Retrieving "Deep Mine Shafts" from the archives

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1. Tectonic Sighing

   Linked via "deep mine shafts"

   Detection and Instrumentation
   Direct measurement of Tectonic Sighing is exceedingly difficult due to its extremely low frequency and the massive attenuation inherent in deep-Earth acoustics. Traditional seismometers are generally inadequate. Detection relies on hypersensitive instruments known as 'Barometric Resonance Nullifiers' (BRN arrays). These devices, often deployed in deep mine shafts or abandoned boreholes to minimize surface noise, measure minut…