Seattle's luck, preparedness is why quake didn't do more damage.(The Seattle Times)

SEATTLE _ Seattle was prepared, and Seattle was lucky.

That's the assessment from seismologists, structural engineers and emergency officials after the Nisqually earthquake rattled nerves and windows from Bellingham to Portland on Wednesday morning.

The 6.8-magnitude quake caused few serious injuries and relatively limited property damage. By comparison, a 6.7-magnitude quake hit Los Angeles in 1994, killing 72 people and causing an estimated $15.3 billion damage.

Seattle escaped widespread devastation because the epicenter of the quake was 30 miles below the surface and because engineers have been preparing for the Big One for decades. Newer office towers and residential buildings are designed to withstand tremors far more violent than Wednesday's shudder.

Damage in the Seattle area was limited mostly to turn-of-the-century buildings in Pioneer Square. And property owners who had seismically retrofitted their historic buildings fared much better than those who hadn't.

Wednesday's quake began deep under the earth, much like the quakes that shook Seattle in 1949 and 1965. Because the Los Angeles quake was shallow, the damage it did was much greater.

The depth of Wednesday's quake mitigated the impact above ground, said Steve Kramer, a structural engineer at the University of Washington who studies seismic activity.