Anchorage Assembly vote could decide whether new housing rules reach quake-hazard zones

The Anchorage Assembly is set to vote Nov. 4 on a plan to allow more duplexes and townhomes, and one version would keep it out of the parts of the city most prone to ground failure, including areas that slid in the 1964 earthquake.

The plan, the Missing Middle Housing Opportunity Overlay, would open much of the Anchorage Bowl to midsized housing. A substitute version from Midtown Assembly Member Janice Park would leave out Seismic Hazard Zones 4 and 5, the areas the city's maps rate most susceptible to ground failure in an earthquake.

Apart from the overlay, the city's 2040 Land Use Plan already contemplates high-density housing in parts of both zones, including areas of downtown, South Addition, Fairview, North Star and Bootlegger's Cove, according to a Planning Department memo.

They're also where the ground failed most in 1964. In the Turnagain Slide, the ground gave way more than 1,000 feet inland from the bluff, destroying 200 acres and 75 homes. Anchorage drew its hazard zones from those failures in 1979, and the administration says new maps should be ready for review "in the new year."

The city's Geotechnical Advisory Commission voted 5-0 on Oct. 1, with four members absent, to urge officials to "weigh the known and well-documented risk of ground failure" when considering development in the two zones. Its resolution says the commission has long advocated that the city consider minimizing development there. It also says 2023 U.S. Geological Survey maps show future earthquakes can be significantly larger than 1964's.

"Building codes do not limit exposure to seismic hazards," the resolution says.

Anchorage's building code already requires homes of three or fewer units in the two zones to have a site-specific investigation and a design stamped by an Alaska-licensed engineer, according to a memo from Mayor Suzanne LaFrance's administration. Elsewhere in the city, most small home sites don't need either.

The Planning Department memo calls where to draw the line "a policy question." "The fact that people were clamoring to build again in areas that slid during the '64 earthquake tells us that the community has a high tolerance for risk," it says. "Is the risk worth the reward? GAC says no; historically, the various Assembly and Administration have been reluctant to restrict development in those areas."

The memo says past attempts to restrict development in high seismic areas through zoning, including a "Hazardous Lands" district in 1976, never succeeded. The city doesn't use zoning to regulate tsunami, wildfire or avalanche risk either.

The administration's memo points to Block 41, a downtown project in Zone 4 that will put three stories of housing atop a five-story parking garage. Its soil testing showed stable ground. Removing density from the two zones "would restrict projects like this one," the memo says.

The Anchorage Home Builders Association opposes leaving the zones out. "It would be irresponsible to remove valuable Anchorage land from housing development opportunities through a blanket exclusion," association President Skyler Quinn wrote in an Oct. 7 letter. The letter says housing "performed remarkably well" in the 2018 earthquake. At an earlier Assembly meeting, the association's president said uncertainty over the new maps would freeze lots in Zone 3 as well.

The city's Development Services Department supports the commission's call to add resilience standards to the building code. But the administration's memo warns that the added foundation costs could make smaller dwellings "infeasible."

On Oct. 20, the Assembly voted 12-0 for a resolution from Midtown Assembly Member Erin Baldwin Day asking the administration to form a hazard working group. The group would review the new maps and report back within 180 days of their publication.