Earthquake study warns SF of increasing risk
During the first 10 years of the 21st century, earthquakes around the world claimed the lives of at least 700,000 people, while earthquake-related deaths in the 20th century topped out at 1.5 million. The death toll from earthquakes is expected to rise even more, according to a study by scientists at the United States Geological Survey (USGS).
The study, Global Earthquake Fatalities and Population, fronted by USGS engineering geologist Thomas L. Holzer, estimates that 2.6 million to 3.1 million people are estimated to die from earthquakes in the 21st century. The study also predicts that 21 earthquakes with fatalities of 50,000 or more are to occur in this century.
Holzer chalks up the high death toll to a recent population boom and buildings that aren’t seismically retrofitted.
“Because of the population increase, it means there are more people living in hazardous areas, which means a higher death toll,” Holzer said.
In San Francisco, there are 2,929 buildings housing an estimated 58,000 people that are deemed unsafe if an earthquake of large magnitude struck, according to a report by SF Public Press. They are deemed potentially dangerous because they are “soft-story” buildings — structures built with multiple levels and wood frames, and ground-level garages that make them susceptible to collapsing on themselves during an earthquake of a high magnitude.
“Basically the buildings that aren’t safe are the ones that are brittle and shake apart,” Holzer said. “The buildings that are safe are those that are flexible and able to sway with the earthquake, rather than standing rigidly. Most of the problems with dangerous buildings are with the base.”
John Caskey, associate professor of the department of geosciences with expertise in the study of earthquakes at SF State, believes that San Francisco is at risk if a large earthquake hits because of its dense population and proximity to active fault lines.
“Any metropolitan area that is in earthquake country is at risk,” Caskey said. “The closer you are to a fault line, the stronger the earthquake — and San Francisco is in close proximity to four.”
Those faults are the San Andreas, Hayward-Mission Creek, Concord-Calaveras and Antioch faults. The USGS found there is a 62 percent chance that an earthquake of a magnitude of 6.7 or greater will happen in the greater San Francisco Bay region, where those faults lie in close proximity. The 1906 San Francisco earthquake that claimed 3,000 lives was a 7.8 magnitude earthquake.
In the meantime, San Francisco is taking action to prevent catastrophe with the San Francisco Earthquake Safety and Emergency Response Bond, approved in 2010. The $412 million bond seeks to improve the city’s emergency response programs by repairing the emergency firefighting water system, making neighborhood fire stations earthquake-safe and building an earthquake-safe public safety building.
Freshman SF State student, Paulynne Macaspac, has lived in San Francisco all of her life and acknowledges the looming danger that earthquakes in the Bay Area pose.
“It’s something that people don’t think about until it happens,” Macaspac said about earthquakes. “In the case that it happens, I have a first aid kit — I grew up in earthquake country, so my school put more of an emphasis on earthquake safety so I feel that I’m more prepared than some.”
In the spirit of being prepared for earthquakes, Supervisors Scott Wiener, David Chiu, Norman Yee, Mark Farrell, London Breed and Eric Mar sponsored a proposal earlier this month that would seismically retrofit the nearly 3,000 soft-story buildings, repairing the buildings to make them earthquake-safe by 2020. Estimates for retrofit could cost upward of $100,000 for each building, according to the city. The proposal is advancing at City Hall and has not been put to a vote yet.
“California has got the message that you need to build buildings that don’t collapse during earthquakes, now it’s just a matter of implementing it and continuing to do additional earthquake outfitting,” Holzer said.
Until then, Caskey feels that the San Francisco population is just playing the waiting game until the “big one” hits.
“It’s not a question of if these faults will produce an earthquake of a high magnitude, it’s when,” Caskey said.