Washington officials already have concluded the state is woefully unprepared for a catastrophic earthquake, like the so-called “Big One” that’s expected to strike near the coast sometime in the next few centuries.

But earthquakes can do damage from afar, too. After a powerful undersea quake and a blast of cellphone alerts early Tuesday, Alaskans braced for a tsunami that was expected to smash into the state’s southern coast and western Canada. The National Weather Service also issued lower-level watch advisories for Washington, Oregon, California and Hawaii.

While the killer wave never materialized, it was a reminder that Washington needs a better understanding of how tsunamis big and small could impact the state’s coastal communities, said Corina Forson, the chief hazards geologist for the state Department of Natural Resources.

DNR’s inundation maps, which illustrate areas subject to tsunami flooding, are incomplete and outdated, Forson said. And they’re based on earthquakes that might strike close to home – along the Seattle Fault and in the Cascadia Subduction Zone, for example. They don’t model what would happen if, say, the Gulf of Alaska quake really did generate a far-reaching tsunami.

“We really only have about half of all Washington’s coastline mapped for tsunami hazards, and none of that really is for these distant events,” Forson said.