of simulated slow progression of deformation (slip) from below into the thrust contact zone are also presented. Such preslip, occurring over a time scale that is small in comparison with the whole seismic cycle (e.g., of the order of a tenth or so), is shown to transiently slow the rate of buildup of, or even relieve, extensional stresses in the slab. In the absence of preslip those stresses build up steadily in time during the latter part of the cycle. The results have implications for induction of sesimic quiescence as well as for explaining patterns of seismicity in relation to spatial position along the underthrusting plate and to time throughout the cycle. Correlations are reported between the model simulations and seismicity observations from coupled subduction zones around the world. The observations include tensional outer-rise events after large subduction earthquakes and compressional ones in the latter parts of the cycle, normal (tensional) intraplate earthquakes preceding the main thrust events and positioned downdip from the thrust zones, and interlaced periods of seismic activity in the lower part of the main thrust zone and in the descending slab. INTRODUCTIONThe concept of large earthquakes repeating themselves along coupled subduction zones has long been recognized [Fedotov, 1965] As a result of the episodic motion of the subducting slab, of which the upper part is locked and slides only in the main event, and of the gravitationally driven sinking of the lower parts of the slab, stresses pulsate in time throughout the cycle, with stress transfer interactions occurring between different regions of the slab and its surroundings. We present here an elementary model of such stress accumulation and transfer. Before doing that we briefly review the observational basis for such modeling, using our own observations as well as those reported by others and concentrating on the interactions between the thrust contact zone and the subducting plate. IN...

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Slab pull and the seismotectonics of subducting lithosphere

Cited by 126 publications

References 124 publications

Quantifying the forces needed for the rapid change of Pacific plate motion at 6Ma

Quantifying the forces needed for the rapid change of Pacific plate motion at 6Ma

Evolution of the southern Tyrrhenian slab tear and active tectonics along the western edge of the Tyrrhenian subducted slab

Stress transfer and seismic phenomena in coupled subduction zones during the earthquake cycle

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