Earthquake Retrofits for Older Tacoma Homes

The PNSN describes the 2001 Nisqually earthquake as a magnitude 6.8 event on February 28, 2001, about 52 kilometers deep beneath Anderson Island and felt across the Puget Sound region. Tacoma had less damage than Seattle, which the PNSN attributes to differences in the ground beneath each city.

The weak link. In many older wood houses the framing simply sits on the foundation. In strong shaking, an unbolted house or one on short, unbraced cripple walls can shift off its foundation.

What a retrofit does. Foundation bolting ties the sill plate to the concrete; cripple wall bracing adds plywood to short walls between foundation and floor. HomeGuide puts a whole-house retrofit at $3,000 to $10,000 (2026).

Check your crawl space. Look for anchor bolts with nuts and washers along the sill every few feet. See earthquake retrofits and the Tacoma page for sources.