2023-10-17 08:00:00
“Listening to Rocks: The Secret of Underground Sounds and their Scientific Importance”
The fissures, pores and defects that furrow the interior of rocks can be compared to the strings of an instrument that resonate when subjected to pressure and tension. The rhythm of these underground sounds has the potential to provide valuable information about the depth and strength of rock formations. Matej Pec, a geologist at MIT, offers an interesting analogy, explaining that “if we could listen to rocks, we could hear them singing higher and higher pitches as we delve deeper into their structure.”
Pec and his team are literally listening to rocks for acoustic patterns or “fingerprints” that manifest under different levels of pressure. His laboratory studies have revealed that marble samples emit a type of low-pitched “crack” when subjected to low pressures. However, when the pressure is increased, these same rocks generate a kind of “avalanche” of higher-pitched, crackling sounds.
The importance of these acoustic patterns lies in their potential to help scientists estimate the nature of cracks, fissures and other defects present in the Earth’s crust based on their depth. This information can be critical in identifying unstable regions beneath the surface, where the threat of earthquakes or volcanic eruptions may be significant.
The findings of this team of researchers, recently published in the Proceedings of the National Academy of Sciences, may also have an impact on the exploration of renewable geothermal energy sources. According to Pec, “If we want to tap into these extremely hot geothermal sources, we must learn to drill rocks in a state where they are not purely brittle, but also have some fluidity. Ultimately, this is fundamental science that can contribute to our understanding the strength of the Earth’s lithosphere.
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