How-quickly-are-we-moving -only-2014may

Version: May 2014

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How quickly are we moving?

A quick guide to finding EarthScope Plate Boundary Observatory GPS

station(s) near you

education@unavco.org

Quick look: On the maps below, find the closest GPS velocity vector arrow to

your school, park, or favorite location.

• Each vector arrow shows the velocity of a single GPS station installed permanently to

the ground. If the Earth moves, the GPS stations record this movement.

• The GPS vector’s tail is the starting location of the GPS monument.

• The direction the vector points is the direction the GPS station is moving.

• The length of the vector shows how fast the GPS station is moving.

• Keep in mind that there might be faults, such as the San Andreas fault, between your

school and nearby GPS stations.

Explore further using the GPS Velocity Viewer use a Google Search for UNAVCO Velocity

Viewer.

Version: May 2014

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Note: Every tectonic plate on Earth

is in motion. Scientists compare the

motion of one tectonic plate or

region relative to another tectonic

plate to view the differences in

motion. The maps on the first two

pages use the North American

Reference Frame where the interior

of the North American plate is stable,

e.g. not moving.

Version: May 2014

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Reference frame: no net rotation

I. Five easy steps to make a world map showing the divergent motion in

the mid-Atlantic:

• Go to the GPS Velocity Viewer, to explore the GPS velocity vectors – use a Google

Search for UNAVCO Velocity Viewer. The viewer starts with a zoom on the western

United States and shows the overall velocities measured at each GPS station in the

PBO network

1. Zoom out on the map (there’s a quirk with the international date line – sometimes the

vectors do not display… in Beta testing.)

2. Under Data Source, choose no net rotation.

3. Under vector color, choose yellow.

4. Under Sites displayed, select show one in ten.

5. Click on “Draw map”.

II. To explore the plate motion by viewing the GPS velocity

vectors near a favorite place:

1. Change the Data Source to UNAVCO GPS velocities, NAM08 to change into the North

America Reference Frame.

2. Change Sites displayed, select show one in ten to help the map display more quickly.

3. Zoom in to a favorite area (for example, the state or region of interest.) If you don’t see any

vectors, zoom out.

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4. Display more vectors using Sites displayed, such as show one in five.

5. Are the vectors very short?

• In the mid-continent, the North American plate is not moving much in the North America

Reference Frame - try changing the Data Source UNAVCO GPS velocities igs05.

• The scale can be changed by selecting choices under Velocity display scale.

6. Learn more about one GPS station:

a. Click the checkbox button for Station

labels to see more information for each

GPS station.

b. Click the green bubble of a station.

The information box displays:

! The GPS station 4-character id.

! Horizontal speed - indicates how quickly

the ground and that GPS station is moving.

! The direction of motion in degrees from

North.

! GPS time series plot with a link to a

large printable plot (for UNAVCO GPS

stations).

! A link to download the data into a spreadsheet program (for UNAVCO GPS stations).

7. Further customize your map by using the controls at the side of the map.

! The GPS Data Source – look at the velocity vectors keeping a tectonic plate fixed as

the reference frame

o UNAVCO GPS velocities Nam08 uses a North American Reference Frame –

there are more than 1460 GPS stations primarily from the United States.

o UNAVCO GPS velocities igs05 uses IGS reference frame.

o Tectonic plate based reference frames use more than 5000 stations around

the world. Shows the velocities compared to keeping that tectonic plate fixed

(not moving).

! Change the Velocity display scale and Velocity vector color.

! Show error ellipses – this shows the relative accuracy of the GPS data.

! View the tectonic plate boundaries, recent earthquakes, and locations of volcanoes by

turning their symbols on and off.

8. To learn more about graphing this data, see a step-by-step tutorial:

http://serc.carleton.edu/eet/platemotion/all_parts.html

9. Now that you have explored the plate motion for one location, roam the world and discover

what you can find! Where can you find where plates collide, split apart, and slide past each

other? How about the plate boundaries – where are they narrow? Where are they wide

boundary zones?