Measuring Continental Drift with a Phone

Worldwide Continental Drift Velocities

Worldwide Continental Drift Velocities

Here in Colorado if you believe the above map (more detail), we’re moving a few centimeters a year west or south-west. Queue music, and a weekend project.

How is continental drift measured? It turns out there’s not a lot to it, you just superglue a GPS to a rock and take location measurements for a year or two. If you average out the noise of the GPS you should see it move over time.

I have an old Lumia phone that is worth about $5 on eBay yet will run Windows 10 so I grabbed Visual Studio 2015 and wrote a little app to grab the GPS location every second. The app also keeps the screen alive, displays the location and then sends the data off to a server. The “server” here is a Mac running a tiny little ruby daemon which listens for the GPS data and logs it to some files. There’s also a little plist file you put in your launchd directory to keep it running as a background service. A great excuse to learn how Windows 10 apps and ruby sockets work.

Now the “real” geologists, probably their GPS is bright orange, has solar power, a big drive to log data and special clamps to mount the whole thing to the bedrock that’s being measured. It probably has a wonderful view of the sky, and cost $20k or something. The concrete foundation of the house and superglue will have to suffice for mounting. We have interference from the (wooden) roof of the garage. The server might go down. The wifi will too, occasionally, and there is no buffering on the phone at this point so we’ll lose data here and there. The code is all available here.

I’m currently running the setup for a few days and will then superglue the phone to the foundation and forget about it for a few months while it collects data. Though there is one piece left to write for logging, we need to compress the files after they’ve been stagnant a while.

Analysis will come much later, and we’ll need a decent numerical library to make sure the averages are computed correctly. There are various other thing that can break like thermal expansion or some other effect may throw the whole thing off. Stay tuned!

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