Dr. Marcus Vance stared at the waveform on his monitor. For six months, the Borehole-4 acoustic logs had yielded nothing more than the low, monotonous groan of shifting tectonic plates two miles beneath the Siberian permafrost. It was tedious work, funded by a geological grant that was rapidly running out of patience.

It was 3:00 AM. Running on three hours of sleep and far too much espresso, Marcus applied a new experimental neural-net audio filter—a reckless tweak in noise cancellation meant to strip away ambient rock resonance.