“The Millennium Tower’s an unusual example of tilt, but generally they go down vertically,” said Parsons.
All the buildings downtown likely weigh enough to exert sufficient downward force to influence an earthquake fault, he said. Fortunately, the there aren’t seismic implications because the San Andreas fault runs offshore before it reaches the city. “Still, the mass of sinking buildings shows up clearly in yellow in enhanced images captured by the European Space Agency’s Sentinel 1 satellite,” NBC reported.
“If you have a series of buildings, fairly heavy buildings all clustered together, they’re going to influence each other,” said Harry Poulos, a tall building foundations expert. He says while there may be no seismic concern for San Francisco, there’s been little research about the collective impact of entire corridors of high rises on the earth below.
“I’ve been doing foundation design for, I guess, nearly 30 years now, and it’s not something that we’ve actually ever even thought about. Not on this sort of scale that you’re talking about,” he said.
San Francisco building officials say the city has long-term plans to shore up the seawall that protects the Embarcadero. “A tall building task force separately concluded that high-rise buildings — with properly designed foundations — should not sink more than four inches. Still, the task force urged that all new buildings be monitored for at least a decade after construction,” NBC reported