April 27, 2013
Tutorial - Earthquake Data Logger
about a year ago
Hello fellow Kiwi! I live in Wellington and had a similar idea recently after the earthquakes centered near Seddon which were strongly felt in Wellington too (see http://en.wikipedia.org/wiki/2013_Seddon_earthquake).
I connected a +/- 1.5g accelerometer to an old Arduino Mega I had lying around, blu-tacked it to our stone fireplace in the lounge and connected it (via USB) to a laptop for both power and so I could use a java program on the laptop as a data logger.
I was pretty chuffed with myself, was getting a sample rate of 366 per second for X, Y and Z co-ords. However, lots of noise in the readings meant it was hard to figure out if a real quake was happening (we get heaps of small quakes here, just like you guys do in ChCh (of course). Plus of course, as soon as I built it no major aftershocks came (for weeks…).
I was about to unplug but then a few days ago we had a Mag 5.1 which rumbled through near Seddon, which was strongly felt. I ran to the laptop (after checking the kids were OK…) and grabbed the data file. It was a beautiful trace of the quake passing through my house.
The best thing I found was that I could analyse a whole heap of things by correlating the data with the official GeoNet data. For example, by checking the timing difference between GeoNet and my accelerometer you can calculate the speed of the wave, calculate the peak acceleration, velocity and distance your house moved! Frequency of wave is also clearly determinable (try FFT command line on linux to get a fast fourier transform of the data).
I have some cool charts too, but can’t figure out how to upload them into the comment. If anyone is interested in me putting together a posting like the article above reply to this post and if I get enough interest I’ll make one.
However, just so you know it IS possible to get meaningful data about how your house is impacted in an earthquake from very low cost accelerometers and an arduino :)
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