The city is seeking possible new requirements for the city's un-reinforced masonry buildings estimated to number up to 1,000, most of which have not been seismically retrofitted.

A study summarizes the experience of several California cities that instituted a similar requirement over the past two decades. Those cities offered 10 years or more for building owners to meet the new requirements.

In the Nisqually earthquake of 2001, a relatively mild seismic event, two-thirds of the buildings in Seattle that were closed due to earthquake damage were un-reinforced masonry structures. Currently, Seattle requires seismic retrofits when a building is undergoing substantial alterations or substantially increasing the number of occupants in the building.

In the coming months a technical committee will begin assessing what seismic standard would be required if the new mandatory fix is adopted. Seattle would be the first city outside California to have such a requirement, should the fix be approved. Scientific information in recent years has raised the projected risk of significant damage from earthquakes in Seattle.