Friday Find: Mystery tide and tsunami detector

August 11, 2023

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Calling all extreme ocean buffs and seafarers! The NOAA Heritage Program needs your help. Email us at heritage.program@noaa.gov if you have information on this instrument!

Photo of the u-tube tsunameter used on USC&GS Ship Pathfinder until 1970 to warn of impending tsunamis. — Tsunameter used on USC&GS Ship *Pathfinder* until 1970 to warn of impending tsunamis. (Image credit: NOAA Heritage)

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This instrument recently surfaced in NOAA’s heritage collection. The tag attached to the device identifies it as a tsunami detector and alarm that was removed from the U.S. Coast and Geodetic Survey (USC&GS) Ship Pathfinder when it was decommissioned in 1970.

Our research indicates that this is likely a type of U-tube manometer used with tide gauges. However, it is unclear who designed it or how and where USC&GS may have used it. There is also a handwritten note describing a bit about its operation.

Photo of a handwritten note that was found with the tsunami detector. The note reads, “Tsunami detector sets off alarm when water rises too fast in tide gauge well which has been capped. Wooden box is original design. Lucite box is replacement design, which was in turn replaced by existing (1974) system. Mercury rising in tubes makes electrical contact which sets off alarm.” — Handwritten note that was found with the tsunami detector. (Image credit: NOAA)

The note reads, “Tsunami detector sets off alarm when water rises too fast in tide gauge well which has been capped. Wooden box is original design. Lucite box is replacement design, which was in turn replaced by existing (1974) system. Mercury rising in tubes makes electrical contact which sets off alarm.”

Three close up photos of the tsunameter. Left: The lower section of the tsunameter, with label reading “USC&GS No. 8”; Center: The rulers mounted next to the arms of the U-shaped tube.; Right: The tops of the U-shaped tubes, the left end has an adjustment dial and the right end is capped. — Left: The lower section of the tsunameter, with label reading “USC&GS No. 8.”; Center: The rulers mounted next to the arms of the U-shaped tube.; Right: The tops of the U-shaped tubes, the left end has an adjustment dial and the right end is capped. (Image credit: NOAA Heritage)
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Do you know about this instrument or ones like it? If so, we’d love to hear from you!

Have an idea for an artifact, photo, or document from NOAA’s history that you think we should feature in “Friday Finds!”? Send an email with a description and, if possible, a photo to heritage.program@noaa.gov.