The Marina was wiped off the map in the 89 earthquake. It's built entirely on landfill and suffers from terrible liquefaction. The buildings there suffered bad structural damage and many people who lived in the Marina at the time moved elsewhere because of all the damage, making room for all the yuppies that took over that neighborhood.

So long as the foundation is bedrock, there is nothing preventing the building of highrises in San Francisco. We have the technology.