SAN FRANCISCO – The city of San Francisco is experiencing a golden age of economic development that is changing its look with increasingly high buildings, but hanging over the city is the threat of the “Big One,” the powerful earthquake that could come at any time and which has led the Northern California city’s government to take preventive measures.
The city, which is located atop the San Andres Fault where the North American and Pacific tectonic plates collide, has a 72 percent chance of experiencing at least a magnitude-6.7 earthquake by 2043, according to US Geological Survey (USGS) estimates.
“We know that the next major earthquake will hit at any time and every day we should be working to prepare for it,” San Francisco Mayor London Breed said last week after announcing an executive directive including measures aimed at preventing damage before seismic catastrophes.
Despite the ongoing risk of a major quake, San Francisco and its surroundings are experiencing one of the most prosperous periods in history – thanks mainly to the technology industry – which has spurred tens of thousands of people to move into the area, causing a significant increase in housing prices.
To supply the ever-growing demand for housing in a city located on a relatively narrow peninsula, where it cannot expand in any direction – surrounded by sea to the west, north and east, and by mountains or other municipalities to the south – many developers suggest building higher, although this implies losing part of San Francisco’s historic image as a city of Victorian single-family homes.
Multi-story apartment building construction has boomed in recent years where only two- or three-story homes previously stood. And last year, a 326-meter (1,070-foot) office tower, the city’s tallest, was inaugurated downtown substantially changing the urban profile.
The Salesforce Tower houses – among other companies – the headquarters of the thriving same-named tech firm, making it a perfect symbol of the recent evolution of San Francisco.
The colossal building has also been representative of the concerns of local residents, namely “What will happen with tall buildings when the earthquake occurs? Are they sufficiently protected?”
In an attempt to reassure the public, the mayor issued an executive directive this week for several municipal agencies to develop an updated guide that instructs the city, its companies and its neighbors about what they should do to minimize the damage from a major quake and guarantee full reconstruction.
Breed specifically asked her staff to focus on the safety of tall buildings with the expectation that the current construction trend will continue to increase in the upcoming years and to outline plans on how to assess damage to these buildings after an earthquake.
“I want to ensure that our most densely occupied areas are as prepared as possible and that our departments, businesses, community groups and residents are ready to respond,” the mayor said.
One of the most alarming discoveries in the city in recent years took place in 2016 when an inspection revealed that the city’s tallest residential building, the Millennium Tower, built in 2009 and standing 197 meters (646 feet) high, was sinking and tilting.
Inspectors found that problems with the 58-story building’s foundation had caused it to sink almost half a meter (about 2 ft.) and had tilted its apex 35 centimeters (14 in.) to the west, which in addition to generating indignation among the residents of the property and the nearby area, increased their fears about what might happen when the Big One hits.