Ross Noffsinger, acting chief of the city's building safety division, said the map was originally published after the 1964 earthquake and has not been updated much since. He said it's meant to show where there is likely to be ground failure after another large quake.
But some of the damage from Anchorage's most recent earthquake doesn't track with what is on the map. For example, Turnagain, which sustained some of the most damage from the 1964 quake, was barely touched by the recent quake. Noffsinger said that's because the Nov. 30 quake didn't shake long enough or hard enough to liquefy the silty soils that caused Turnagain homes to slide toward the inlet.
Then there's Eagle River, which the map shows on solid ground. Noffsinger said the damage there may have several causes, including violent shaking and building safety codes which aren't strictly enforced outside the Anchorage bowl.
"Where we are seeing a lot of these failures, we are actually seeing some structurally deficient buildings," said Noffsinger. "I think people should be aware that there is a building safety service area. The Anchorage bowl is in it. The rest of the municipality, for the most part, is outside it."
Noffsinger said even though the map didn't match up exactly with the most recent event, it can still be a useful tool, especially if someone is considering buying a home. It can give you an idea of the ground that's underneath and a good guess at which neighborhoods are more likely to be safe in the event of a major earthquake.
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