Different ways to measure Plate Motion?

1. Oct 8, 2015

RJLiberator

1. The problem statement, all variables and given/known data

What's the difference in using GPS Data vs. using Magnetic anomalies, fracture zones, hot spots to analyze plate motion?

2. Relevant equations

3. The attempt at a solution

Seems like a question with a direct answer.
What's the difference between the two? I am struggling to find any notes or information on it. This is in reference to a report that went into detail about a GPS study of plate motions.
I need to know the difference between the two measuring tools to understand what's going on.

Any help?
Thank you.

2. Oct 8, 2015

Bystander

"GPS" stands for what?

3. Oct 8, 2015

RJLiberator

Global Positioning System

4. Oct 9, 2015

Bystander

How do you find your position with GPS?

5. Oct 9, 2015

RJLiberator

I'm not entirely sure, but do you use 3 different GPS satellites to find your position? "trilateration" and then using trilateration with distance = rate x time you can measure the location.

Am I on the right path there?

6. Oct 9, 2015

Staff: Mentor

Yes, with GPS system you can determine the position and detect motion (assuming it is fast enough and the accuracy of the position detection is good enough).

What about other methods? In what way do they prove the motion?

7. Oct 9, 2015

RJLiberator

This is purely a guess from my knowledge: But I would imagine in using fracture zones, magnetic anomalies, and hot spots, they use seismic data or relevant plate motion data to analyze it?

8. Oct 9, 2015

Bystander

Can you use the Hawaiian Islands to watch/indicate MOR (mid-ocean ridge) movement relative to Iceland?

9. Oct 9, 2015

RJLiberator

Hm..

I take it that your question is a hint towards a limitation.
I would think not unless you use GPS devices. Is this the limitation of the magnetic anomalies/fracture zones/hot spots that this question was alluding too?

10. Oct 9, 2015

Bystander

Or, a suggestion that GPS can be applied anywhere, whereas hotspots, fracture zones, magnetic anomalies, and other gross physical features of "plates" are limited in distribution.

11. Oct 9, 2015

RJLiberator

I see.
That makes sense.
Since GPS is long range, it can be applied anywhere over the earth.
While the fracture zones, magnetic anomalies, and hotspots are data that is driven by location.

12. Oct 9, 2015

Staff: Mentor

Also note: GPS gives pretty high accuracy and works here and now. What about other methods?

13. Oct 9, 2015

RJLiberator

I see. GPS gives high accuracy and near immediate results by definition of how the technology works.

The other method is dependent on massive field research, perhaps earth rumblings (seismic activity? or hot spot activity), and so is dependent on time.
Whereas, we can say "ok, load up the GPS data," we cannot say "ok, make the earth rumble."

Is that a way to understand it?

14. Oct 9, 2015

Staff: Mentor

Based on my limited knowledge of geology and geologic mapping, a common technique for analyzing plate motion is placing sensors on either side of the plate, and measuring (via GPS) their relative change in position.

Magnetic anomolies don't necessarily indicate plate motion, as far as I know. They can occur when there are large masses of some ferrous material beneath the surface. They can also occur in "stripes" on either side of a mid-ocean spreading site that is the junction of two plates. New ocean seafloor that is created at the spreading site extends out from the spreading site in two directions. The stripes of opposite polarity magnetism that appear on either side of the spreading zone are thought to occur due to the periodic switching of the earth's magnetic field, and can be used to give an idea of how fast the seafloor is moving on either side of the spreading zone.

Fracture zones (see https://en.wikipedia.org/wiki/Fracture_zone) result "from the action of offset mid-ocean ridge axis segments.are regions in the ocean where there are numerous faults." (Taken from the wiki article.) These fracture zones indicate motion of one plate relative to another.

Hot spots, such as the one currently below Hawaii island (the "big island") and others, such as the one that is believed to cause massive outpourings of lava in Washington state before moving east to produce the caldera at Yellowstone) provide evidence of plate motion. The hot spots are believed to be stationary on the earth's surface, while the plates slide across it. In the Hawaiian islands, the Pacific Plate is theorized as having moved NNW for a time, and then changing direction to about WNW (see https://en.wikipedia.org/wiki/Evolution_of_Hawaiian_volcanoes). The most recent volcanic action is off the coast of Hawaii, at Lo ihi sea mount. The oldest volcanoes in the chain are in the Emporor Sea Mounts, many of which are so eroded that they are no longer above sea level.

15. Oct 9, 2015

RJLiberator

Great information Mark, I'll be exploring some of your thoughts as we discuss this topic in my course this week.
Thanks.