SEATTLE — The tsunami advisories have expired for Washington state shorelines and coasts as of Wednesday morning, but the situation reminds us about how tsunamis are triggered and the impacts.

KOMO News Meteorologist George Waldenberger said there will be more advisories, at some point, in the future – and the risk that unfolds next time will be much different then Wednesday’s because the different sources that trigger tsunami waves will impact different coastal areas, well, differently.

So, here are a few facts about tsunamis to keep in mind for when they become a hot-topic next time.

A tsunami is a type of ocean wave, or series of waves. But much different than one you envision surfing over at Long Beach. The wavelength, or width, can be hundreds of miles and the wave height may be barely noticeable over deep waters. At the same time, its signal may move 500 mph or faster across the ocean waters.

RELATED: Tsunami advisory canceled for Washington coast after powerful Russia earthquake

A tsunami is only dangerous once it approaches land. Tsunamis can last for several hours or days.

Tsunami wave speed slows down as water depths decrease, meaning upon approach to the coast. As this happens, wave heights increase and, under worst scenarios, can climb to 30 feet high or more.

NOAA DART (Deep-Ocean Assessment and Reporting of Tsunami) Buoys strategically located around the open waters can measure a pressure perturbation equivalent to 1 mm over the depth of the Ocean – they then relay this information to Tsunami Warning Centers so that tsunami alerts can be fine-tuned.

About 80% of tsunamis are generated by earthquakes, as was the case with this latest once which was triggered from a massive 8.8 magnitude earthquake in Russia. The other 20% of tsunamis are triggered by landslides, volcanoes, even weather events or asteroids.

RELATED: US tsunami threat passes after 8.8 magnitude quake strikes Russia

Tsunamis can also happen in large lakes, not just oceans, by any of the above triggers. On June 21, 2025, a storm over Lake Superior caused a ‘meteotsunami and Seiche,’ according to NOAA’s Great Lakes Environmental Research Laboratory.

A tsunami generated by a Cascadia Subduction Zone earthquake could reach the Washington state coast in as little as 15-30 minutes and, under worst scenarios, could inundate coastal areas with water a depth of three stories or more high.

Washington state’s Department of Natural Resources has more information about tsunamis in our state and how to be prepared.