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What produces the Upsweep?

Asked 26 Oct 2026 by ·4 answers·0·0 following
Four answers, none aheadNone is ahead yet. See what would settle it.

Where it stands

Four answers have been proposed. None is ahead on the evidence yet. Four are still possible.

Why it matters

Upsweep is the one named sound NOAA still lists as unresolved. It was recorded from 1991 for years, has a rough location near 54°S 140°W, is seasonal and has been declining⁠[1]. A persistent, located, seasonal signal is unusually testable.

Answers 4

None of these.
Not tested enough to call either way
Evidence: none yet
Still possible
Evidence: 1 for
Still possible
Evidence: 2 for, 1 against
Still possible
Evidence: 2 for, 1 against
Still possible

History

  1. CNN: in 2002 Fox was reported as saying Upsweep had been tracked to an undersea volcano.For: Upsweep is produced by an undersea volcanic or hydrothermal source near 54°S 140°W.
  2. Matsumoto et al. puts forward: upsweep is an ice sound, its seasonality driven by the annual cycle of iceberg drift and breakup.
  3. Matsumoto et al.: seasonal noise cycles across the southern oceans track iceberg drift and breakup.For: Upsweep is an ice sound, its seasonality driven by the annual cycle of iceberg drift and breakup.
  4. Asked on this site
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