Rotation and plate locking at the Southern Cascadia Subduction Zone

McCaffrey, Robert J.; Long, Maureen D.; Goldfinger, Chris; Zwick, Peter C.; Nábělek, J.; Johnson, Cheryl K.; Smith, Curt

doi:10.1029/2000gl011768

Cited by 161 publications

(181 citation statements)

References 18 publications

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“…The JDF-NA pole determined by Riddihough (1984) leads to more oblique convergence for the entire margin and more pronounced along-strike variations of the convergence direction and rate as compared to NUVEL-1. Miller et al (2001) and McCaffrey et al (2000) both used a JDF-NA pole derived from a Pacific-NA pole newly determined by DeMets and Dixon (1999) and the Pacific-JDF pole of NUVEL-1a (DeMets et al, 1994;Wilson, 1993). This most recent pole predicts a convergence pattern very similar to that predicted by Riddihough, but with smaller convergence rates (Fig.…”

Section: Model With Variable Convergence Along Strikementioning

confidence: 99%

Three-dimensional viscoelastic interseismic deformation model for the Cascadia subduction zone

Wang

Dragert

et al. 2014

Earth Planet Sp

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Contemporary deformation of the Cascadia forearc consists of an elastic interseismic strain build-up as part of the subduction earthquake deformation "cycle" and a secular deformation primarily in the form of arc-parallel translation and clockwise rotation of forearc blocks. A three-dimensional (3-D) elastic dislocation model, constrained by vertical deformation data, was developed previously to study the interseismic deformation. In this study, we develop a 3-D viscoelastic finite element model for the Cascadia subduction zone to study the temporal and spatial variations of interseismic deformation, and we compare the model results primarily with horizontal geodetic deformation observations. The model has an elastic lithosphere/slab and a viscoelastic mantle which has a viscosity of 10 19 Pa s as constrained by recent postglacial rebound analyses. For comparison, we adopt a seismogenic zone geometry that was used in the previous elastic dislocation model, and we test the effects of different estimates of relative plate motion on the model predictions. Interseismic deformation is simulated by assigning a backslip rate to the locked zone of the subduction fault, preceded by an earthquake rupture of the same zone. Based on preliminary model results, we draw the following conclusions: (1) The deformation rate decreases through the interseismic period. A seaward motion is predicted for inland sites early in the interseismic period, an effect of postseismic creep of the mantle. (2) Model strain rates 300 years after the earthquake are consistent with the observed values, regardless of the plate motion models used. The horizontal velocities in northern Cascadia decrease landward at a slower rate than predicted by the elastic dislocation model, providing a better fit to observations. (3) Oblique subduction causes strain partitioning. As a result, the direction of local maximum contraction is much less oblique than plate convergence. The northerly direction of the GPS velocities in southern Cascadia represent a northward translation of the forearc. The secular deformation of the forearc may be partially accommodated through earthquake deformation cycles, but it may be better modeled as a process independent of the earthquake cycle.

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Section: Model With Variable Convergence Along Strikementioning

confidence: 99%

Three-dimensional viscoelastic interseismic deformation model for the Cascadia subduction zone

Wang

Dragert

et al. 2014

Earth Planet Sp

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“…Geodesy also enables characterization of upper-plate sliver or block motions that may result from oblique convergence. This is now recognized as quite common, and it must be accounted for when evaluating the megathrust strain energy budget (e.g., McCaffrey et al, 2000;Wallace et al, 2004;La Femina et al, 2009). Precursory sliding near a future hypocenter, postseismic slip around main-shock rupture zones, relocking of a ruptured zone, and viscoelastic deformation after an event are processes that have been sensed by onshore and, increasingly, offshore geodetic measurements, greatly expanding our view into the seismic strain accumulation and release process and the ways in which relative plate motion is accommodated across the entire megathrust (e.g., Ito et al, 2013;Yokota et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Subduction zone megathrust earthquakes

2018

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Subduction zone megathrust faults host Earth's largest earthquakes, along with multitudes of smaller events that contribute to plate convergence. An understanding of the faulting behavior of megathrusts is central to seismic and tsunami hazard assessment around subduction zone margins. Cumulative sliding displacement across each megathrust, which extends from the trench to the downdip transition to interplate ductile deformation, is accommodated by a combination of rapid stick-slip earthquakes, episodic slow-slip events, and quasi-static creep. Megathrust faults have heterogeneous frictional properties that contribute to earthquake diversity, which is considered here in terms of regional variations in maximum recorded magnitudes, Gutenberg-Richter b values, earthquake productivity, and cumulative seismic moment depth distributions for the major subduction zones. Great earthquakes on megathrusts occur in irregular cycles of interseismic strain accumulation, foreshock activity, main-shock rupture, postseismic slip, viscoelastic relaxation, and fault healing, with all stages now being captured by geophysical monitoring. Observations of depth-dependent radiation characteristics, large earthquake slip distributions, variations in rupture velocities, radiated energy and stress drop, and relationships to aftershock distributions and afterslip are discussed. Seismic sequences for very large events have some degree of regularity within subduction zone segments, but this can be complicated by supercycles of intermittent huge ruptures that traverse segment boundaries. Factors influencing variability of large megathrust ruptures, such as large-scale plate structure and kinematics, presence of sediments and fluids, lower-plate bathymetric roughness, and upper-plate structure, are discussed. The diversity of megathrust failure processes presents a suite of natural hazards, including earthquake shaking, submarine slumping, and tsunami generation. Improved monitoring of the offshore environment is needed to better quantify and mitigate the threats posed by megathrust earthquakes globally.

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“…The northwest directed shear at the newly formed San Andreas fault system leads to complex shearing and rotation of blocks in the fault system [Atwater and Stock, 1988] as well as opening and westward extension of the Basin and Range due to gravitational collapse [Sonder and Jones, 1999;Wernicke, 1992]. Shear associated with Pacific -North America plate motions affects deformation at least as far inland as the western Basin and Range [Meade and Hager, 2005;Thatcher, 2003], while subduction of the Juan de Fuca plate below the overriding North America plate causes contraction in the Pacific Northwest [Zoback and Zoback, 1991;McCaffrey et al, 2000;Wang et al, 2003;McCaffrey et al, 2007].…”

Section: Discussionmentioning

confidence: 99%

“…The influence of shear stresses associated with the San Andreas fault extend eastward into the western Basin-Range [Thatcher, 2003], leading to a regime of oblique strike-slip faulting in the Walker Lane seismic belt in western Nevada (Figure 1). Further north, stress interaction of the subducting Juan de Fuca plate beneath the overriding North America plate produces an eastward component of ground motion associated with the Columbia Plateau at least as far as eastern Washington and Oregon [McCaffrey et al, 2000Wang et al, 2003].…”

Section: Late Cenozoic Tectonics Of the Western Us Interiormentioning

confidence: 99%

“…[10] At large scales, North America -Pacific interplate interactions produce right-lateral shear deformation on the San Andreas and subsidiary faults, while North AmericaJuan de Fuca interactions result in oblique convergence in the Pacific Northwest [e.g., Atwater, 1970;Gan et al, 2000;McCaffrey et al, 2000]. The influence of shear stresses associated with the San Andreas fault extend eastward into the western Basin-Range [Thatcher, 2003], leading to a regime of oblique strike-slip faulting in the Walker Lane seismic belt in western Nevada (Figure 1).…”

Section: Late Cenozoic Tectonics Of the Western Us Interiormentioning

confidence: 99%

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Intraplate deformation and microplate tectonics of the Yellowstone hot spot and surrounding western U.S. interior

Puskas¹,

Smith²

2009

J. Geophys. Res.

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[1] Contemporary deformation of the Yellowstone hot spot and surrounding western United States is analyzed using tectonic microplate modeling, employing constraints from GPS observations corrected for postseismic deformation of M7+ earthquakes, fault slip rates, and earthquake focal mechanisms. We focus primarily on the kinematics of the Yellowstone hot spot and the eastern Snake River Plain volcanic field (ESRP), and secondarily on Basin-Range and Columbia Plateau provinces. Our results reveal southwest motion of the Yellowstone Plateau, excluding localized volcanic deformation, at 0.9 ± 0.1 mm/a that decreases to 0.8 ± 0.1 mm/a in the ESRP block. The southwest to west motion of the Yellowstone-ESRP introduces shear in the northern Rocky Mountain block, which is translating east at 0.78 ± 0.08 mm/a. There is <0.5 mm/a differential motion between the ESRP and the block at its northern boundary and none at the southern boundary. The eastern Basin-Range block moves west at 3.0 ± 0.1 to 4.6 ± 0.1 mm/a, while velocities of the western Basin-Range microplates rotate to a northwest direction, accompanied by a transition from normal to oblique shear deformation. Columbia Plateau block velocities are notably eastward, an effect enhanced by postseismic relaxation following the M9 1700 Cascadia subduction zone paleoearthquake. This study reveals that the overall motion of the western United States is characterized by clockwise rotation, with westward extension and northwest shear in the Basin-Range province, northeast to east contraction in the Columbia Plateau, and southwest extension of the YellowstoneSnake River Plain block that is driven by the high gravitational potential of the Yellowstone swell.Citation: Puskas, C. M., and R. B. Smith (2009), Intraplate deformation and microplate tectonics of the Yellowstone hot spot and surrounding western U.S. interior,

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Rotation and plate locking at the Southern Cascadia Subduction Zone

Cited by 161 publications

References 18 publications

Three-dimensional viscoelastic interseismic deformation model for the Cascadia subduction zone

Three-dimensional viscoelastic interseismic deformation model for the Cascadia subduction zone

Subduction zone megathrust earthquakes

Intraplate deformation and microplate tectonics of the Yellowstone hot spot and surrounding western U.S. interior

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