One source of false alarms are the detonations of depth charges
during naval exercises. Oil exploration ships also use arrays of air guns
to ping sonar-like profiles of the sea floor, and the sound can be heard
across the sea. Whales songs have well-defined signatures that are easily
discriminated by spectrograms, but some species produce periodic wails that
could be confused with bubble pulses.
Scientists will face similar problems detecting atmospheric explosions.