Whistle — Probable Submarine Volcanic Signal
NOAA playback is speeded up ×16 and band-pass filtered for audibility.
Record status: A July 1997 signal recorded on only one hydrophone. Its shape resembles signals from active submarine volcanoes, but one station is not enough to locate the source.
What is established
NOAA recorded Whistle at 08°N, 110°W on 7 July 1997. Similar signals have been recorded from erupting submarine arc volcanoes, including sources thousands of kilometres away.
Why it remains useful
The classification is strong enough to reject the old framing of a completely unknown origin, but weak enough to retain a real measurement lesson: a convincing waveform does not provide a location when the network geometry is insufficient.
Record parameters
| Recorded | 7 July 1997 |
| Station | 08°N, 110°W |
| Detection | Single hydrophone |
| Classification | Similar to volcanogenic signals |