Erratic Furnaces of Infrasound: Volcano Acoustics
Welcome back to Hearing the UnHeard, Sounding Out‘s series on how the unheard world affects us, which started out with my post on hearing large and small, continued with a piece by China Blue on the sounds of catastrophic impacts, and now continues with the deep sounds of the Earth itself by Earth Scientist Milton Garcés.
Faculty member at the University of Hawaii at Manoa and founder of the Earth Infrasound Laboratory in Kona, Hawaii, Milton Garces is an explorer of the infrasonic, sounds so low that they circumvent our ears but can be felt resonating through our bodies as they do through the Earth. Using global networks of specialized detectors, he explores the deepest sounds of our world from the depths of volcanic eruptions to the powerful forces driving tsunamis, to the trails left by meteors through our upper atmosphere. And while the raw power behind such events is overwhelming to those caught in them, his recordings let us appreciate the sense of awe felt by those who dare to immerse themselves.
In this installment of Hearing the UnHeard, Garcés takes us on an acoustic exploration of volcanoes, transforming what would seem a vision of the margins of hell to a near-poetic immersion within our planet.
– Guest Editor Seth Horowitz
The sun rose over the desolate lava landscape, a study of red on black. The night had been rich in aural diversity: pops, jetting, small earthquakes, all intimately felt as we camped just a mile away from the Pu’u O’o crater complex and lava tube system of Hawaii’s Kilauea Volcano.
The sound records and infrared images captured over the night revealed a new feature downslope of the main crater. We donned our gas masks, climbed the mountain, and confirmed that indeed a new small vent had grown atop the lava tube, and was radiating throbbing bass sounds. We named our acoustic discovery the Uber vent. But, as most things volcanic, our find was transitory – the vent was eventually molten and recycled into the continuously changing landscape, as ephemeral as the sound that led us there in the first place.
Volcanoes are exceedingly expressive mountains. When quiescent they are pretty and fertile, often coyly cloud-shrouded, sometimes snowcapped. When stirring, they glow, swell and tremble, strongly-scented, exciting, unnerving. And in their full fury, they are a menacing incandescent spectacle. Excess gas pressure in the magma drives all eruptive activity, but that activity varies. Kilauea volcano in Hawaii has primordial, fluid magmas that degass well, so violent explosive activity is not as prominent as in volcanoes that have more evolved, viscous material.
Well-degassed volcanoes pave their slopes with fresh lava, but they seldom kill in violence. In contrast, the more explosive volcanoes demolish everything around them, including themselves; seppuku by fire. Such massive, disruptive eruptions often produce atmospheric sounds known as infrasounds, an extreme basso profondo that can propagate for thousands of kilometers. Infrasounds are usually inaudible, as they reside below the 20 Hz threshold of human hearing and tonality. However, when intense enough, we can perceive infrasound as beats or sensations.
Like a large door slamming, the concussion of a volcanic explosion can be startling and terrifying. It immediately compels us to pay attention, and it’s not something one gets used to. The roaring is also disconcerting, especially if one thinks of a volcano as an erratic furnace with homicidal tendencies. But occasionally, amidst the chaos and cacophony, repeatable sound patterns emerge, suggestive of a modicum of order within the complex volcanic system. These reproducible, recognizable patterns permit the identification of early warning signals, and keep us listening.
Each of us now have technology within close reach to capture and distribute Nature’s silent warning signals, be they from volcanoes, tsunamis, meteors, or rogue nations testing nukes. Infrasounds, long hidden under the myth of silence, will be everywhere revealed.
I first heard these volcanic sounds in the rain forests of Costa Rica. As a graduate student, I was drawn to Arenal Volcano by its infamous reputation as one of the most reliably explosive volcanoes in the Americas. Arenal was cloud-covered and invisible, but its roar was audible and palpable. Here is a tremor (a sustained oscillation of the ground and atmosphere) recorded at Arenal Volcano in Costa Rica with a 1 Hz fundamental and its overtones:
In that first visit to Arenal, I tried to reconstruct in my minds’ eye what was going on at the vent from the diverse sounds emitted behind the cloud curtain. I thought I could blindly recognize rockfalls, blasts, pulsations, and ground vibrations, until the day the curtain lifted and I could confirm my aural reconstruction closely matched the visual scene. I had imagined a flashing arc from the shock wave as it compressed the steam plume, and by patient and careful observation I could see it, a rapid shimmer slashing through the vapor. The sound of rockfalls matched large glowing boulders bouncing down the volcano’s slope. But there were also some surprises. Some visible eruptions were slow, so I could not hear them above the ambient noise. By comparing my notes to the infrasound records I realized these eruption had left their deep acoustic mark, hidden in plain sight just below aural silence.
I then realized one could chronicle an eruption through its sounds, and recognize different types of activity that could be used for early warning of hazardous eruptions even under poor visibility. At the time, I had only thought of the impact and potential hazard mitigation value to nearby communities. This was in 1992, when there were only a handful of people on Earth who knew or cared about infrasound technology. With the cessation of atmospheric nuclear tests in 1980 and the promise of constant vigilance by satellites, infrasound was deemed redundant and had faded to near obscurity over two decades. Since there was little interest, we had scarce funding, and were easily ignored. The rest of the volcano community considered us a bit eccentric and off the main research streams, but patiently tolerated us. However, discussions with my few colleagues in the US, Italy, France, and Japan were open, spirited, and full of potential. Although we didn’t know it at the time, we were about to live through Gandhi’s quote: “First they ignore you, then they laugh at you, then they fight you, then you win.”
Fast forward 22 years. A computer revolution took place in the mid-90’s. The global infrasound network of the International Monitoring System (IMS) began construction before the turn of the millennium, in its full 24-bit broadband digital glory. Designed by the United Nations’s Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), the IMS infrasound detects minute pressure variations produced by clandestine nuclear tests at standoff distances of thousands of kilometers. This new, ultra-sensitive global sensor network and its cyberinfrastructure triggered an Infrasound Renaissance and opened new opportunities in the study and operational use of volcano infrasound.
Suddenly endowed with super sensitive high-resolution systems, fast computing, fresh capital, and the glorious purpose of global monitoring for hazardous explosive events, our community rapidly grew and reconstructed fundamental paradigms early in the century. The mid-naughts brought regional acoustic monitoring networks in the US, Europe, Southeast Asia, and South America, and helped validate infrasound as a robust monitoring technology for natural and man-made hazards. By 2010, infrasound was part of the accepted volcano monitoring toolkit. Today, large portions of the IMS infrasound network data, once exclusive, are publicly available (see links at the bottom), and the international infrasound community has grown to the hundreds, with rapid evolution as new generations of scientists joins in.
In order to capture infrasound, a microphone with a low frequency response or a barometer with a high frequency response are needed. The sensor data then needs to be digitized for subsequent analysis. In the pre-millenium era, you’d drop a few thousand dollars to get a single, basic data acquisition system. But, in the very near future, there’ll be an app for that. Once the sound is sampled, it looks much like your typical sound track, except you can’t hear it. A single sensor record is of limited use because it does not have enough information to unambiguously determine the arrival direction of a signal. So we use arrays and networks of sensors, using the time of flight of sound from one sensor to another to recognize the direction and speed of arrival of a signal. Once we associate a signal type to an event, we can start characterizing its signature.
Consider Kilauea Volcano. Although we think of it as one volcano, it actually consists of various crater complexes with a number of sounds. Here is the sound of a collapsing structure
As you might imagine, it is very hard to classify volcanic sounds. They are diverse, and often superposed on other competing sounds (often from wind or the ocean). As with human voices, each vent, volcano, and eruption type can have its own signature. Identifying transportable scaling relationships as well as constructing a clear notation and taxonomy for event identification and characterization remains one of the field’s greatest challenges. A 15-year collection of volcanic signals can be perused here, but here are a few selected examples to illustrate the problem.
First, the only complete acoustic record of the birth of Halemaumau’s vent at Kilauea, 19 March 2008:
Here is a bench collapse of lava near the shoreline, which usually leads to explosions as hot lava comes in contact with the ocean:
Here is one of my favorites, from Tungurahua Volcano, Ecuador, recorded by an array near the town of Riobamba 40 km away. Although not as violent as the eruptive activity that followed it later that year, this sped-up record shows the high degree of variability of eruption sounds:
The infrasound community has had an easier time when it comes to the biggest and meanest eruptions, the kind that can inject ash to cruising altitudes and bring down aircraft. Our Acoustic Surveillance for Hazardous Studies (ASHE) in Ecuador identified the acoustic signature of these type of eruptions. Here is one from Tungurahua:
Our data center crew was at work when such a signal scrolled through the monitoring screens, arriving first at Riobamba, then at our station near the Colombian border. It was large in amplitude and just kept on going, with super heavy bass – and very recognizable. Such signals resemble jet noise — if a jet was designed by giants with stone tools. These sustained hazardous eruptions radiate infrasound below 0.02 Hz (50 second periods), so deep in pitch that they can propagate for thousands of kilometers to permit robust acoustic detection and early warning of hazardous eruptions.
In collaborations with our colleagues at the Earth Observatory of Singapore (EOS) and the Republic of Palau, infrasound scientists will be turning our attention to early detection of hazardous volcanic eruptions in Southeast Asia. One of the primary obstacles to technology evolution in infrasound has been the exorbitant cost of infrasound sensors and data acquisition systems, sometimes compounded by export restrictions. However, as everyday objects are increasingly vested with sentience under the Internet of Things, this technological barrier is rapidly collapsing. Instead, the questions of the decade are how to receive, organize, and distribute the wealth of information under our perception of sound so as to construct a better informed and safer world.
http://www.iris.edu/bud_stuff/dmc/bud_monitor.ALL.html, search for IM and UH networks, infrasound channel name BDF
Milton Garcés is an Earth Scientist at the University of Hawaii at Manoa and the founder of the Infrasound Laboratory in Kona. He explores deep atmospheric sounds, or infrasounds, which are inaudible but may be palpable. Milton taps into a global sensor network that captures signals from intense volcanic eruptions, meteors, and tsunamis. His studies underscore our global connectedness and enhance our situational awareness of Earth’s dynamics. You are invited to follow him on Twitter @iSoundHunter for updates on things Infrasonic and to get the latest news on the Infrasound App.
Featured image: surface flows as seen by thermal cameras at Pu’u O’o crater, June 27th, 2014. Image: USGS
REWIND! If you liked this post, check out …
SO! Amplifies: Ian Rawes and the London Sound Survey — Ian Rawes
Sounding Out Podcast #14: Interview with Meme Librarian Amanda Brennan — Aaron Trammell
Catastrophic Listening — China Blue
Calling Out To (Anti)Liveness: Recording and the Question of Presence
Editor’s Note: Even though this is officially Osvaldo Oyola‘s final post as an SO! regular–his brilliant dissertation on Latino/a identity and collection cultures is calling–I refuse to say goodbye, perpetually leaving the door open for future encores. He has been a bold and steadfast contributor–peep his extensive back catalogue here–and we cannot thank him enough for bringing such a whipsmart presence to Sounding Out! over the years. Best of luck, OOO, our lighters are up for you!–J. Stoever-Ackerman, Editor-in-Chief
As several of my previous Sounding Out! Blog posts reveal, I am intrigued by the way popular music seeks to establish its authenticity to the listener. It seems that recorded popular music seeks out ways to overcome its lack of presence as compared to a live performance, where a unified and spontaneous sense of immediacy seems to automatically bestow the aura of the “authentic”—a uniqueness that, ironically, live reproducibility engenders. Throughout my time as a Sounding Out! regular, I have explored how authenticity may be conferred through artists affecting an accent as a form of musical style, comparing their songs to other “less authentic” forms of music through a call to nostalgia, or even by highlighting artificiality through use of auto-tune.
One of the ways that artists and producers get past a potential lack of authenticity when recording is through call outs to “liveness.” I am not referring to concert recordings (though there are ways that they can be used), but elements like counting off at the beginning of songs or introducing some change or movement in a song. There is no practical need to count off “One, two, three, four!” at the beginning of a recording of a song if it is being pieced together through multiple tracks and overdubs. These days a “click track” or adjustment post-recording can keep all the players in time even if not necessarily playing at once; even if a song is being recorded as a kind of studio jam, the count off could be edited out. It is an artifact of the creation, not a sign of creation itself. Instead, the counting can become an accepted and notable part of the song, like Sam the Sham and the Phaorahs performing “Wooly Bully,” giving it an orientation to time—the sense that all these musicians were present together and playing their instruments at once and needed this unique introduction to keep them all in tempo.
Similarly, sometimes artists call out to other musicians, giving instructions when no instructions are needed, assuming that most popular music is recorded in multiple takes using multiple tracks. In Parade‘s “Mountains,” Prince commands the Revolution, “guitars and drums on the one!” when clearly they had rehearsed when putting together the song, and ostensibly knew when the drum and guitar breakdown was coming up. Prince, furthermore, joins artists as varied as the Grateful Dead and the Beastie Boys in mixing concert recordings with studio overdubs to capture a “live” sound on songs like “It’s Gonna Be a Beautiful Night” and “Alligator.” Even something as ubiquitous as guitar feedback is a transformation of an artifact of live performance into a sound available for use in recording—something that was purposefully avoided until John Lennon’s happy accident when in the studio to cut “I Feel Fine.” Until then, playing with feedback was a way to demonstrate performance skills through onstage vamping.
These varied calls to liveness provide a sense of authenticity to music made via the recording studio, denoting what I understand as the spontaneous sociability of music. Count-offs and studio shout-outs provide a sense of unified presence to a performance, especially if the performance has actually been constructed piecemeal and over time. This is something of a remnant of an old-fashioned notion that recorded music is measured in quality in comparison to live performance. It’s any idea that hung around both implicitly and explicitly long after bands started experimenting in the studio with effects that ranged from the difficult to the impossible to replicate on stage, and reinforced through recordings by performers who purposefully referenced their lauded live performances.
For example, James Brown’s “Get Up (I Feel Like Being a) Sex Machine” is built on this conceit. The entire song is a conversation, a call and response between James Brown and his band, the J.B.’s. From the opening line, Brown introduces the song as moment in time in which he is compelled to do his thing, but he demands both encouragement and cooperation from the band in order to achieve it. When Brown asks Bobby Byrd, “Bobby! Should I take ’em to the bridge?” we as listeners are invited to play along with the idea that it has suddenly came into his head to have the band play the bridge—as it might’ve happened (and thus been practiced) countless times in his legendary live shows. It suggests a form of spontaneity that the reality of recording would otherwise drain from the song. Sure, according to RJ Smith’s The One: The Life and Music of James Brown (2012), “Get Up” was recorded in only two takes–already fairly amazing–but the very nature of the song makes it sound like it was recorded in one, even if it had to be broken up into two sides of a 7-inch. That reality doesn’t matter—what matters when listening is the feeling that we, as listeners, are being allowed to partake in the capturing of what seems like one unique, and continuous, moment.
The question then arises: What about recorded music that does the opposite, that makes a point of highlighting its artificial construct—the impossibility of its spontaneous performance? While there are examples that date back at least to the 1960s, does this shift highlight a difference in aesthetic concerns by the pop music audience? If calls to “liveness” suggest a spontaneous sociability to music, what do the meta references to their songcraft suggest about what is important to music now?
The classic example is Ringo Starr’s bellow, “I GOT BLISTERS ON MY FINGERS!” at the end of the Beatles’ “Helter Skelter,” an exclamation made after umpteen takes of the song recorded on the same day, but there are more contemporary and even more obvious examples. Near the end of Outkast’s “Prototype,” (at 4:21) Andre 3000 can be heard talking to his sound engineer John Frye about the ad libs, “Hey, hey John! Are we recording our ad libs? Really? Were we recording just then? Let me hear that, that first one. . .” There is an interesting tension here between the spontaneity of an “ad lib” and listening back to pick the best one or further develop one when re-recording, and Andre in his role as producer decided to keep it in as part of the final product. The recording itself becomes part of the subject of the song as a kind of coda. The banter is actually a brilliant parallel to the content of the song, which undermines the typical “we’ll be together forever” love song trope for one that highlights the reality of serial monogamy common in American culture and lessons each relationship potentially provides us for the next. Rather than pretend that a romantic relationship is a unique and eternal thing, the song admits the work and changes involved, just as it admits that the seemingly special spontaneity of a song is developed through a process.
Of course, hip hop as a genre, with its frequent use of sampling, tends to make its recording process very evident. While it is possible to play samples “live” using a digital sampler or isolating sections on vinyl via the DJ as band member, the use of pre-recorded fragments means that rap music relies on the vocal dynamics of rap to carry the sense of spontaneity. Yet, in 1993’s “Higher Level,” KRS-One opens with a description of the time and place of the recording—“5 o’clock in the morning” at “D&D Studios,” establishing forever when and where and thus how the recording is happening. Five o’clock in the morning places the creation of the song with a context of working and rocking all through the night to get the album completed. The song may or may not have actually been recorded last, but its placement at the end of Return of the Boom Bap, gives it a sense of a last ditch effort to complete the collection of songs. The fact that “5 o’clock in the morning” is likely also among the cheapest available studio times potentially highlights budgetary concerns in the recording itself. This is a rare thing to include in recording, though the Brand New Heavies cap off the dissolution of their 1994 track “Fake” into pseudo-jazz-messing-around with one their members chiding, “a thousand dollar a day studio!” This is a different kind of call to authenticity, as a budgetary concern is an implicit to a “realness” defined by being non-commercial.
One of my all-time favorite examples is a few years older than “Higher Level”—“Nervous” by Boogie Down Production: “written, produced and directed by Blastmaster KRS-One,” which includes an attempt to explain how a song is put together on the “48-track board.” Instead of calling instructions to a band, KRS points out that DJ Doc is doing the mixing and instructs him to “break it down, Doc!” just before a beat breakdown (listen at around 1:40). He explains, “Now, here’s what we do on the 48-track board / We look around for the best possible break / And once we find it, we just BREAK,” and then the pre-recorded beat seems to obey his command, breaking down to just the bass drum and a sampled electric piano from Rhythm Heritage’s “The Sky’s the Limit.” Later, he says, “We find track seven, and break it down!” and the music shifts to just the bass guitar and some tinny synth high-hats.
So how does highlighting the recording circumstances, or just bringing attention to the fact that the song being listened to is a multiple-step process of recording and post-production benefit the song itself? Is it like I mentioned in my 2011 “Defense of Auto-Tune” post, that this kind of attention re-establishes authenticity by making its constructed nature transparent? I’d say yes, in part, but I also think that–through its violation of the expectation of seamlessness–the stray track or reference to recording within a song is a nod to a different kind of skillfulness. Exhortations such as “Take it to the Bridge” give an ironic nod to the extemporaneous to call attention to the diligent workmanship and dedication demanded by studio songcraft. Traditionally, live audiences may appreciate a flawless or nearly flawless performance and understand a masterful recovery from (and/or incorporation of) error as the signs of a good show, but, these moments that call attention to the recording studio situation claim there something to appreciate in the fact that Ringo Starr endured 18 takes of “Helter Skelter” until he had painful blisters, or that KRS-One and DJ Doc worked out the proper way to “feel around” the mixing board to make a grooving collage of sounds as disparate as the theme from “Rat Patrol” and WAR’s “Galaxy.”
KRS may have once admonished other MCs to “make sure live you is a dope rhyme-sayer,” but clearly he believes liveness—whether implicitly or explicitly—is not the only measure of musical ability. Rather, the highlighting of labor in the construction of a recording becomes its own kind of (anti-)vamping and demonstration of skill, and of a different kind of sociability in making music that these conversational snippets and references to other people in the studio make clear. This kind of attention to the group labor is especially important as various recording technologies become increasingly available to the wider public and allow for an isolated pursuit of recording music. Just as calls to liveness in recording engage the listener in ways that suggest participation as a live audience, calls to anti-liveness also engage the listener, but by bringing them across time and space into the studio to witness to a different form of great performance.
Osvaldo Oyola is a regular contributor to Sounding Out! and a PhD Candidate in English at Binghamton University working on his dissertation, “Collecting Identity: Popular Culture and Narratives of Afro-Latin Self in Transnational America.” He also regularly posts brief(ish) thoughts on music and comics on his blog, The Middle Spaces.
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Evoking the Object: Physicality in the Digital Age of Music–-Primus Luta
Experiments in Agent-based Sonic Composition–Andreas Pape
Musical Objects, Variability and Live Electronic Performance—Primus Luta