Geologically current plate motions
TL;DR: MORVEL as discussed by the authors is a new closure-enforced set of angular velocities for the geologically current motions of 25 tectonic plates that collectively occupy 97 per cent of Earth's surface.
Abstract: SUMMARY
We describe best-fitting angular velocities and MORVEL, a new closure-enforced set of angular velocities for the geologically current motions of 25 tectonic plates that collectively occupy 97 per cent of Earth's surface. Seafloor spreading rates and fault azimuths are used to determine the motions of 19 plates bordered by mid-ocean ridges, including all the major plates. Six smaller plates with little or no connection to the mid-ocean ridges are linked to MORVEL with GPS station velocities and azimuthal data. By design, almost no kinematic information is exchanged between the geologically determined and geodetically constrained subsets of the global circuit—MORVEL thus averages motion over geological intervals for all the major plates. Plate geometry changes relative to NUVEL-1A include the incorporation of Nubia, Lwandle and Somalia plates for the former Africa plate, Capricorn, Australia and Macquarie plates for the former Australia plate, and Sur and South America plates for the former South America plate. MORVEL also includes Amur, Philippine Sea, Sundaland and Yangtze plates, making it more useful than NUVEL-1A for studies of deformation in Asia and the western Pacific. Seafloor spreading rates are estimated over the past 0.78 Myr for intermediate and fast spreading centres and since 3.16 Ma for slow and ultraslow spreading centres. Rates are adjusted downward by 0.6–2.6 mm yr−1 to compensate for the several kilometre width of magnetic reversal zones. Nearly all the NUVEL-1A angular velocities differ significantly from the MORVEL angular velocities. The many new data, revised plate geometries, and correction for outward displacement thus significantly modify our knowledge of geologically current plate motions. MORVEL indicates significantly slower 0.78-Myr-average motion across the Nazca–Antarctic and Nazca–Pacific boundaries than does NUVEL-1A, consistent with a progressive slowdown in the eastward component of Nazca plate motion since 3.16 Ma. It also indicates that motions across the Caribbean–North America and Caribbean–South America plate boundaries are twice as fast as given by NUVEL-1A. Summed, least-squares differences between angular velocities estimated from GPS and those for MORVEL, NUVEL-1 and NUVEL-1A are, respectively, 260 per cent larger for NUVEL-1 and 50 per cent larger for NUVEL-1A than for MORVEL, suggesting that MORVEL more accurately describes historically current plate motions. Significant differences between geological and GPS estimates of Nazca plate motion and Arabia–Eurasia and India–Eurasia motion are reduced but not eliminated when using MORVEL instead of NUVEL-1A, possibly indicating that changes have occurred in those plate motions since 3.16 Ma. The MORVEL and GPS estimates of Pacific–North America plate motion in western North America differ by only 2.6 ± 1.7 mm yr−1, ≈25 per cent smaller than for NUVEL-1A. The remaining difference for this plate pair, assuming there are no unrecognized systematic errors and no measurable change in Pacific–North America motion over the past 1–3 Myr, indicates deformation of one or more plates in the global circuit. Tests for closure of six three-plate circuits indicate that two, Pacific–Cocos–Nazca and Sur–Nubia–Antarctic, fail closure, with respective linear velocities of non-closure of 14 ± 5 and 3 ± 1 mm yr−1 (95 per cent confidence limits) at their triple junctions. We conclude that the rigid plate approximation continues to be tremendously useful, but—absent any unrecognized systematic errors—the plates deform measurably, possibly by thermal contraction and wide plate boundaries with deformation rates near or beneath the level of noise in plate kinematic data.
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TL;DR: In this paper, a new type of global plate motion model consisting of a set of continuously-closing topological plate polygons with associated plate boundaries and plate velocities since the break-up of the supercontinent Pangea is presented.
1,519 citations
Cites background from "Geologically current plate motions"
...…(Argus et al., 2010) or a combination of spreading rates, fault azimuths and GPS measurements e.g. NUVEL-1 (DeMets et al., 1990, 2010) and MORVEL (DeMets et al., 2010); (2) Traditional plate tectonicmodels based on the interpretation of the seafloor spreading record and/or paleomagnetic data…...
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...Currently, plate reconstructions fall into three main categories: (1) “Geologically current” models based on present day plate motions from GPS measurements (Argus and Heflin, 1995), space geodesy e.g. GEODVEL (Argus et al., 2010) or a combination of spreading rates, fault azimuths and GPS measurements e.g. NUVEL-1 (DeMets et al., 1990, 2010) and MORVEL (DeMets et al., 2010); (2) Traditional plate tectonicmodels based on the interpretation of the seafloor spreading record and/or paleomagnetic data to reconstruct the ocean basins, continents and terranes within an absolute reference framework (Scotese et al., 1988; Scotese, 1991; Golonka and Ford, 2000; Schettino and Scotese, 2005; Golonka, 2007; Müller et al., 2008b); (3) Coupled geodynamic–plate models, whichmodel plate boundary locations andmantle density heterogeneity to predict past and/or present plate motions (Hager and O'Connell, 1981; Lithgow-Bertelloni and Richards, 1998; Conrad and Lithgow-Bertelloni, 2002; Stadler et al., 2010)....
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...…Heflin, 1995), space geodesy e.g. GEODVEL (Argus et al., 2010) or a combination of spreading rates, fault azimuths and GPS measurements e.g. NUVEL-1 (DeMets et al., 1990, 2010) and MORVEL (DeMets et al., 2010); (2) Traditional plate tectonicmodels based on the interpretation of the seafloor…...
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Journal Article•
TL;DR: In this article, a digital age grid of the ocean floor with a grid node interval of 6 arc min using a self-consistent set of global isochrons and associated plate reconstruction poles was created.
Abstract: We have created a digital age grid of the ocean floor with a grid node interval of 6 arc min using a self-consistent set of global isochrons and associated plate reconstruction poles. The age at each grid node was determined by linear interpolation between adjacent isochrons in the direction of spreading. Ages for ocean floor between the oldest identified magnetic anomalies and continental crust were interpolated by estimating the ages of passive continental margin segments from geological data and published plate models. We have constructed an age grid with error estimates for each grid cell as a function of (1) the error of ocean floor ages identified from magnetic anomalies along ship tracks and the age of the corresponding grid cells in our age grid, (2) the distance of a given grid cell to the nearest magnetic anomaly identification, and (3) the gradient of the age grid: i.e., larger errors are associated with high age gradients at fracture zones or other age discontinuities. Future applications of this digital grid include studies of the thermal and elastic structure of the lithosphere, the heat loss of the Earth, ridge-push forces through time, asymmetry of spreading, and providing constraints for seismic tomography and mantle convection models.
752 citations
TL;DR: Detailed geophysical measurements reveal features of the 2011 Tohoku-Oki megathrust earthquake and suggest the need to consider the potential for a future large earthquake just south of this event.
Abstract: Geophysical observations from the 2011 moment magnitude (M_w) 9.0 Tohoku-Oki, Japan earthquake allow exploration of a rare large event along a subduction megathrust. Models for this event indicate that the distribution of coseismic fault slip exceeded 50 meters in places.
Sources of high-frequency seismic waves delineate the edges of the
deepest portions of coseismic slip and do not simply correlate with the
locations of peak slip. Relative to the M_w 8.8 2010 Maule, Chile
earthquake, the Tohoku-Oki earthquake was deficient in high-frequency
seismic radiation-a difference that we attribute to its relatively
shallow depth. Estimates of total fault slip and surface secular strain
accumulation on millennial time scales suggest the need to consider the
potential for a future large earthquake just south of this event.
691 citations
TL;DR: The Global Strain Rate Model (GSRM v.2.1) as mentioned in this paper is a new global model of plate motions and strain rates in plate boundary zones constrained by horizontal geodetic velocities.
Abstract: We present a new global model of plate motions and strain rates in plate boundary zones constrained by horizontal geodetic velocities. This Global Strain Rate Model (GSRM v.2.1) is a vast improvement over its predecessor both in terms of amount of data input as in an increase in spatial model resolution by factor of ∼2.5 in areas with dense data coverage. We determined 6739 velocities from time series of (mostly) continuous GPS measurements; i.e., by far the largest global velocity solution to date. We transformed 15,772 velocities from 233 (mostly) published studies onto our core solution to obtain 22,511 velocities in the same reference frame. Care is taken to not use velocities from stations (or time periods) that are affected by transient phenomena; i.e., this data set consists of velocities best representing the interseismic plate velocity. About 14% of the Earth is allowed to deform in 145,086 deforming grid cells (0.25° longitude by 0.2° latitude in dimension). The remainder of the Earth's surface is modeled as rigid spherical caps representing 50 tectonic plates. For 36 plates we present new GPS-derived angular velocities. For all the plates that can be compared with the most recent geologic plate motion model, we find that the difference in angular velocity is significant. The rigid-body rotations are used as boundary conditions in the strain rate calculations. The strain rate field is modeled using the Haines and Holt method, which uses splines to obtain an self-consistent interpolated velocity gradient tensor field, from which strain rates, vorticity rates, and expected velocities are derived. We also present expected faulting orientations in areas with significant vorticity, and update the no-net rotation reference frame associated with our global velocity gradient field. Finally, we present a global map of recurrence times for Mw=7.5 characteristic earthquakes.
608 citations
Cites background or methods or result from "Geologically current plate motions"
...Of the 50 plates, 36 angular velocities were estimated from the GPS velocities in our compilation (mostly ones derived by ourselves), 6 were taken from PB2002 [Bird, 2003] and 8 were taken from MORVEL [DeMets et al., 2010]....
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...Our rotation rate for Nazca is significantly slower than the MORVEL estimate, indicating the continued slow-down of the Nazca plate since 0.78 Ma [DeMets et al., 2010]....
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...The Bering, Capricorn, Lwandle are part of the MORVEL plate motion model [DeMets et al., 2010], although MORVEL did not have a rotation rate for Bering, which we estimated from the GPS data....
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...3) Cocos: We used the MORVEL angular velocity for Cocos [DeMets et al., 2010]....
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...We therefore adopted the rotation from MORVEL [DeMets et al., 2010]....
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TL;DR: The NNR-MORVEL56 set of geologically current relative plate angular velocities is derived in this article, which is the first set of angular veloci measured relative to the unique reference frame in which there is no net rotation of the lithosphere.
Abstract: NNR-MORVEL56, which is a set of angular velocities of 56 plates relative to the unique reference frame in which there is no net rotation of the lithosphere, is determined. The relative angular velocities of 25 plates constitute the MORVEL set of geologically current relative plate angular velocities; the relative angular velocities of the other 31 plates are adapted from Bird (2003). NNR-MORVEL, a set of angular velocities of the 25 MORVEL plates relative to the no-net rotation reference frame, is also determined. Incorporating the 31 plates from Bird (2003), which constitute 2.8% of Earth's surface, changes the angular velocities of the MORVEL plates in the no-net-rotation frame only insignificantly, but provides a more complete description of globally distributed deformation and strain rate. NNR-MORVEL56 differs significantly from, and improves upon, NNR-NUVEL1A, our prior set of angular velocities of the plates relative to the no-net-rotation reference frame, partly due to differences in angular velocity at two essential links of the MORVEL plate circuit, Antarctica-Pacific and Nubia-Antarctica, and partly due to differences in the angular velocities of the Philippine Sea, Nazca, and Cocos plates relative to the Pacific plate. For example, the NNR-MORVEL56 Pacific angular velocity differs from the NNR-NUVEL1A angular velocity by a vector of length 0.039 ± 0.011° a−1 (95% confidence limits), resulting in a root-mean-square difference in velocity of 2.8 mm a−1. All 56 plates in NNR-MORVEL56 move significantly relative to the no-net-rotation reference frame with rotation rates ranging from 0.107° a−1 to 51.569° a−1.
458 citations
Cites background from "Geologically current plate motions"
...[2] MORVEL is a set of geologically current relative plate angular velocities for 25 major plates covering 97% of the surface of the Earth [DeMets et al., 2010]....
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...Differences in angular velocity among the 36 plate pairs are vectors ranging in length from 0.007°Ma−1 to 0.105° Ma−1, with the median difference having a length of 0.053° Ma−1, which corresponds to 5.9 mm a−1 or less along Earth’s surface [DeMets et al., 2010]....
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...Thus, in MORVEL the angular velocity of the plates of the Pacific ocean basin (Pacific, Nazca, Cocos) relative to the surrounding continental plates (Eurasia, North America, South America) depend mainly on the plate circuit North America‐Nubia‐Antarctica‐ Pacific [DeMets et al., 2010, Figure 2]....
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References
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TL;DR: In this paper, a digital bathymetric map of the oceans with a horizontal resolution of 1 to 12 kilometers was derived by combining available depth soundings with high-resolution marine gravity information from the Geosat and ERS-1 spacecraft.
Abstract: A digital bathymetric map of the oceans with a horizontal resolution of 1 to 12 kilometers was derived by combining available depth soundings with high-resolution marine gravity information from the Geosat and ERS-1 spacecraft. Previous global bathymetric maps lacked features such as the 1600-kilometer-long Foundation Seamounts chain in the South Pacific. This map shows relations among the distributions of depth, sea floor area, and sea floor age that do not fit the predictions of deterministic models of subsidence due to lithosphere cooling but may be explained by a stochastic model in which randomly distributed reheating events warm the lithosphere and raise the ocean floor.
4,433 citations
TL;DR: The Generic Mapping Tools (GMT) is introduced, which is a free, public domain software package that can be used to manipulate columns of tabular data, time series, and gridded data sets and to display these data in a variety of forms ranging from simple x-y plots to maps and color, perspective, and shaded-relief illustrations.
Abstract: When creating camera-ready figures, most scientists are familiar with the sequence of raw data → processing → final illustration and with the spending of large sums of money to finalize papers for submission to scientific journals, prepare proposals, and create overheads and slides for various presentations. This process can be tedious and is often done manually, since available commercial or in-house software usually can do only part of the job.
To expedite this process, we introduce the Generic Mapping Tools (GMT), which is a free, public domain software package that can be used to manipulate columns of tabular data, time series, and gridded data sets and to display these data in a variety of forms ranging from simple x-y plots to maps and color, perspective, and shaded-relief illustrations. GMT uses the PostScript page description language, which can create arbitrarily complex images in gray tones or 24-bit true color by superimposing multiple plot files. Line drawings, bitmapped images, and text can be easily combined in one illustration. PostScript plot files are device-independent, meaning the same file can be printed at 300 dots per inch (dpi) on an ordinary laserwriter or at 2470 dpi on a phototypesetter when ultimate quality is needed. GMT software is written as a set of UNIX tools and is totally self contained and fully documented. The system is offered free of charge to federal agencies and nonprofit educational organizations worldwide and is distributed over the computer network Internet.
4,128 citations
TL;DR: A global plate motion model, named NUVEL-1, which describes current plate motions between 12 rigid plates is described, with special attention given to the method, data, and assumptions used as discussed by the authors.
Abstract: A global plate motion model, named NUVEL-1, which describes current plate motions between 12 rigid plates is described, with special attention given to the method, data, and assumptions used Tectonic implications of the patterns that emerged from the results are discussed It is shown that wide plate boundary zones can form not only within the continental lithosphere but also within the oceanic lithosphere; eg, between the Indian and Australian plates and between the North American and South American plates Results of the model also suggest small but significant diffuse deformation of the oceanic lithosphere, which may be confined to small awkwardly shaped salients of major plates
3,409 citations
TL;DR: In this article, the optimal recalibration of NUVEL-1 is proposed to multiply the angular velocities by a constant, α, of 0.9562, which is a compromise among slightly different calibrations appropriate for slow, medium, and fast rates of seafloor spreading.
Abstract: Recent revisions to the geomagnetic time scale indicate that global plate motion model NUVEL-1 should be modified for comparison with other rates of motion including those estimated from space geodetic measurements. The optimal recalibration, which is a compromise among slightly different calibrations appropriate for slow, medium, and fast rates of seafloor spreading, is to multiply NUVEL-1 angular velocities by a constant, α, of 0.9562. We refer to this simply recalibrated plate motion model as NUVEL-1A, and give correspondingly revised tables of angular velocities and uncertainties. Published work indicates that space geodetic rates are slower on average than those calculated from NUVEL-1 by 6±1%. This average discrepancy is reduced to less than 2% when space geodetic rates are instead compared with NUVEL-1A.
3,359 citations
01 Jan 1988
TL;DR: In this paper, a new global model (NUVEL-1) was proposed to describe the geologically current motion between 12 assumed-rigid plates by inverting plate motion data.
Abstract: SUMMARY
We determine best-fitting Euler vectors, closure-fitting Euler vectors, and a new global model (NUVEL-1) describing the geologically current motion between 12 assumed-rigid plates by inverting plate motion data we have compiled, critically analysed, and tested for self-consistency. We treat Arabia, India and Australia, and North America and South America as distinct plates, but combine Nubia and Somalia into a single African plate because motion between them could not be reliably resolved. The 1122 data from 22 plate boundaries inverted to obtain NUVEL-1 consist of 277 spreading rates, 121 transform fault azimuths, and 724 earthquake slip vectors. We determined all rates over a uniform time interval of 3.0m.y., corresponding to the centre of the anomaly 2A sequence, by comparing synthetic magnetic anomalies with observed profiles. The model fits the data well. Unlike prior global plate motion models, which systematically misfit some spreading rates in the Indian Ocean by 8–12mm yr−1, the systematic misfits by NUVEL-1 nowhere exceed ∼3 mm yr−1. The model differs significantly from prior global plate motion models. For the 30 pairs of plates sharing a common boundary, 29 of 30 P071, and 25 of 30 RM2 Euler vectors lie outside the 99 per cent confidence limits of NUVEL-1. Differences are large in the Indian Ocean where NUVEL-1 plate motion data and plate geometry differ from those used in prior studies and in the Pacific Ocean where NUVEL-1 rates are systematically 5–20 mm yr−1 slower than those of prior models. The strikes of transform faults mapped with GLORIA and Seabeam along the Mid-Atlantic Ridge greatly improve the accuracy of estimates of the direction of plate motion. These data give Euler vectors differing significantly from those of prior studies, show that motion about the Azores triple junction is consistent with plate circuit closure, and better resolve motion between North America and South America. Motion of the Caribbean plate relative to North or South America is about 7 mm yr−1 slower than in prior global models. Trench slip vectors tend to be systematically misfit wherever convergence is oblique, and best-fitting poles determined only from trench slip vectors differ significantly from their corresponding closure-fitting Euler vectors. The direction of slip in trench earthquakes tends to be between the direction of plate motion and the normal to the trench strike. Part of this bias may be due to the neglect of lateral heterogeneities of seismic velocities caused by cold subducting slabs, but the larger part is likely caused by independent motion of fore-arc crust and lithosphere relative to the overriding plate.
3,328 citations