You can superimpose observed and/or model velocity vectors on your map, showing the direction and rate of plate movement. The velocity vectors represent a compilation of 2933 geodetic measurements from around the world. A remarkable characteristic of the geodetic compilation is that you can select from 7 frames of reference, allowing a visual representation of both 'absolute' plate motion (in a no-net rotation reference frame) and relative motion along all of the world's plate boundaries.
First, select a plate in relation to which the velocities will be drawn. For example, if you choose Caribbean, the velocities will be drawn in relation to the fixed Caribbean plate. Then, select the type of data to be displayed. (In browsers other than Netscape 4, the options will not display until you have selected a plate). You can select from the following:
Model (A surface velocity model based on GPS measurements, geologic fault
slip rates, and earthquake focal mechanisms)
Observational data (A compilation of observed surface velocities based on GPS measurements)
Both (Displays model and observational data)
To change plates, select another item in the drop-down box. To turn them off altogether, click on No Plate Velocities. To switch between model, observational, or both types of data, click on the appropriate radio button. Note that the velocities will not display until you have clicked on the Make Changes button. In addition, the velocities will appear on all subsequent maps until you deselect them.
 |
 |
The map shows the location of the plates from which you can choose. Each plate is described briefly below. For more information, access the USGS Major Tectonic Plates of the World and Information on Plate Tectonics websites, the NASA Digital Tectonic Activity Map of the Earth website, or the This Dynamic Planet PDF file. Below the table is a map from which the velocities and strain were derived.
|
Plate Reference Frames
|
Plate Descriptions
|
|
No Plate Velocities
|
Turns off all velocities |
|
North American
|
North American continent plus the western North Atlantic Ocean |
|
Pacific
|
Pacific Ocean west of the East Pacific Rise and east of the Mariana trench |
|
Eurasian
|
Eurasian continent north of the Alpine-Himalayan mountain belt and west of the Baikal Rift |
|
Caribbean
|
Caribbean Sea |
|
Cocos
|
East central Pacific Ocean (northeast of the Galapagos Islands) |
|
Nazca
|
Southeastern Pacific Ocean (southeast of the Galapagos Islands) |
|
South American
|
South American continent plus southwestern Atlantic Ocean |
|
No-Net-Rotation
|
Reference frame describing the "average" velocity for the global system of tectonic plates |
The velocities and strain are derived from the plate tectonic model of Kreemer et. al. 2002 shown below. Black areas are defined as rigid plates; tan areas are deformable boundary zones between the plates.
To close this window, click on the X at the end of the menu bar or in the upper right corner of the window.
