Overview:

This program is for the calculation of tectonic plate motion at any location on Earth using one or more plate motion models. You can specify:

• position in geographic or WGS-84 XYZ coordinates
• the tectonic plate (default is auto selection)
• plate motion model (default is GSRM v1.2)
• motion referenced either to a fixed plate or the NNR (no-net-rotation) frame of the selected model (default is NNR)
• optional site name
• multiple point entry in geographic or xyz coordinates
• for advanced users: define your own pole of attributed motion and/or your own reference pole
• output format style (HTML table, GMT psvelo)

The possible plate motion models are:

(Please see full reference citations at the end of this page.) The velocity uncertainties of each model are not taken into consideration and are assumed to be zero.

Usage:

It's easier than it looks. For a single point, just enter the longitude and latitude and hit Submit. In this case, your point will then be located using the Auto plate selection, with motion referenced to the NNR frame of the GSRM v 1.2 model. If, however, you feel that your coordinate is in some other plate or subplate (see Notes below), you can override the Auto plate selection and select some other plate and then resubmit. Likewise, if you want the motion relative to some other fixed plate, overide NNR as a reference. If you have coordinates in WGS-84 XYZ (cartesian) values, you can use those values as input. Try different models, or look at results from all models.

Once you get the feel for a single point entry, you can try multiple point entry. There are three important things to remember. First, each set of values for a location, whether in geographic or cartesian coordinates, must be separated from the others by a comma. Second, if you are using geographic coordinates, a height value (even if zero) must be supplied. Anything after the third coordinate (height if geographic, Z if cartesian) and before the comma is taken an optional site name. So, for geographic multiple point entry, your entry could look like:

-105.27 43.98 0 test site1,
-104.45 42.02 0,
-107.23 45.56 0,

Third, either all the multiple points need to be on the same tectonic plate, or else you should use the Auto plate selection, though (see Notes below) this means that the auto plate selection will only find the plates defined for NUVEL 1A.

Results for the poles, 90°N and 90°S, will be correct but the east and north components of the velocity vector depend on the longitude given. To convince yourself, step back from the pole a little, say, to 89.99°N or 89.99°S, at the same longitude and repeat the calculation.

Notes:

If selected, the Euler rotation pole parameters of NNR-NUVEL-1 by Argus and Gordon [1991] and NUVEL-1A by DeMets et al. [1994] are used. NUVEL-1A rotation poles are generally the same as NUVEL-1, except that the rate of rotations are on average about 4.4% slower due to an adjustment to the magnetic anomaly time scale. For the Juan de Fuca and Philippine Sea poles of NUVEL-1A, the more recent recalibrated pole values are used.

Care must be taken when comparing a specified plate between different models, because which plates are defined or have defined rotation poles varies from model to model. The Auto plate selection of the calculator uses 15 plate boundaries corresponding to the NUVEL 1A model (bold in the table below). You can get ASCII files of these boundaries from http://jules.unavco.org/GMT/. Using the table below, then, the Antarctica plate (AN) of NUVEL 1 corresponds to the combined Antarctica (AN) and Scotia (ST) plate of NUVEL 1A. Likewise, the combined Australia (AU) and Capricorn (CP) plates of the GSRM correspond to the Australia (AU) plate of the other models. In certain models, some plates have no defined pole of rotation, e.g. the India (IN) plate in the APKIM model. This leads to two important points:

Caveat emptor!   If you or the Auto plate selection selects a plate for your location that is not accounted for in the selected model, that plate is assumed to have a zero pole of rotation. Likewise, if you select a fixed-plate reference where that plate is not accounted for in the selected model, that fixed-plate reference is assumed to have a zero pole of rotation with respect to the NNR frame. Therefore, make sure that the selected plate and fixed-plate reference (if not NNR) are defined for the selected model before using the results.

Another subtle point is that the plate motion models apply only on those places on a plate undergoing rigid body rotation — which is especially important to keep in mind for the GSRM. If you are attempting to model the motion in a plate boundary zone which is undergoing strain deformation (i.e. not just a simple rigid body rotation), then the rigid body motion model is only an approximation to the actual motion.

And what is a "no-net_rotation" (aka NNR) frame? By definition it is the reference frame for a given model of plate motion that yields zero for the integral of the vector cross-product v x r over the surface of the Earth.

HS2-NUVEL1A and HS3-NUVEL1A: Technically these models are not published in a NNR frame, since these represent the plate motions relative to fixed "hotspot" frames. In order to make this calculator function more logically, however, these models are also provided here in a NNR frame whereby the following "hotspot frame - NNR frame" rotations have been applied:

References:

Altamimi, Z., P. Sillard, and C. Boucher, ITRF2000: A new release of the International Terrestrial Reference Frame for earth science applications, J. Geophys. Res., 107(B10), 2214, doi:10.1029/2001JB000561, 2002; see also tn31_270.pdf.

Argus, D.F. and R.G. Gordon, No-net-rotation model of current plate velocities incorporating plate motion model NUVEL-1, Geophys. Res. Lett., 18, 2039-2042, 1991.

DeMets, C., R.G. Gordon, D.F. Argus, and S. Stein, Current plate motions, Geophys. J. Int., 101, 425-478, 1990.

DeMets, C., R.G. Gordon, D.F. Argus, and S. Stein, Effect of recent revisions to the geomagnetic reversal time scale on estimates of current plate motions, Geophys. Res. Lett., 21, 2191-2194, 1994.

Drewes, H., Combination of VLBI, SLR, and GPS determined station velocities for actual plate kinematic and crustal deformation models, Geodynamics, M. Feissel (Ed.), IAG Symposia, Springer, 1998.

Drewes, H., APKIM2000.0 (Actual Plate Kinematic Model).

Drewes, H., and D. Angermann, The Actual Plate Kinematic and Crustal Deformation Model 2000 (APKIM2000) as a Geodetic Reference System, AIG 2001 Scientific Assembly, Budapest, 2-8 Sept 2001; see also DS_APKIM.pdf.

Gripp, A.E., and R.G. Gordon, Current plate velocities relative to the hopspots incorporating the NUVEL-1 global plate motion model, Geophys. Res. Lett., 17, 1109-1112, 1990; see also Model HS2-NUVEL 1A (motion of plates relative to hotspots averaged over last 3.2 Myr).

Gripp, A.E., and R.G. Gordon, Young tracks of hotspots and current plate velocities, Geophys. J. Int., 150, 321-361, 2002; see also Model HS3-NUVEL 1A (motion of plates relative to hotspots averaged over last 5.8 Myr).

Kreemer, C., Global Strain Rate Map Project; Corné Kreemer kindly provided NNR poles of rotation for version 1.2, May 2004; see also Kreemer, C., W.E. Holt, and A.J. Haines, An integrated global model of present-day plate motions and plate boundary deformation, Geophys. J. Int., 154, 8-34, 2003.

Prawirodirdjo, L., and Y. Bock, Instantaneous global plate motion model from 12 years of continuous GPS observations, J. Geophys. Res., 109, B08405, doi:10.1029/2003JB002944, 2004; see also SOPAC Pole Rotation Tables for the latest and earlier monthly solutions of the CGPS model parameters.

Sella, G.F., T.H. Dixon, and A. Mao, REVEL: A model for recent plate velocities from space geodesy, J. Geophys. Res., 107, B4, doi:10.1029/2000JB000033, 2002.

Other plate motion calculators:

Lamont-Doherty Plate Velocity Calculator for NUVEL-1
(another variation for points near spreading ridges: Ridge Spreading Rate Calculator, also using NUVEL-1)

University of Tokyo Plate Motion Calculator for NUVEL-1, NUVEL-1A, and HS2-NUVEL1
(new version for NUVEL-1, NUVEL-1A, and HS3-NUVEL1A; another variation for points near spreading ridges: Seafloor Spreading Rate s Calculator, using NUVEL-1 or NUVEL-1A)

Utrecht University Plate Motion Calculator for NUVEL-1A or your own pole

Deutsche Geodätisches Forschungsinstitut Plate Motions calculator for NUVEL-1, NUVEL-1A, and APKIM2000 (Macromedia Flashplayer 6 plugin required)

Rice University Plate Motion Calculator for HS3-NUVEL1A

Last modified Friday, 08-Sep-2006 11:27:27 MDT

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