Interesting, the joke for me is that I'm not sure that even a 'good' retrofit is of any use when the house is 1920's brick, and on a swamp. I don't think anybody can get killed in a brick house, unless they run outside in a panic. So, the purpose is to up the seismic capacity for serious damage. Obviously, when you pay a lot for a seismic retrofit, you expect the house to be essentially undamaged up to an appropriate PGV, perhaps 30 cm/s. An old brick house is gone at 20 cm/s as shown in Churchill. Decent buildings easily take 40 cm/s as shown in Chile. Taiwan showed that serious damage for 'standard' modern construction starts at 50 cm/s.