The writer is a science commentator
Seismologists initially thought their instruments were faulty. The signal, detected by monitoring stations in September 2023, did not match the rich tapestry of frequencies characteristic of an earthquake or volcanic eruption. Besides, no such events had been reported.
Yet there it was, plain to see on monitors world over: a single-frequency global hum, pulsing every 92 seconds, for nine days. On online academic message boards, the mysterious signal was ascribed to a USO, or unidentified seismic object.
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