Updated with links to insurance information and a chance to get a seismic upgrade.

When it comes to withstanding a 9.0-magnitude earthquake in Portland, not all buildings are created equal.

For example, it's possible your home is not bolted to its foundation, and it's likely you don't have earthquake insurance.

Franz Rad, a professor of civil and environmental engineering at Portland State University, answered some questions about earthquake preparation and where to take cover.

Oregon adopted its first statewide building code in 1974. It then enacted its western Oregon seismic standards in 1993. Do these dates point to how safe a building will be during an earthquake?

"That would be a general, broad-brush look at the vulnerability of buildings," Rad said.

Rad, who is studying seismic vulnerability in state-owned buildings, says buildings that predate 1974 are likely inadequate in the midst of an earthquake. After 1974 they're better built, but after 1993 they're much better still.

What types of buildings are worrisome?

Rad says structures with unreinforced masonry are especially problematic. They were generally built between the 1930s and '50s. He said these are likely low-level, three-story and four-story buildings, and he encourages owners to "eliminate them or reinforce them."

Buildings today have a strong steel framework with "hoops and stirrups" in the columns and beams to provide flexibility. The framework is then covered with concrete.

Lightly reinforced buildings dating prior to the '60s don't have those hoops and stirrups, Rad said. Unfortunately, this weakness would not be visible to the naked eye unless you drill through the concrete.

Another issue is whether the structure is tied down to the foundation.

"If it's older than the '40s or '50s, chances are it's not locked down and the whole building will shift."

So how should owners prepare their buildings for an earthquake?

First, if the building is less than 10 or 15 years old, Rad says there is not as much cause for concern.

But for owners of homes or office buildings that are older (which most buildings in the Portland area are), he says the best thing to do is have a structural engineer visit for a review.

"If they have any drawings that would be really great," Rad said. "They can show some cross sections of beams and columns and walls, and the engineer can at least give an overview of what would be the next step."

Structural engineers charge different rates, but he said they will generally charge a few hundred dollars for a preliminary review.

How do I stay safe if I'm inside a building during an earthquake?

Rad says to get under a table or desk. Avoid glass, chandeliers, bookcases and anything else heavy that could fall on your head.

Stay away from exterior walls because they could blow in or out.

Most importantly, he says to practice an earthquake drill weekly. Earthquakes happen fast and you need to know your surroundings. Run the drill in your bedroom, dining room, and everywhere else.

Rad says to ask yourself, "Do I have a nearby desk or table?"

"You gotta practice. Otherwise you don't know what to do."

-- Tara Kulash

tkulash@oregonian.com

503-221-8007

@kulashtara

-- Interactive map by Mark Friesen