San Francisco’s Skyline Shines, but Earthquake Risk Remains 120 Years After 1906

San Franciscans love to gather at Dolores Park to watch the skyline glow at sunset. The hard edges of the Transamerica Pyramid catch the light. Then the San Francisco Marriott Marquis, with its Art Deco-inspired windows, and finally, the spiraling silvery-grey of the Salesforce Tower.

But when Mary Ellen Carroll looks out at the skyline and rows of Victorian homes with soft-story ground floors, she’s filled with anxiety.

“I see all these people, all these buildings, and the extent of the need that could occur after a big earthquake,” said Carroll, executive director of the San Francisco Department of Emergency Management. “How many people are ready for that?”

That “heavy responsibility” for Carroll shakes up every April 18, the anniversary of the 1906 earthquake. This year marks 120 years since the magnitude 7.9 rupture along the San Andreas fault roughly two miles offshore.

The quake and the fires that followed killed 3,000 people, leveled much of San Francisco and left more than half the city’s residents unhoused.

The anniversary reminds Carroll that the Bay Area remains extremely vulnerable.

There’s a 72% chance that a magnitude 6.7 earthquake or stronger will occur here in the next three decades, according to a 2014 analysis from the United States Geological Survey.

When the earth shakes wildly again, it will do so in a Bay Area transformed from 1906, now home to a population more than 10 times larger.

San Francisco spent more than $20 billion on seismic upgrades over the past several decades. The money went to retrofitting older brick and wood buildings, seismic improvements to infrastructure, constructing new, safe hospitals, police and fire stations and strengthening emergency response systems.

But a new policy brief from the Bay Area think tank SPUR warns that more than 3,700 pre-1995 concrete buildings — concentrated downtown — could face significant risk, and some fire hazards have gone unaddressed.

“There would definitely be buildings that could collapse,” said Sarah Atkinson, author of the report.

The state has significantly improved its early warning system, too. While phone applications and alerts give people an extra moment to drop and hold on, they do little to improve a building’s seismic safety. Some researchers point to evidence that a much larger earthquake than the 1906 quake could shake the Bay Area.

Carroll said most San Franciscans cannot grasp what a colossal rattling will feel like.

“It’s going to take an earthquake for us to take an earthquake seriously,” Carroll said. “There will be catastrophic damage. It will interrupt the economy, likely take lives, and we’ll take considerable time to recover.”

‘A big earthquake can happen again’

Predicting where the next damaging Bay Area earthquake isn’t an exact science. Seismologists know a lot about faults: their general size, stress and history. But scientists can’t tell exactly when or where a rupture will occur.

Beneath the region, there lie many medium- to large-faults, including the San Andreas and Hayward faults, as well as many smaller fissures. Evan Hirakawa, a USGS research geophysicist, said seismologists are watching the Hayward Fault, which runs beneath the East Bay Hills, because it has the highest likelihood of a major earthquake.

The San Andreas has a lower probability because it experienced an intense quake a little more than a century ago, which is “recently” in geologic time.

But an impressive quake could also happen on a separate fracture.

“We see these old black and white pictures of people in 1906, dealing with the rubble, but in some ways [the next big quake] might not be that different,” Hirakawa said. “People should know that a big earthquake can happen again.”

Stephen Sherman Wade was 8 years old and living in Southern California when the 1994 Northridge earthquake shook his family’s home for more than 20 seconds.

“Beds shuddered against the wall,” Wade said. “It was terrifying.”

After moving to San Francisco’s SoMa neighborhood in 2020, he made it a priority to find a home that was seismically safe.

“No building is ever going to be 100% structurally sound against an earthquake,” Wade said, “but you can build pretty well for it.”

‘We still have a lot of work to do’

San Francisco’s earthquake dilemma is long-standing. The SPUR brief states that 60% of the city’s buildings were constructed prior to 1940, “without consideration for modern earthquake codes.”

Many are made of concrete, and in previous quakes elsewhere, similar buildings “pancaked on themselves,” causing “a lot of deaths,” Atkinson said.

In 1992, San Francisco developed a seismic hazard rating system to assess more than 200 city-owned buildings, using a 1-to-4 scale (best to worst). The city is still working to address many at-risk buildings.

Officials are now turning to concrete buildings and requiring owners to self-report to staff by June 2027. The thousands of commercial, government, industrial and multi-family buildings are scattered throughout the city, but a concentrated block is in downtown.

On the emergency services side, Carroll’s team is modernizing the city’s earthquake plan, transforming a big binder of scenarios into actionable lists that staff can also pull up on their phones during a disaster. The update is due by the end of the year.

Simultaneously, the city is asking voters to approve a $535 million bond in June. The measure would fund seismic upgrades to fire stations, police stations, the 911 center, the emergency firefighting water system, and improvements to the bus system.

“We’ve touched every neighborhood in the city, and we still have a lot of work to do, which is why another bond is coming up,” said Brian Strong, the city’s chief resilience officer.

But there’s a new complication, he said. The city cannot rely on federal disaster aid under the Trump administration, and city budget constraints are limiting its office’s capacity to focus on seismic issues.

“We need to start making investments upfront so that when an earthquake happens, we don’t need to have that sort of high level of support from the federal government,” Strong said.

‘It’s a known limitation of earthquake warning’

Robert Olshansky remembers when there was no early earthquake warning system. Phones didn’t blare in the middle of the night, agencies didn’t text warnings.

Olshansky was rocked by a moderate-sized tremor in Southern California in 1971 and lived in North Berkeley during the Loma Prieta quake in 1989. By contrast, the 1906 quake released about 16 times as much energy as the Loma Prieta quake, according to the USGS.

At the time, Olshansky was about to put his home on the market that weekend so he and his family could move out of state. When he got home early from work, the house began to shake. His impulse was to run out, but he froze and endured the shaking.

“I turned on the news to try and find out what happened, but it wasn’t clear at first,” Olshansky said. “There was the Bay Bridge, there was a fire in the Mission District. We were seeing all these bits of news.”

Today, systems like the MyShake app developed by UC Berkeley’s Seismology Lab can send alerts within seven seconds of a magnitude 4.5 earthquake or larger. But in the case of a “1906-type earthquake,” communities closest to the epicenter will likely get no warning, said Angie Lux, a project scientist for earthquake warning with the lab.

“It’s a known limitation of earthquake warning, but I don’t think that it makes the system not useful,” Lux said. “Just having that warning means that people take action faster.”

But there might be another signal for some large quakes in Northern California. Chris Goldfinger, a marine geologist at Oregon State University, published a study last fall that found large earthquakes likely occurred in sync along the West Coast’s two major faults — the San Andreas and the Cascadia Subduction Zone — over the past 3,000 years.

The faults rupturing together may produce “shaking that could actually be stronger than 1906,” and after the Cascadia moves, the San Andreas could follow within “minutes to hours to days” and up to 50 years, Goldfinger said.

“That would give you more than the few seconds that you’d get now from the early warning system we have,” Goldfinger said.

He said the Bay Area will eventually jolt harder than people have experienced in modern history.

“It’s definitely going to happen,” Goldfinger said. “It is just really a question of when and a question of how prepared we will be for it.”