UC Berkeley’s Seismic Carillon

I’ve had a soft spot for carillon bells ever since my choir camp cohort got a behind-the-scenes tour at the National Cathedral’s awesome bell-tower in Washington D.C. As a joint music and geology nerd, I had never seen a phenomenon that so perfectly combined my interests until this popped up on NPR – a set of carillon bells hooked up to a seismograph in the Hayward Fault that runs near UC Berkeley.

For three spans of ten minutes on February 3, a geologically-inspired symphony of sound and light entertained visitors to the lawn Outside Sather Tower, which was celebrating its 100th anniversary. The project was conceived by Berkeley professors Edmund Campion (composer), Ken Goldberg (artist and roboticist), and Greg Niemeyer (artist), who were intrigued my the idea of a new model of data visualization.

It’s a fun thought – that the unimaginable stockpiles of data collected by modern society is being put to such a whimsical, productive use.

I found that the news coverage missed something –  how the seismic data was transposed into a range audible to humans, and any nice geology info on the fault itself.

Faults and Plate motion

The fault highlighted in yellow is the section of the Hayward that slipped in the large 1868 earthquake.

Thankfully, the USGS is there to cover my late-night geologic information needs. They have an accessible and well-laid out series of pamphlets and infographics on the fault, my favorites of which can be found here. Unlike its more famous cousin the San Andreas fault, which is “locked” and only moves (In the Bay area) during major earthquakes, the Hayward fault moves along at a constant 5mm-per-year creep in between its major earthquakes, providing gentle tremors to be transposed for carillon at any given time. Statisticians are wary of the fault, which has a historical trend of producing a large quake every 140 years; the East Bay is “overdue” for a quake as of 2008.

hayward fault and belltower

Relationship between the Hayward Fault and Sather Campanile (Bell-tower) – click through for better resolution. “Up” is east; north is to the left.

Unfortunately, the how and why of earthquake tremor musicality will have to be a subject for another day, when I have the time to dig through archives and faculty pages for tidbits. To be updated!

Update: Well, that escalated quickly. Research into the exact interface between the fault and the music ended up careening through sound systems and acoustic technologies, crashed through my intermediate understanding of calculus, and soared right over my head. I knew I was lost when I found myself staring blankly at the Wikipedia page of Fourier Analysis. While I always love exploring new subjects, sometimes I just have to pick my battles. I changed tactics: instead of approaching the problem through the musical side, I turned to looking up the actual seismic patterns.

The earth’s periodic shrugs and scrapings all produce two kinds of displacement. The faster “P” compression wave moves through the ground like a slinky that’s jostled while held straight – the same manner as sound traveling through air. A moment later, the slower “S” transverse wave moves like a flicked jump-rope.Those waves show up on a seismograph as an oscillation – almost like a sine function, if you squint. I’m guessing that the Carillon’s program took those seismic oscillations and gave them the characteristics of sound waves.

The first thing that came to mind when connecting sounds with oscillations is the Sound Track segment from my childhood favorite, the 1940’s Disney Fantasia. It gives a fun introduction to the connection between a wave’s amplitude and sound’s volume, and the relationship between the frequency and the pitch.

Finding data on the Hayward Fault’s movements is easy – it has that magical combination of a high-risk setting and nearby higher education that lead to it being one of the most-studying faults in the USA. The Berkeley Digital Seismic Network includes 30 data-collection stations, including this one right below the bell-tower. The North California Earthquake Data Center has a great “create a seismogram” app (here) that allowed me to access data from that collection station for the duration of one of the performances. USC Berkeley Seismic OscillationsOh the joys of the internet, that I can just google this!

This seismogram shows a wave varying in frequency and amplitude. If this were a sound wave, it would sound something like a mild, atonal siren sliding from pitch to pitch and varying in loudness. USC composer/professor Edward Campion and Jeff Lubow at the Center for New Music and Audio Technologies managed to turn this continuous oscillation into a discontinuous series of bell tones, which might as well be magic to a someone like me who knows nothing about sound engineering. However they did it, they created a wonderful performance!

In the theme of accessible data visualization, maybe they could find a way to turn some other dramatic earthquake events in the seismogram archives into musical compositions? I would totally buy a CD.

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