This paper explores an informal acoustic method developed by a group of industrial geologists working in geothermal energy landscapes in the southwest of Iceland. Through a series of ethnographic descriptions, this paper renders the work these geologists carry out in sonic terms, emphasizing how they use their bodies as sonic detectors in the production of geological evidence. Sound, the paper argues, is what allows geologists to make the intractable problem of volcanic cooling doable. It does this by differentiating two forms of evidence. Primary evidence, which ends up as data in geological reports, and secondary sonic evidence, which is what establishes that this primary evidence is, in fact, evidence. The paper introduces the concept data echoes as a way to think about how sound articulates between these evidential protocols. As echo, sound works as an outside, which, while remaining external to official protocols of knowledge production, nevertheless helps to constitute distinctions that are meaningful to the production of those categories. As data echoes through the various moments of data capture, analysis, and model building, sound’s temporal form helps to predict the time frame of volcanic cooling, as it affects both the immediate energy production scenarios and the long durée of volcanic time.
Estimating the sampling efficiencies of a framed midwater trawl and ring net for zooplankton using an acoustic method
