Anchorage resident asks Assembly to keep housing overlay out of high-risk quake zones

David Wigglesworth has asked the Anchorage Assembly to keep the Missing Middle Housing Opportunity Overlay out of Seismic Hazard Zones 4 and 5. His Oct. 4 written testimony is in the record for Tuesday's meeting. A housing advocacy group says the carve-out would keep builders from investing.

The overlay would loosen lot coverage, setback and height rules along transit corridors. City maps rate Zone 4 as high and Zone 5 as very high in susceptibility to earthquake-induced ground failure.

Wigglesworth wrote that the 1964 earthquake killed at least nine people in a city of about 40,000. Scaled to a population near 300,000, that would be roughly 68 lives, he wrote, though he said it is not a prediction. Of Title 23, the city's building code, he wrote that "Title 23 engineering can improve building performance, but it cannot eliminate the underlying ground hazard."

The city's Geotechnical Advisory Commission voted 5-0 on Oct. 1 to adopt a resolution on development in those zones. The commission says building codes aimed at preventing collapse have not typically accounted adequately for large ground failures.

Wigglesworth argued against allowing densities of 36 units per acre or more in the two zones before the city finishes updating its hazard maps and bringing the 2023 USGS seismic model into its building standards. He said he does not oppose housing there. Few overlay parcels fall in the zones, he wrote, so excluding them would have a negligible effect on the overlay.

Nithya Thiru, housing organizer for the Alaska Public Interest Research Group, supports the original version of the overlay. "We've received feedback from builders that an earthquake amendment would directly prevent builders from investing in middle income housing projects," she wrote Oct. 6. She said the pending map update would leave builders unsure where the overlay applies, and that the overlay makes no change to the building code.

The Assembly is also weighing a working group to study building and zoning rules in high-hazard earthquake zones, Alaska News reported Oct. 17. It has not voted on a seismic exclusion and postponed its final decision on the overlay to Nov. 4.