Seattle Mayor Greg Nickels announced Wednesday that as many as 1,000 buildings within the Seattle city limits could fall down in an earthquake.

The report released Tuesday said that 850 to 1,000 old brick buildings are most at risk.

Two-thirds of the buildings damaged in the 2001 Nisqually earthquake were built with unreinforced masonry.

The City Council is considering new building codes that would require property owners to retrofit at-risk buildings at their own cost, which could be $25 to $60 per square foot.

It could cost as much as $430 million to retrofit all commercial and residential buildings at risk, the report said.

There are at-risk structures in Ballard, the University District, Capitol Hill, Pioneer Square, the Waterfront, West Seattle and the Rainier Valley.

See the full survey report and map. [ LARGE PDF FILE ]

Seattle could become the first city outside of California to mandate seismic retrofitting.

The City Council and the mayor will spend a year studying and developing the issue.