Field Recordings - Earth

This project is an investigation into the lower realms of electromagnetic signal. Rather than listening to the saturated signals from above, this project turns attention to the depths below.

The initial idea was sparked by an article by geophysicists Louis Lanzerotti and Giovanni Gregori. This paper considers the intriguing interaction between the wires and pipes of human infrastructure and telluric currents. Though considered a relatively obscure field of research these days, there has been over 150 years worth of studies into these natural voltage fluctuations observed below the surface of the earth. In tracing a brief history, the writers speculate that earlier studies of telluric currents yielded inaccurate data due to improper measurement practices. For example, a researcher compromises the study by grounding the wire used to measure earth currents to water pipes. Using underground pipes as an electrical ground is common practice, though for this purpose, instead of observing a contained area the ground connection increased the impedance to the length of the entire pipe system, essentially creating a massive underground antenna network (it's is also worth noting this researcher's wonderful surname):

"The first 75 to 100 years of Earth current work produced considerable debate as to causes and disagreements among researchers as to the magnitude of the effect at given times. Gish noted that better agreement between independent measurements often occurred when relatively long lengths of wire were used. Today it is clear that such a situation could easily arise from experimental procedures such as improper grounding of a wire and an insufficiently high impedance in the measuring system. For example in the work of Airy (1868) the wires were grounded to water pipes, which themselves obviously could carry currents flowing in the entire region over which the relatively short lengths of wire extended. In this case, the pipe network was the receiving antenna, even more than the lengths of wire.”

Lanzerotti, Louis, and Giovanni Gregori. "Telluric Currents: The Natural Environment and Interactions with Man-Made Systems." Chap. 16 In The Earth's Electrical Environment, edited by Geophysics Study Committee National Research Council. 232-57. Washington D.C.: National Academy Press, 1986.

Through this I became intrigued by the idea that metallic subterranean infrastructure may be unwittingly tuned into signals from above and below the surface of the earth. Voltage fluctuations are channeled to, and already present in the great mass below our feet, so on both a conceptual and technical level I wanted to turn the antenna around.

Process

As an experiment, I proceeded to see if I could simply reverse the process of my VLF Sky recordings by replacing the connection to the skyward whip antenna with buried metallic pipes. Of course this still required an additional earth, which I imagined could be treated in one of several ways: it could remain unattached; it could be earthed several meters away from the antenna point; or attached to exposed infrastructure such as nearby metal fences. While undertaking my test recordings, I tried variations of these ideas.

So far several urban recordings have been made and unsurprisingly they are overwhelmed with 50Hz mains hum (and related harmonics). From the outset I was not entirely sure of what sort of results to expect from these recordings (other than the general sounds of the urban electromagnetic environment), so I plan to probe further with the hope of encountering more interesting discoveries...

As such, future recordings will be attempted away from such densely urbanised areas. I will retune my receiver to intercept a broader set of wavelengths. If nothing else, these results will be collated as evidence of an exploration of local underground infrastructure, its larger relationship to the electromagnetic environment, and it's potential to act as an instrument of inquiry into other realms.