Christchurch Quakes – Sonified

As you will have read, on Saturday the week before last, a large earthquake of 7.1 richter hit Christchurch and the aftershocks have continued ever since. Miraculously there was no loss of life, and it really is a miracle when you consider it was of similar scale to Haiti (7.0 and 230,000 people died) or Kobe, Japan (7.3 and 6,434 people died) – the saving factors seem to be the combination of strict building codes, time of the quake and the low density of people in the area… But for anyone living in New Zealand one of the strangest aspects of the event is how it was portrayed in foreign media – watch the first two minutes of this video and you’ll see what I mean:

Back in reality Christchurch is slowly assessing the damage, but still the aftershocks continue. To get some idea of the number of aftershocks this timelapse map of quakes is worth a look, but as soon as I saw it I knew I wanted to hear it – not to hear a version of the earthquake, but to get an idea for the pattern & rhythm of the aftershocks… But how to achieve it? First I went to Geonet who provide a constant stream of data on earthquakes throughout New Zealand, and via the search function I could download a CSV document of all the earthquakes in the Christchurch region from the first one, for the following week. But how to turn that data into sound?

First I looked at the timescale: 7 days = 168 hours, so I realsied if I made one hour equal one second, then a week would be approximately 2 minutes long, which is a listenable duration. This might get a bit techy/boring but I decided to use MIDI notes, so that I could trigger whatever sound I like and as I use ProTools I thought there must be a way to create scripted MIDI notes based on the time data. Now I didn’t want to be converting time into timecode or bars & beats so I resorted to a timescale that kept the maths easy: samples. Working at 48k ie 48000 samples per second meant I could use a spreadsheet to convert the real time timescale (hours and minutes) first to my new timescale (1hour = 1 second) and then into samples. So I ended up with a spreadsheet with a vertical stream of data where the first quake hit at time=00000 and consecutive quakes followed:

Quake timeline

Next I wrote a Quickeys script to copy the timeline sample number from Excel, switch to ProTools and spot a new MIDI note to that sample number. So five minutes later I had a MIDI sequence of the earthquakes, scaled to my new timeline. The next step was wrangling the richter scale data to alter the velocity of each MIDI note, so I first calculated the maximum quake value to be full velocity ie 127, and then scaled all the aftershocks relatively, ending up with a stream of MIDI velocity values as below:

Quake velocities

Next I wrote a second Quickeys script to copy the velocity data out of Excel, switch to ProTools, skip to the next MIDI note and alter the velocity using my scaled data. Once I had that done I then went looking for sounds that were velocity sensitive in interesting ways, so I could actually hear what all this data crunching sounded like…

First choice was a Koto patch in Absynth 5:

Second choice was a Squarewave sub bass patch, also in Absynth

Kind of interesting huh? If you own a subwoofer, try sitting on it while you play the Squarewave bass version, and then imagine thats a week in your shattered life, not 2 minutes but 7 days!

Relatedly today I had a couple of interesting conversations with friends who have had visitors from Christchurch staying, people who dearly needed a break from the turmoil, and both people commented about how hyper sensitive to low frequencies their visitors were. One example was from sitting on a deck here in Wellington, and like all decks there is some resonance when someone walks across it, but their visitors literally jumped when anyone unexpectedly moved, such was the state of their nerves. And similarly someone in Dunedin described their visitors freaking out at the low frequencies of trucks going by on the motorway.

It is an interesting reflection on what we ignore through familiarity, I always smile when I hear someone complain about a car going by with the hell sound system, booming out beats & basslines, and yet the same people don’t seem to even notice the similar scale of low frequencies a passing bus or truck is firing at them. Don’t believe me? Have a listen to these two recordings, the first was recorded in a cafe in Wellington (the old Bodega cafe) as a bus goes past, the second is traffic in Barcelona during rush hour. Each plays normally, i.e. as heard, & then with all the high frequencies removed. NOTE: if you’re from Christchurch you might want to skip this part – my thoughts are with you, quiet peaceful thoughts with no low frequencies…

PS if you want to try messing with the MIDI file, here it is for download – comment me a link if you make anything interesting with it!

PPS I’m no scientist or mathematician, nor am I a programmer so I wouldn’t go basing any thesis on my dodgy scripting, but it is interesting to appreciate the relentless pounding Christchurch is taking…. If you need visual evidence have a look here

4 thoughts on “Christchurch Quakes – Sonified

    1. jase

      Hi Tim,
      Thanks for the earthquake rendition. I’m in Christchurch and lived through the quake. This is particularly interesting for me as the eartyhquake and subsequent aftershocks have all been very much audio experiences, ie. I tend to hear the event before feeling it, much like our two cats. I’m interested to know what software you used to do the scripting. Sorry, I have no experience with such, but I’m keen to learn.

      I also agree with your observation of low frequency sounds out and about.

      Ps. did you know that COCA, are exhibiting an earthquake show here (free to all) in Chch at the moment, I’m sure they’d be very interested in your MIDIfied take.


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