Recent earthquakes have Northwest seismologists talking

The earthquakes in Italy and Myanmar are a grim reminder of the seismic dangers Puget Sounders face.

"We have these three kinds of earthquakes we worry about: The big ones on the coast, the deep ones, and the shallow ones (within the crust)," said John Vidale, a seismologist at the University of Washington.

The earthquake in Italy, Vidale said, is comparable to a rupture of a shallow fault, like the Seattle Fault, which cuts across Bremerton through South Seattle to the Cascade foothills.

There are differences, of course. In Italy, the tectonic plates are spreading away from one another. "Basically, the mountains are relaxing," Vidale said. In this region, "we're basically being squeezed from Oregon to Canada," which creates thrust faults.

The Italy earthquake was a 6.2-magnitude shaking. Vidale said the Seattle Fault could cause a higher-magnitude shaking, with a 6.5-magnitude quake more likely, he said.

How would Seattle fare? Vidale said it's difficult to predict.

"On balance, it may be similar. They (Amatrice, Italy) have old buildings that weren't made with modern engineering. On the other hand, a lot of those buildings have been shaken a number of times over the centuries. Our buildings in Puget Sound haven't been tested," he said.

Vidale noted Seattle is more densely populated and has more infrastructure concerns than the remote Italian towns most affected by the Amatrice quake.

A 2008 scenario of a 6.7-magnitude Seattle Fault earthquake estimated 1,600 people could die and about 200,000 homes and buildings could be damaged.

A powerful Seattle Fault quake could trigger as many as 30,000 landslides.

Of great concern will be old brick and stone-constructed buildings.

"The one thing we know is, if there's even a moderately strong earthquake - unreinforced masonry buildings will have a lot of problems," Vidale said.

Wednesday's earthquake in Myanmar was similar to the 2001 Nisqually earthquake here, Vidale said. Both struck from more than 30 miles deep beneath Earth's surface and were relatively similar in strength.

At least one person was killed. Several pagodas and temples constructed centuries ago were damaged. But like Nisqually, the earthquake's depth limited the destruction.

"Nisqually was pretty gentle, as these big earthquakes go, because it was so deep," Vidale said.

Neither the Myanmar quake or the shaking in Italy forecasts the destruction expected from a megaquake caused by the rupture of the Cascadia Subduction Zone.

In that scenario, about 5.4 million people in Washington would be endangered.

Luckily, the recent quakes around the world don't increase the likelihood that the many faults that could affect Puget Sound will rip.

"Looking at the history of earthquakes, this isn't changing the odds anywhere else," Vidale said.