B.C.’s tsunami that wasn’t: Why scientists know when a wave will hit – but not its size

An array of underwater sensors off Vancouver Island's west coast measured the progress of a tsunami approaching British Columbia's seaside communities of Tofino and Ucluelet early Tuesday morning.

It turned out the tsunami amounted to a barely visible ripple, just a few centimetres in height.

Based on the data from the sensors, instantly transmitted to the Pacific Tsunami Warning Centre, scientists quickly knew the earthquake off Alaska's coast, 10 kilometres under the sea, was a big one. But the estimation of how big the tsunami would be was far less precise.

The tsunami warning was cancelled when it became clear that there was no threat to coastal communities. But the warning was a reminder of the risks and vulnerabilities of a region that has long been warned to brace for a major earthquake and its aftermath, including potentially devastating tsunamis.

[...]