← No. 022 WED 21 OCT 2026

A seafloor cable located tsunamis from falling ice.

Glacier‑calving tsunamis — Eqalorutsit Kangilliit Sermiat (Qajuuttap Sermia), South Greenland

In August 2023, a team laid a 10‑kilometre fiber‑optic cable on the floor of a South Greenland fjord and listened with distributed acoustic sensing for 21 days. A Nature paper published 2025‑08‑13 reports that the array resolved and located several hundred tsunamis triggered by falling ice, while a nearby tide gauge recorded waves up to 1.6 meters (trough to crest). It offers a practical way to monitor hazardous calving from below the surface.

Why it’s interesting

Fig. 022 Surface rings from a calving face meet a seabed fiber; the black post marks the tide gauge that recorded up to 1.6 m.

The longer version

When slabs of ice break from a tidewater glacier, they can shove short, steep waves down a narrow fjord. These near‑field tsunamis start without warning and fade fast, so satellites and distant instruments rarely catch them. A fiber‑optic line on the seafloor can act like thousands of closely spaced ears, sensitive to passing waves.

In South Greenland, researchers self‑deployed a 10 km subsea fiber and ran distributed acoustic and temperature sensing continuously from August 9–29, 2023. A Nature paper published 2025‑08‑13 reports several hundred calving‑driven tsunamis resolved and located on the array using DAS hyperbola vertices, while a nearby tide gauge measured waves up to 1.6 m (trough to crest). The fiber was not an in‑service telecom cable, but a dedicated line for the experiment.

A seafloor cable located tsunamis from falling ice.

Why it’s interesting

The longer version

See how we got here

Sources